JP2975530B2 - Organic superlattice material, method for producing the same, and device using the material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic superlattice material used as a nonlinear optical material or an electronic material, a method for producing the same, and an electronic device and an optical device using the material.

[0002]

2. Description of the Related Art High-functionality electronic devices such as ultra-high-speed transistors, opto-electronic devices such as lasers, and optical control devices for modulating and switching light require new materials having the necessary material functions. . It is widely recognized that a superlattice material, which is a material that does not exist in nature, is effective as the new material, and material development is being carried out mainly on compound semiconductors.

[0003] The superlattice material is a material that develops new physical properties by stacking a plurality of thin films whose physical properties change for each layer. High-speed transistors and the like have been realized by using this material. For the principles of physical properties of these superlattice materials, basic design concepts, and necessary fabrication techniques, see “Physics and Applications of Semiconductor Superlattices”, pp. 1-129 (edited by The Physical Society of Japan, published by Baifukan (1984)). )It is described in.

[0004] The basis of the phenomenon that occurs when a material is made into a superlattice is that the energy level by confining the electronic state representing electrons or holes, which are usually spread three-dimensionally, in a quantum well, which is an artificially created potential, is considered. And the resonance effect that occurs between the quantum wells. Also,
As the fabrication technology, the film thickness is controlled by the thickness on the order of atoms and molecules, and a crystal structure without disorder and a sophisticated interface between dissimilar materials are required. Therefore, molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) are required. ) Is commonly used.

However, a superlattice material using an ordinary compound semiconductor is limited in its constituent material and its design is limited in terms of physical properties. Therefore, an organic superlattice using an organic compound as a raw material is a completely new material system. Lattice materials have been proposed. It is thought that the possibility of obtaining a new superlattice material is widened by using an organic compound as its constituent material. Research and development on this organic superlattice has only just begun, and very few examples have been realized.

FIG. 16 is a sectional view of a conventional example of an organic superlattice actually manufactured. This is manufactured by an organic molecular beam evaporation method using perylene derivatives and naphthalene derivatives, which are typical planar π-conjugated compounds, as raw materials. "Applied Physics Letters" No. 56
Vol. 7, p. 674 (published by the American Physical Society (1989)
Year)), 70 is a quartz substrate layer which is a substrate,
71 is a perylene derivative thin film layer, and 72 is a naphthalene derivative thin film layer. It is reported that the quantum effect is exhibited by the slight shift of the absorption spectrum in the material. Also, Ishitani et al. Have prepared and reported an organic superlattice material composed of hydrogenated tetraphenylporphyrin and zinc tetraphenylporphyrin, which are planar π-conjugated compounds. ("Journal of Applied Physics," Vol. 73, No. 6, page 2826 (19
1993)).

[0007]

The conventional organic superlattice material is constituted as described above, for example, and a shift in the absorption spectrum is observed. However, effects such as a significant improvement in the physical properties are observed. There was no problem. Originally, changes in physical properties expected to be realized by the realization of organic superlattices, such as improvement in electrical conductivity and increase in nonlinear optical constant, were not observed because the physical properties required for those superlattices were The material design is not optimal.

At present, an organic molecular beam deposition method is most commonly used as a method for producing an organic superlattice, but this production method is still in the research and development stage, and applicable materials are currently available. Limited. Therefore,
At present, the superlattice is made of a combination of materials capable of molecular beam deposition, and it is a multilayer thin film, but it is not an original superlattice material exhibiting novel physical properties. As described above, in the conventional organic superlattice material, no constituent material is selected based on the material design for producing the superlattice. That is, it is necessary to design a material that can freely set the band structure, dielectric constant, refractive index, electrical conductivity, electron affinity, ionization potential, and the like, which are the physical properties of the constituent materials required for superlattice material design. was there.

[0009] Further, in the point of the thin film structure, since the crystallinity of the material is low, the electronic state does not spread in one layer, or there is no coherence based on the periodic order in the electronic excitation. was there. In a superlattice material, in order for electrons and holes to effectively confine electrons in quantum wells and to cause resonance between wells, it is necessary that their electronic states have a spatial spread. is there. In order to express such an electronic state, it is necessary that the electronic states of the individual molecules interact sufficiently to form a band structure. Sex is required.

Another problem is that no interface is formed between different kinds of materials required for forming quantum wells and inducing resonance between the wells, the interface being smooth and having rapidly changing physical properties. Was. For that purpose, the material forming the interface is crystalline, and it is necessary to match the lattice constant between them.

There is another problem that the organic superlattice thus produced has poor structural stability.

Further, a high-speed transistor using an organic superlattice material has not been obtained at present.

[0013]

Further, an optical switching element using an organic superlattice material and capable of high-speed switching and having a large switch ratio has not been obtained at present.

Further, no logic device using an organic superlattice material, capable of high-speed response and exhibiting bistability with respect to the intensity of input light has been obtained at present.

[0016]

According to a first aspect of the present invention, there is provided an organic material comprising at least two layers of at least two kinds of organic thin films having a thickness of 0.5 to 100 mm. The present invention relates to an organic superlattice material in which any one of the kinds of organic thin films has a fundamental skeleton of a molecule constituting the thin film containing a π-conjugated linear oligomer shown below .

