JPS5946074A - Semiconductor thin film light emitting device - Google Patents

Abstract

PURPOSE:To obtain the desired light emitting colors by a method wherein the impurities forming the intermediate energy level are added in the layers with large Eg holding the active layer with small forbidden band width Eg. CONSTITUTION:A transparent electrode 2, a ZnS layer 3 doped with the impurities forming the preferable intermediate energy order, a ZnSe active layer 4, another doped ZnS layer 5 and a backside electrode 6 are laminated on a glass plate 1. At this time, a quantum well QW is formed enclosing electrons and holes in the active layer 4 with small Eg facilitating light emission and recoupling improving the driving voltage. Moreover the quantity of the excited electrons is increased due to the intermediate energy order formed further improving the light emitting efficiency. Besides assuming the thickness of the active layer to be L and the effective mass of the electrons and holes to be me, mh, the substantial Eg equals to the value as follows i.e. Eg=Eg(ZnSe)+h<2>/2me.(pi/L)<2>+ h<2>/2mh.(pi/L)<2>. Thus, all of the intermediate colors of the proper light emitting colors may be produced by means of changing L into Eg (ZnSe)<Eg<Eg(ZnS).

Description

Detailed Description of the Invention Field of Application of Industry-1 The present invention relates to a novel conductor thin film light emitting element r, and in particular, it is capable of emitting light of any desired color, and is suitable for use in JV small devices.・1' no 11 light, 48 ryo-to L te 11 a
Thealni Mlit 'F-;A f*? 't+
It is intended to provide nQ R: X, '4, j'.

Summary of the Invention The semiconductor thin film light emitting device of the present invention is a light emitting device using thin film layers of two types of semiconductors with a forbidden band width of 912 and a semiconductor thin film layer of 1111 and a small power semiconductor with a forbidden band width of 119 as an active +1 layer. The semiconductor thin film layer is laminated in a stacked manner by a semiconductor thin film layer with a larger forbidden band width, and is made of a conductor with a large force of the forbidden band width. It is characterized by adding an impurity that forms the n-position of energy between the two. By changing the thickness of the active layer appropriately, it is possible to create a light-emitting element that emits light with a different color, and also to increase the forbidden band width to >1', whichever is larger.
- Conductor (by adding an impurity that forms an energy level in the middle of the conductor 11, electrons are easily excited, and the light emitting efficiency is greatly improved.

EXAMPLES Below, details of the semiconductor thin film light emitting device of the present invention will be explained according to illustrated examples.

1 is a transparent substrate, which is a glass plate or silicon (St);
Galiuno 1-Arsenic (G a AS )', <consisting of a crystalline plate.

Reference numeral 2 denotes a transparent upper plate 1, which is made of a film of tin infusion, for example insilano, and is formed on one side of the transparent plate I.

3 is "I7: conductor p511Q, for example sulfide 1U1n (
ZnS) 100 to 1000 angstroms (person)
It is 11th thick of IV't. This 1'' conductor thin 11g layer is doped with an impurity that forms energy J(+(I1't) in the middle of the forbidden band of the 1'' conductor, which is the old tl.

4 is an active layer; 4 ILs?
'# IIA 3 is assembled together with the Ota.
'.

Conductor thin 11/j 3 to 1 of 3 The width of the conductor is 4W or smaller than the conductor material.For example, as mentioned above, if the semiconductor material of the ``1'' conductor thin film 3 is subsulfide (7'3 (: Z nS )) is 1F lead selenide (ZnS e) or Zn5
41~ items of xSe(1-X) are considered. And 2.
The thickness of the second active layer 4 is 10 to 2 QO ongest.

Reference numeral 5 denotes a conductor thin film made of a t-conductor material (ZnS in the above example) similar to the semiconductor material of the semiconductor thin film 3, which is heterojunctioned with the active layer 4, and has a layer thickness of 50 to 500 angstroms. De Al.

Even in this 1F>Q body I membrane layer 5, there is energy in the middle of the forbidden band of the 1' conductor which is its material! (An impurity forming the r: position is added.

Reference numeral 6 denotes a back electrode provided in contact with the back surface of the semiconductor thin film 5. This back electrode 6 can be transparent, translucent, achromatic, or
It may be colored or whatever is appropriate.