[0017] The repeating units of put that before Symbol π-conjugated linear oligomers in the present invention, the general formula (I):

[0018]

Embedded image (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II):

[0019]

Embedded image (Where Y is S, -CH = CH-, NH, NC
H ₃ , Se or O, R ³ , R ⁴ are the same or different,
H, an alkyl group having 1 to 3 carbon atoms or 1 carbon atom
Aromatic group (II) represented by the following formulas:
Or one or more of the following, or a general formula (III):

[0020]

Embedded image (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). One or more aromatic molecular groups (III), wherein the molecular chain end of the oligomer is H, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an azide group, a phenyl group,

[0021]

Embedded image Or those which are two of them.

In a second aspect of the present invention, the π-conjugated linear oligomer is represented by the general formula (I):

[0023]

Embedded image (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II):

[0024]

Embedded image (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following or a general formula (III):

[0025]

Embedded image (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The present invention relates to an alternating copolymer comprising two or more of one or more aromatic molecular groups (III).

According to a third aspect of the present invention, the π-conjugated linear oligomer is represented by the general formula (I):

[0027]

Embedded image (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II):

[0028]

Embedded image (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following formulas or the general formula (III):

[0029]

Embedded image (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The present invention relates to a block copolymer comprising two or more aromatic molecular groups (III).

In a fourth aspect of the present invention, the π-conjugated linear oligomer is represented by the general formula (I):

[0031]

Embedded image (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II):

[0032]

Embedded image (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following formulas or the general formula (III):

[0033]

Embedded image (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The basic thin film comprising one or more of the aromatic molecular groups (III) and constituting the organic superlattice is a π-conjugated linear oligomer of the single aromatic molecular group 2
The present invention relates to a mixed thin film composed of at least one kind of a thin film, which is formed by laminating one or two or more thin films having different composition ratios from the basic thin film.

In a fifth aspect of the present invention, the π-conjugated linear oligomer is represented by the general formula (I):

[0035]

Embedded image (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II):

[0036]

Embedded image (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following or a general formula (III):

[0037]

Embedded image (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The basic thin film that is composed of different aromatic molecular groups of the aromatic compound (III) and that constitutes the organic superlattice is a mixed thin film composed of two or more kinds of π-conjugated linear oligomers of the different aromatic molecular groups. In addition, the present invention relates to a device formed by laminating one or two or more thin films having different composition ratios from the basic thin film.

The sixth invention of the present invention relates to the invention, wherein each of the organic thin film layers comprises a crystal of a π-conjugated linear oligomer.

A seventh invention according to the present invention relates to the above-mentioned two or more kinds of organic thin-film layers, wherein a difference in lattice constant between organic thin-film layers having different compositions is within 10%.

According to an eighth aspect of the present invention, in the organic thin film layer, the molecular weight of the π-conjugated linear oligomer in the organic thin film layer is increased by polymerizing or crosslinking between molecules. About.

In a ninth aspect of the present invention, the organic thin film layer induces a chemical reaction in the π-conjugated linear oligomer existing at the interface of the organic thin-film layer, and the π-conjugated linear oligomer between the thin films is formed. It relates to a product obtained by polymerizing an oligomer.

According to a tenth aspect of the present invention, the organic thin film layer is irradiated with external light, radiation or electron beam,
The present invention relates to inducing a photochemical reaction to polymerize or crosslink molecules in the organic thin film layer to increase the molecular weight.

According to an eleventh aspect of the present invention, the organic thin film layer is irradiated with external light, radiation or electron beam,
The present invention relates to inducing a photochemical reaction to polymerize the π-conjugated linear oligomer between or in thin films.

Further, a twelfth aspect of the present invention provides:
The present invention relates to a high-speed transistor including a substrate and the organic superlattice material.

[0045]

Further, a thirteenth aspect of the present invention provides:
The present invention relates to an optical switching element including a substrate and the organic superlattice.

Further, a fourteenth aspect of the present invention provides:
The present invention relates to an optical bistable device including a substrate and the organic superlattice material.

[0048]

The π-conjugated linear oligomer material which is the basis of the organic superlattice material according to the first aspect of the present invention includes one of the above-mentioned general formulas (I), (II) and (III).
What is necessary is just to consist of a kind or two or more kinds of aromatic molecular groups. The number of the molecular groups constituting the linear oligomer is not particularly limited, but may be a solid state at room temperature,
From the viewpoint of having a sufficient π-conjugated electron spread,
Three or more are preferred. In addition, it is desirable to control the structure of the thin film to be produced, that the two or more kinds of π-conjugated linear oligomers constituting the mixed thin film should have the same spatial shape and size when formed, The number of the molecular groups of the π-conjugated linear oligomer used is preferably 10 or less from the viewpoint that the molecular weight dispersion is likely to occur and the separation is not easy if the number of the molecular groups increases upon the synthesis of the compound.

Further, considering the ease of synthesis, the sufficient spread of π-conjugated electrons, the ease of handling materials at room temperature, and the controllability of the structure at the time of forming a thin film, from 5 to 8 molecules of the molecule A π-conjugated linear oligomer having a group number is preferred.

A typical example will be described.

For example,

[0052]

Embedded image A hexamer of an oligothiophene (compound (1)) in which a thiophene ring represented by

[0053]

Embedded image FIG. 1 shows an energy level diagram in the film thickness direction of a laminated thin film composed of an oligophenylene hexamer (compound (2)) having a benzene ring bonded in a linear manner. In FIG. 1, 1 indicates a conduction band and 2 indicates a valence band. FIG. 1 shows that this laminated film is a type 1 superlattice. See “Physics and Applications of Semiconductor Superlattices” 2
4 pages (edited by The Physical Society of Japan, published by Baifukan (1984))
It is described in. The potential perceived by electrons in the conduction band or holes in the valence band of the superlattice system is approximately represented by a well-type potential. Phenylene is a barrier. The height of the barrier corresponds to the discontinuity of the energy band in the conduction band and the valence band at the hetero interface between the two semiconductors. Here, if the thickness of the oligothiophene, which is a well, is sufficiently larger than the thickness of oligophenylene, which is a barrier, electrons cannot cross the barrier and are localized near the well. As a result, the electrons are confined in the oligothiophene layer, and the density of states is quantized because the electrons are bound in a specific space. As a result, a quantum effect that cannot be seen in the case of bulk is developed.

The organic superlattice having the quantum well-like electronic state shown in FIG. 1 is mainly composed of a vacuum evaporation method such as an organic molecular beam evaporation method, an organic ion cluster beam evaporation method, an electrolytic polymerization method, or the like.
Langmuir-Blodget (Langmuir-Blo
dgett) method.

As the substrate in the present invention, a quartz plate, an amorphous substrate such as a slide glass, potassium bromide,
Examples include an alkali halide single crystal plate such as sodium chloride and potassium chloride, a silicon wafer, and a plate obtained by depositing a metal such as gold, silver, or aluminum on these substrates.

The thickness of the organic thin film in the present invention is 0.5
If the film thickness is less than 0.5 nm, it cannot be manufactured because it is smaller than the molecular size, and if it exceeds 100 nm, there is a tendency that specific physical properties due to thinning do not appear. is there.

It is preferable to use at least two kinds of organic thin films in the present invention, and it is more preferable to use 2 to 4 kinds of organic thin films from the viewpoint of developing new physical properties.

It is preferable that at least two layers of the organic thin film in the present invention are laminated, and it is more preferable to use 2 to 50 layers from the viewpoint of effectively exhibiting characteristics.

In the present invention, since a π-conjugated linear oligomer is used as a constituent molecule of the superlattice material, deterioration of characteristics due to dispersion of molecular weight which occurs when a polymer is used can be suppressed. It is possible to design the material properties of the basic constituent film by the combination of the materials described above, thereby enabling the material design and production of the organic superlattice by effectively utilizing the effect of π electrons.

[0060] and put that π-conjugated linear oligomers to the present invention, the general formula (I), (II) or aromatic molecular group represented by (III) (I), (II) or (II
I) can be suitably used.

By using a π-conjugated linear oligomer composed of the aromatic molecular group represented by the general formula (I), (II) or (III) as the basic skeleton of the superlattice material, The band structure, conductivity, dielectric constant, refractive index, electron affinity, ionization potential, and the like, which are the basic physical properties of, can be freely controlled, and a wider material design of the organic superlattice than before can be made possible.

Preferred examples of the general formula (I) include, for example,

[0063]

Embedded image And so on.

Preferred specific examples of the general formula (II) include, for example,

[0065]

Embedded image And so on.

Preferred specific examples of the general formula (III) include, for example,

[0067]

Embedded image And so on.

In the second and third aspects of the present invention, the molecular group constituting the π-conjugated linear oligomer is selected from the aromatic groups represented by the general formula (I), (II) or (III). By using an alternating copolymer or a block copolymer composed of the two types of components described above, it is possible to control basic physical properties that cannot be obtained with a random copolymer such that the physical properties of the material are uniform over the entire molecule. The material design of the organic superlattice can be made possible.

Preferred specific examples of the alternating copolymer include:

[0070]

Embedded image And so on.

In the fourth and fifth aspects of the present invention, the basic skeleton of the π-conjugated linear oligomer is an aromatic moiety which is a basic moiety of the general formula (I), (II) or (III). Is a single component, or a homo-oligomer in which an alkyl group or an alkoxy group is bonded to a single component, or a co-oligomer of a different component is used, and the basic constituent thin film is composed of two or more homo-oligomers or co-oligomers. It is a mixed film, and by alternately laminating them, it is possible to freely control the physical properties of the thin film such as band structure, conductivity, dielectric constant, refractive index, electron affinity, ionization potential, etc. Can be made widely possible.

Further, the mixed thin film using two or more kinds of oligomers composed of the single component can be used, for example, in view of the difference in relative energy between the valence band and the conduction band.

[0073]

Embedded image Are preferred.

When a plurality of thin films having different composition ratios are stacked, a combination of the above compounds, for example, 80:20 and 20:80 is preferable from the viewpoint of effectively forming a well layer.

In the sixth aspect of the present invention, the π-conjugated linear oligomer is used as a basic molecule having the organic thin film as a constituent molecule, and its structure is made crystalline. Is spread, and the quantum confinement effect can be effectively induced when the superlattice structure is manufactured, and the effect of the superlattice structure can be effectively exhibited.

In order to obtain a crystal, it is preferable to form a film by a dry process such as a molecular beam evaporation method or an ion beam evaporation method from the viewpoint of obtaining a sharp composition change.

In the seventh aspect of the present invention, the difference in lattice constant at the interface between dissimilar materials of the basic constituent thin film is set to 10% or less, so that epitaxial growth and strained epitaxial growth at the interface are enabled, and phase matching of the lattice is achieved. By taking the above, an organic superlattice can be manufactured without generating voids in the spatial structure of the material or generating a large barrier in the band structure of electrons.

In the eighth aspect of the present invention, in order to polymerize between the molecules of the π-conjugated linear oligomer, a photoactive substituent may be bonded to the molecular terminal from the viewpoint of polymerization by a photochemical reaction. For crosslinking, a reactive group may be bonded to the molecular chain from the viewpoint of crosslinking by a photochemical reaction. The molecular weight of the polymer after polymerization or cross-linking is 200 points from the viewpoint of quantum effect development and material stability.
It is preferably from 10,000 to 10,000.

In the ninth aspect of the present invention, it is preferable that the oligomer is caused to undergo a chemical reaction to be polymerized to make the interface between different thin films continuous in terms of stabilization of the superlattice structure as compared with a single layer. Later molecular weight is 200-10000
Is preferable from the viewpoint of material stabilization.

In the tenth aspect of the present invention, the oligomer may be irradiated with light, radiation or an electron beam as a method of polymerizing or crosslinking. However, the irradiation energy intensity is low since the material does not induce a morphological change. Preferably less than 1 megawatt.

In the eighth and tenth aspects,
The π-conjugated linear oligomer in the basic thin film is irradiated with external light, radiation or electron beam to induce a chemical reaction in the molecule to polymerize or crosslink, forming a wider band structure. , And also enhance the stability of the material.

In the eleventh invention of the present invention, the oligomer may be polymerized by irradiating light, radiation or an electron beam, but the irradiation energy intensity is preferably 1 megawatt or less from the viewpoint that no morphological change is induced in the material. .

In the ninth and eleventh aspects of the present invention, the π-conjugated linear oligomer at the interface between the different types of thin films of the basic constituent thin film is irradiated with external light, radiation or an electron beam to allow the heterogeneous molecules at the interface between the different types of molecules. By inducing a chemical reaction and polymerizing, the band structure at the interface between different thin films becomes continuous, and the stability of the material can be enhanced.

In the twelfth aspect of the present invention,
The thickness of the well layer is 5 to 10 nm, and the thickness of the barrier layer is 10 to 1
It is preferable to use a thin film in which about 10 layers are alternately laminated at 00 nm.

A high-speed transistor is manufactured using the above-mentioned organic superlattice material, and the carrier mobility, which is a device characteristic, can be improved.

[0086]

[0087]

In the thirteenth aspect of the present invention,
Since a superlattice material is used for the optical waveguide layer, it is preferable to select a compound that has a small absorption and a small optical scattering in the wavelength region of the light to be guided, and thins the compound.

An optical switch is manufactured using the above-mentioned organic superlattice material, and the modulation speed and the switching ratio, which are device characteristics, can be improved.

In a fourteenth aspect of the present invention,
Since a bistable characteristic can be obtained by irradiation with an external laser, it is preferable to select a material that does not absorb light in the irradiation laser wavelength region and has a small optical scattering, and is formed into a thin film.

An optical bistable element is manufactured by using the above-mentioned organic superlattice material, and it is possible to reduce a threshold light intensity value as a device characteristic and to improve a bistable characteristic.

Next, the organic superlattice material of the present invention, a method for producing the same, and a device using the material will be described in detail with reference to Examples, but the present invention is not limited thereto.

[Example 1] (Production of organic alternately laminated film)

[0094]

Embedded image A compound (1) represented by

[0095]

Embedded image Are placed in separate quartz crucibles and set in a heating cell in a vacuum layer.
A synthetic quartz plate of 0 mm × 40 mm × 1 mm was put in a vacuum layer and evacuated. After the degree of vacuum reaches 10 ^-9 Torr, the two cells are alternately heated to 1
Under the condition of a deposition rate of A / min or less, compound (2)
Compound (1) was deposited on the substrate so as to have a thickness of 5 nm and a thickness of 15 nm, and 17 layers were repeatedly laminated. The first
The layer was compound (2). In the present laminated film, the compound (1) becomes a well layer and the compound (2) becomes a barrier layer.

[Example 2] (Superlattice effect using oligomer) The powders of the compound (1) and the compound (2) used in Example 1 were put in separate quartz crucibles, and heated cells in a vacuum chamber Set to 25mm × 40mm × 3mm
Was placed in a vacuum chamber and evacuated. After the degree of vacuum reaches 10 ⁻⁹ Torr, the two cells are alternately heated, and the thickness of the compound (2) is set to 10 mm and the thickness of the compound (1) is set to 5 nm at a deposition rate of 1 A / min or less. Deposited on the substrate so that
Zero layers were laminated. The first layer was the compound (2). In this laminated film, compound (1) becomes a well layer and compound (2) becomes a barrier layer.

FIG. 2 shows an ultraviolet-visible absorption spectrum of the laminated thin film produced. In this figure, the horizontal axis represents the energy (eV) of the absorbed light, and the vertical axis represents the absorbance. FIG. 2 (I) shows an absorption spectrum of the laminated film manufactured in this example, and FIG. 2 (II) shows a 1000A formed on a synthetic quartz plate.
(IV) is the absorption spectrum of the compound (2) single film of 500A formed in a synthetic quartz plate shape. As shown in FIG. 2, the peak of the compound (1) was shifted to a higher energy than in the case of the single film, and it was found that the quantum effect due to the formation of the superlattice appeared.

[Examples 3 to 33] As shown in Table 1, using the combination of the compounds represented by the general formulas (I), (II) and (III), the layers were laminated in the same manner as in Example 2, When the absorption spectrum of the laminated film was measured, it was found that in each case, the energy shift was higher than the absorption peak of the single film of the well layer, and a quantum effect due to the formation of a superlattice appeared.

[0099]

[Table 1]

[0100]

[Table 2]

[0101]

[Table 3]

[0102]

[Table 4] [Example 34] (Copolymer of two or more oligomers)

[0103]

Embedded image Compound (3) represented by

[0104]

Embedded image The powders of the block copolymer oligomers having different composition ratios of thiophene and pyrrole contained in the molecular structure represented by the compound (4) represented by are placed in separate quartz crucibles and set in a heating cell in a vacuum chamber. . Further, gold used as a gate electrode is deposited on a surface of 30 nm by a vacuum evaporation method, and SiO ₂ used as an insulating film is deposited at a thickness of 300 nm by a sputtering method.
A synthetic quartz plate having a thickness of 2 mm was placed in a vacuum chamber and evacuated. After the degree of vacuum reaches 10 ^-9 Torr, the cell is heated, and the layers are alternately deposited on the substrate so that the thickness of each layer becomes 10 nm under the condition that the deposition rate is 1 A / min or less. A laminated thin film was prepared. Further, 30 nm of gold serving as a gate electrode or a drain electrode was vapor-deposited on the manufactured thin film to manufacture a staggered field effect transistor element shown in FIG. Here, 10 is a quartz substrate, 11 is a gate electrode, 12 is an insulating film, 13 is an organic superlattice layer composed of 10 layers, 14 is a source electrode, and 15 is a drain electrode.

When a negative electric field was applied to this cell to measure the FET characteristics, the characteristics shown in FIG. 4 were obtained. FIG.
In the graph, the horizontal axis represents the voltage value between the source electrode and the drain electrode,
The vertical axis indicates the current value between the source electrode and the drain electrode. The voltage applied to the gate electrode was -40V. Here, (IV) is the characteristic of the FET device manufactured according to the present embodiment,
(V) is

[0106]

Embedded image 2 shows characteristics of a staggered FET device using a random copolymer of oligothiophene pyrrole (compound (5)) shown in FIG.

As shown in FIG. 4, it was found that the FET characteristics of the organic superlattice produced in this example were improved as compared with the random copolymer.

[Examples 35 to 64] As shown in Table 2,
Using a combination of the compounds represented by the general formulas (I), (II) and (III), lamination was performed in the same manner as in Example 23, and the electrical conductivity of the laminated film was measured. It was also found that the electrical conductivity of the random copolymer thin film was higher than that of the random copolymer thin film.

[0109]

[Table 5]

[0110]

[Table 6]

[0111]

[Table 7]

[0112]

[Table 8] [Example 65] (Lamination of thin films having different mixing ratios with oligomer composed of a single component) Compound (1) and compound (2) used in Example 1
Were placed in separate quartz crucibles and set in a heating cell in a vacuum chamber. Next, gold used as a gate electrode was deposited in a thickness of 30 nm, and SiO ₂ used as an insulating film was deposited thereon in a thickness of 300 nm.
A 1 mm synthetic quartz plate was placed in a vacuum chamber and evacuated. After the vacuum reaches 10 ^-9 Torr, 2
The two cells were simultaneously heated to form a mixed thin film of compound (1) and compound (2) on the substrate. At this time, compound (1)
The temperature of each crucible was adjusted such that the mixing ratio of the compound and the compound (2) was 2: 8. The thickness was 50 nm.

Next, the temperatures of the two crucibles were changed and the temperatures of the respective crucibles were adjusted so that the mixing ratio of the compound (1) and the compound (2) became 9: 1. The laminated film was produced by depositing on the thin film. The thickness of this layer is 1
It was set to 0 nm.

The above operation was further repeated to produce a 10-layer organic superlattice having a mixing ratio of 2: 8 and 9: 1. In this case, the layer having a mixing ratio of 2: 8 is a barrier layer, and the mixing ratio is 9: 8.
One layer becomes a well layer.

Next, on the 10-layer laminated film, gold serving as a source electrode or a drain electrode was vapor-deposited in a thickness of 30 nm to produce a staggered FET device as shown in FIG. In FIG. 5, 20 is a substrate, 21 is a gate electrode, 22 is an insulating film, 23
Is a barrier layer, 24 is a well layer, 25 is a source electrode, and 26 is a drain electrode. When the FET characteristics of this device were measured, it was found that the characteristics were improved as compared with the FET of the compound (1) or the compound (2) alone thin film.

Examples 66 to 75 As shown in Table 3,
Using a combination of the compounds represented by the general formulas (I), (II) and (III), a mixed film was laminated in the same manner as in Example 44, and the electric conductivity of the laminated film was measured. In this case, the characteristics were improved as compared with the electric conductivity of each single thin film, and it was found that the quantum effect due to the formation of the superlattice appeared.

[0117]

[Table 9]

[0118]

[Table 10] [Example 76] (Crystal superlattice) When a laminated thin film was prepared using compound (1) and compound (2) powders as raw materials shown in Example 2, the substrate temperature during deposition was set to 100 ° C. 90% crystallinity of each layer
Improved.

Using this laminated film, a staggered field-effect transistor was fabricated in the same manner as in Example 2, and the electrical characteristics were measured. The characteristics were better than those in Example 2. This is considered to be due to the fact that the number of grain boundaries serving as trap sites when carriers move is reduced due to improvement in crystallinity. Thus, the effect of the superlattice can be further improved by improving the crystallinity of each thin film layer.

[Example 77] (Epitaxially grown superlattice)

[0121]

Embedded image An oligopyrrole hexamer (compound (6)) represented by

[0122]

Embedded image When a laminated thin film was prepared in the same manner as described in Example 55 using the oligofuran hexamer (compound (7)) represented by the following formula, a thin film in which the crystallinity of each layer was 98% was obtained. Was completed. The difference in lattice constant between these compounds is about 8
%, It was found that pseudo-epitaxial growth was caused by the effect of the Van der Waals force peculiar to the organic substance.

Example 78 (Photochemical Intramolecular Polymerization Reaction) On a potassium bromide (KBr) 001 single crystal substrate having a size of 15 mm × 15 mm × 3 mm, an organic molecular beam evaporation method was used.

[0124]

Embedded image After depositing the substance shown in (20) (compound (8)) by 20 nm,

[0125]

Embedded image (Compound (9)) was laminated in a thickness of 10 nm. This operation was repeated to produce a laminated thin film composed of 10 layers. The thin film was irradiated with excimer laser light having a wavelength of 351 nm (energy per pulse: 1 mJ / cm ² ) so that the total amount of light was 5 J / cm ² . FIG. 6 shows a comparison of the infrared absorption spectra of this thin film before and after irradiation. In FIG. 6, (VI) indicates before irradiation, and (V) indicates
II) is the spectrum after irradiation. It can be seen that the absorption attributable to the azo bond at around 1500 cm ^-1 is increased, while the absorption attributable to the azide group at 2300 cm ^-1 is significantly reduced. From this, it was found that the compound (9) caused a polymerization reaction by light irradiation.

Example 79 (Photochemical interlayer polymerization reaction) On a potassium bromide (KBr) 001 single crystal substrate having a size of 15 mm × 15 mm × 3 mm, an organic molecular beam evaporation method was used.

[0127]

Embedded image (Compound (10)) shown in the above was deposited to a thickness of 10 nm, and then

[0128]

Embedded image (Compound (11)) was laminated in a thickness of 5 nm. This operation was repeated to produce a laminated thin film composed of 20 layers. An excimer laser beam having a wavelength of 248 nm (energy per pulse: 1 mJ / cm ² ) is applied to this thin film.
Was irradiated so that the total amount of light was 4 J / cm ² . FIG. 7 shows a comparison of the infrared absorption spectrum of the thin film after irradiation. Compared to the absorption is lost attributable to an azide group 2300 cm ^-1, 1500 cm ^-1
The absorption attributed to nearby azo bonds has increased significantly. From this, it was found that the compound (10) and the compound (11) caused a polymerization reaction by light irradiation.

[Example 80] (Organic HEMT device) Compound (1) was deposited to a thickness of 100 nm on a 3-inch n-type silicon plate by the organic molecular beam evaporation method used in Example 1, and then was placed thereon.

[0130]

Embedded image A 10-nm methoxy oligochenylene vinylene trimer (compound (12)) was deposited to form a laminated film. Next, a 50 nm-thick aluminum electrode was provided on the laminated film using a normal vacuum deposition method to form a gate electrode,
Further, a gold electrode having a thickness of 50 nm was provided to form a source electrode and a drain electrode. Thus, the transistor element shown in FIG. 8 was obtained. In this case, the channel layer is the compound (1), and the methoxy oligotunylene vinylene trimer functions as a carrier injection layer. In FIG. 8, 30
Is a substrate, 31 is a compound functioning as a channel layer (1)
Compound (1) that functions as a thin film, 32 carrier injection layer
2) Thin film, 33 is a source electrode, 34 is a gate electrode, 35
Is a drain electrode.

Next, the electrical characteristics of this device are shown in FIG.
In this figure, the horizontal axis is the source-drain voltage (V _DS ), and the vertical axis is the source-drain current ( _IDS ). When the gate voltage (VG) is 0 V, V
_Although I _DS hardly flows even if _DS increases, a positive V
_{When G} is applied, a large I _DS flows.
Moreover, in a region where V _DS is large, saturation of I _DS was observed, and typical transistor characteristics were obtained. Shows the conventional compound (1) alone film electrical characteristics when (thickness 500 nm) only was used in the active layer by a dotted line in FIG. 9, the same V _DS
Even when I was applied, the transistor fabricated this time had larger _IDS flowing, and a transistor with higher carrier mobility could be obtained.

[Example 81] (Organic crystal HEMT device) In the process of forming a thin film described in Example 80, a film was formed at a substrate temperature of 100 ° C during deposition. The degree of crystallization is improved, and the degree of crystallization is 86.
% Of the laminated film could be produced. When the FET characteristics of this thin film were measured in the same manner as in Example 80, an element having further improved carrier mobility could be manufactured.

[ Reference Example ] (Light Modulating Element) After depositing 30 nm of gold on a LaSF9 substrate of 20 mm × 10 mm × 1 mm, the organic molecular beam deposition method was applied to the entire substrate.

[0134]

Embedded image Was vapor-deposited to a thickness of 100 nm, and gold was vapor-deposited on the center of the substrate to a thickness of 30 nm by an ordinary vacuum vapor deposition method. Two triangular prisms made of sapphire were pressed against this thin film to obtain an element having the structure shown in FIG. In FIG. 10, 40 is an optical waveguide layer made of the compound (13), 41 is an electrode film,
Numeral 2 is a prismatic prism, and numeral 43 is a substrate. A laser diode light having a wavelength of 833 nm was incident on one of the prisms to guide the light into the thin film, and the guided light was extracted by the other prism.

[0135] was applied an alternating electric field of a sine wave of 1 kH _Z between the gold electrodes in the device, the output light in response to the electric field intensity as shown in FIG. 11 is changed. As described above, an optical switch could be manufactured by this method.

Example 82 (Optical Switch Element) After depositing 30 nm of gold on a LaSF9 substrate of 20 mm × 10 mm × 1 mm (FIG. 12 (a)), the organic molecular beam deposition method was used.

[0137]

Embedded image The oligophenylenedithiophene dimer (compound (14)) represented by the following formula is 80 nm, and the compound (13) is 20 nm.
Was deposited (FIG. 12B). A pattern of a Mach-Cheander element was formed on the laminated film by using a conventionally known lithography technique (FIG. 12).
(C)). Further, a siloxane polymer (trade name “Ladder Polymer”, manufactured by Ryoden Kasei Co., Ltd.) was applied thereon to a thickness of 1 μm by a spin coat method, and then 30 nm of gold was deposited again on the position shown in FIG. A Mach-Cheander type waveguide device was manufactured. FIG. 13 is a cross-sectional view taken along line AA of FIG. Here, the cross section of the waveguide film was 500 μm × 300 μm. 5 in FIGS. 12 and 13
0 is an organic thin film which is an optical waveguide film of the compound (14);
Is a gold electrode film, 52 is a siloxane polymer film (insulating film),
Reference numeral 53 denotes a substrate.

A laser diode light having a wavelength of 833 nm is incident from the end face of this element, and 1 KH is applied between the gold electrodes.
When an AC electric field of a sine wave of z was applied, the intensity of the output light changed according to the electric field intensity as shown in FIG. As described above, an optical switch could be manufactured by this method.

[Example 83 ] (Optical bistable element) A phenylene octamer represented by the compound (8) was deposited to a thickness of 20 nm on a 20 mm x 10 mm x 1 mm quartz glass substrate by an organic molecular beam evaporation method. An octameric thiophene represented by the compound (9) was deposited thereon to a thickness of 10 nm. This operation was repeated 10 times to produce an organic superlattice thin film element having a thickness of 2000 nm. The sample was irradiated from the vertical direction with continuous oscillation laser light having a wavelength of 830 nm obtained by combining an argon ion laser and a dye laser, and transmitted light was detected by a high-speed photodiode.
The incident light was modulated at a high frequency of 1 GHz by a high-speed optical modulator and a part was taken out as a trigger. Connect the trigger of the incident light and the output of the transmitted light to the XY of the oscilloscope,
When the Lissajous figure was plotted, the bistable characteristic shown in FIG. 15 was obtained. The operating power at this time was on the order of mW, and a low threshold and high-speed response bistable element was obtained.

[0140]

According to the present invention, an organic superlattice is produced by using a π-conjugated linear oligomer, and by using this organic superlattice material, a transistor having a higher carrier mobility than conventional ones, and It has become possible to provide an optical device having excellent non-linear optical characteristics, such as an optical switch and an optical bistable element.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a band structure of an organic superlattice composed of a compound (1) and a compound (2).

FIG. 2 is an ultraviolet-visible absorption spectrum of an organic superlattice thin film comprising a compound (1) and a compound (2).

FIG. 3 is a schematic sectional view of a staggered field effect transistor element.

FIG. 4 shows an organic superlattice thin film FET described in Example 23.
6 is a graph showing transistor characteristics of the device.

FIG. 5 is a schematic cross-sectional view of a staggered field effect transistor device using the laminated organic superlattice thin film described in Example 44.

FIG. 6 is an infrared absorption spectrum of the thin film described in Example 57.

FIG. 7 is an infrared absorption spectrum of the thin film described in Example 58.

FIG. 8 is a schematic cross-sectional view of the HEMT field effect transistor element described in Example 59.

FIG. 9 is an HEM of the organic superlattice thin film described in Example 59.
6 is a graph showing transistor characteristics of a T element.

FIG. 10 is a schematic sectional view of a prism-coupled light modulation element.

FIG. 11 is a graph showing light modulation characteristics of a prism-coupled light modulation element.

FIG. 12 is a conceptual diagram of a manufacturing process of a Mach-Zehnder optical switch.

FIG. 13 is a schematic sectional view of a Mach-Zehnder switch.

FIG. 14 is a graph showing light modulation characteristics of a Mach-Zehnder light switch.

FIG. 15 is a graph showing characteristics of the optical bistable element.

FIG. 16 is a schematic sectional view of a conventional organic superlattice.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Shinji, Inventor 8-1-1 Tsukaguchi Honcho, Amagasaki City Inside the Materials and Devices Laboratory, Mitsubishi Electric Corporation (72) Inventor Chie Fukada 8-1-1, Tsukaguchi Honmachi, Amagasaki City No. Mitsubishi Materials Corporation Materials and Devices Laboratory (72) Inventor Yasuyasu Nakao 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Materials and Devices Laboratory (56) References Electrical, Optical, and Magnetic Pro parties of Organic Solid State Material ials, vol. 328 (1994) p. 389-393 Mol. Cryst. Liq. Cry st. , Vol. 256 (1994) p. pp. 481-486 (58) Field surveyed (Int. Cl. ⁶ , DB name) G02F 1/35 504 JICST file (JOIS)

Claims (14)

(57) [Claims] 1. A film thickness is formed by laminating at least two layers of at least two organic thin film of 0.5 to 100 nm, the at least in any of the two organic thin film, the molecules constituting the thin film In an organic superlattice material whose basic skeleton contains a π-conjugated linear oligomer, the π-conjugated linear oligomer is used .
Repeating units of Goma is, the general formula (I): 1] (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more of the aromatic molecular groups (I) represented by
Moreover, the general formula (II): ## STR2 ## (Where Y is S, -CH = CH-, NH, NC
H ₃ , Se or O, R ³ , R ⁴ are the same or different,
H, an alkyl group having 1 to 3 carbon atoms or 1 carbon atom
Aromatic group (II) represented by the following formulas:
One or more of the general formula (III): ## STR3 ## (Where Z is N or CH, R ⁵ , R ⁶ and R ⁷ are the same
Or different, respectively, H, an alkyl group having 1 to 3 carbon atoms
Or an alkoxy group having 1 to 3 carbon atoms)
An oligomer comprising one or more of molecular groups (III), wherein the oligomer has a molecular chain terminal of H and an alkyl having 1 to 3 carbon atoms.
Group, alkoxy group having 1 to 3 carbon atoms, azide group, phenyl
Group, ## STR4 ## Or an organic superlattice material which is two of them . 2. The π-conjugated linear oligomer is represented by the general formula (I): (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II): (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following formulas or the general formula (III): (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The organic superlattice material according to claim 1 , wherein the organic superlattice material is an alternating copolymer comprising two or more of one or more aromatic molecular groups (III). 3. The π-conjugated linear oligomer is represented by the general formula (I): (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II): (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following formulas or the general formula (III): (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). A block copolymer comprising two or more of aromatic aromatic groups (III).
2. The organic superlattice material according to 1. 4. The π-conjugated linear oligomer is represented by the general formula (I): (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II): (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the following or general formula (III): (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). The basic thin film comprising one or more of the aromatic molecular groups (III) and constituting the organic superlattice is a π-conjugated linear oligomer of the single aromatic molecular group 2
2. The organic superlattice material according to claim 1, wherein the organic superlattice material is a mixed thin film composed of at least one kind, and is formed by laminating one or two or more thin films having different composition ratios from the basic thin film. 5. The π-conjugated linear oligomer is represented by the general formula (I): (Wherein, X is S, N-H, N- CH 3, Se or O,
R ¹ and R ² are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (I) represented by the general formula (II): (Wherein, Y is S, N-H, N- CH 3, Se or O,
R ³ and R ⁴ are the same or different and each have H, carbon number 1
Alkyl group or alkoxy group having 1 to 3 carbon atoms)
One or more aromatic molecular groups (II) represented by the general formula (III): (Wherein, Z is N or C—H, R ⁵ , R ⁶ , and R ⁷ are the same or different and each is H, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms). A mixed thin film comprising a heterogeneous aromatic molecular group of the aromatic molecular groups (III), wherein the basic thin film constituting the organic superlattice comprises two or more kinds of π-conjugated linear oligomers of the heterogeneous aromatic molecular group And wherein one or more thin films having different composition ratios from the basic thin film are laminated.
The organic superlattice material as described. 6. The organic superlattice material according to any one of claims 1 to 5 consisting of the even organic thin film layer either π-conjugated linear oligomer crystals. 7. The said two or more organic thin film layer, an organic superlattice material according to any one of claims 1 to 6 difference in lattice constant of the organic thin film layer is within 10% with different compositions. Wherein said organic thin film layer, claim 1-7 in which the intermolecular of the π-conjugated linear oligomers of the organic thin film layer polymerization or by crosslinking consisting of those obtained by molecular weight 3. The organic superlattice material according to 1.). 9. The method according to claim 1, wherein the organic thin film layer induces a chemical reaction on the π-conjugated linear oligomer present at the interface of the organic thin-film layer and polymerizes the π-conjugated linear oligomer between the thin films. An organic superlattice material according to any one of claims 1 to 7 . 10. The organic thin film layer is irradiated with external light, radiation or an electron beam to induce a photochemical reaction to polymerize or crosslink molecules in the organic thin film layer to increase the molecular weight. Item 10. The method for producing an organic superlattice material according to Item 8 . Wherein said light from the outside to the organic thin film layer, radiation or electron beam irradiation, claim comprising by inducing a photochemical reaction by polymerizing π-conjugated linear oligomer thin film between or within the thin film 9 A method for producing the organic superlattice material according to the above. 12. The substrate with the high-speed transistor comprising the organic superlattice material according to any one of claims 1-9. 13. The substrate with the optical switching element consisting of an organic superlattice material according to any one of claims 1-9. 14. The substrate with the optically bistable device comprising the organic superlattice material according to any one of claims 1-9.