FIG. 2(A) is a cross-sectional view of the laminated body 7 consisting of the semiconductor thin films 3, 5 and the active layer 4, sliced thinly in the thickness direction, and FIG. 2(B) corresponds to (A). This shows the distribution of the two-orchie level in each layer.

As can be seen from Figure 2, forbidden: When a thin film made of a semiconductor material with a small width is sandwiched between thin films made of a semiconductor material with a larger forbidden band width, a quantum well QW is formed, and the forbidden band Electron r- and 11 holes are inserted into the layer of the smaller width 31'-conductor falling rock, and in order to perform luminous recombination here, the light emission with a wavelength of 31' is tII. According to the hanging J''' well structure, electrons and 11 holes are confined in the active layer 4 and are easily recombined by light emission, so that the luminous efficiency increases and, therefore, the driving IL pressure can be increased by 1. I can do it.

In addition, as shown in the ε63 diagram, the impurity added to the semiconductor film layer with a large force in the forbidden band forms an energy IG++ level in the middle of the forbidden band, so it is excited. increases, and the luminous efficiency further increases by -1.

That is, when no impurity is added, the excitation from the valence II to the conduction band is ll'i as shown by the arrow (a).
There is only one pump, and at least the energy equivalent to the forbidden band width must be obtained by the market. However, if an impurity is added to form a metal level in the forbidden band, the 11th level is stepped to the right and the conduction level from the valence r-band to f2 is 111. Excitement is encouraged.

The excitation process is one process with the lilil force shown by arrows (b+) and (b2), and each process (b
+), (b2) occur when the energies △El and △E2, which are smaller than the band width Eg, are transferred to electrons. Therefore, if the rotational energy is changed, the number of excited electrons will increase compared to the case where no impurity is added. Then, from the valence band to the conduction band, ili (iii, -f.

It is confined in the well QW, where light is emitted and coupled out.

Furthermore, according to the semiconductor thin film light emitting device r of the present invention, the active layer 4
You can change the emitting color by changing the J9 sill.
11 functions, and two constituent materials, namely semiconductors? It is possible to emit all the neutral colors of the characteristic light emission of the semiconductor material with the larger forbidden band width used for the 1v film layers 3 and 5 and the semiconductor material with the smaller Nj bandgap width used for the active layer 4. .

That is, as described above, as shown in Figure 1)2 (A), 21' conductors with different forbidden band widths, such as ZnS and Z
When nSe is formed into a Jt'L layer, a quantum well QW is formed as shown in FIG. As shown in Figure 2 (B), in a flat well that has a well in one direction and the remaining two-dimensional directions are free, =1.2.3.19 and 1):ru. Here, L1 is prohibited - "F small width"1' wall layer No.
The numbers Kx and Ky are the X and y components of the wave number vector.

Let's turn it around, li'fl-i゛J111
The energy Eh of one hole in the QW is as follows: (2) n'=1.2.3.1-.

In addition, in 1-(J,) and equation (2), i: h/'2π
where h is a blank constant, me and mh are electrons, and 11 is the effective charge of the hole.

Kx, Ky are O<Kx, Ky, (Kx', Ky')<
Since it takes the value of (Kx, Ky, Kx', Ky'~0
, n, n' = 1), the minimum energy that an electron can take in the conduction band is f12 (π/L)2/2me, and the minimum energy that a '+F hole can take in the valence band is ++2 (
g/L) 2/2mh, which is practically prohibited at 91? Width E
g is 'T12 π E g = E g CZn5e) + -() 2m
eL h2,? +′ +−−(−)2 mhT−. Therefore, by changing L, one! 1-The band width Eg can be changed within the range of Eg (ZnSe)<Eg<Eg (ZnS).

Therefore, by changing the width of the Zn5e layer in the -11 example (laminated body of ZnSe and ZnS), the transmission i of a 1'-conductor with a small forbidden band width (7.n S e in this case) can be improved.
From the Q band-valence electron-interband light wavelength (4640 people), a large 1' conductor (this JJi', combined with Z
n5) conduction i1) - wavelength of emission between valence band (339
The luminescent colors range from 0 to 11.

The combination of conductor materials used in the laminate in the conductor thin film photonic element of the present invention may be any combination as long as the material differs in the forbidden band width. 9 that influences the performance of heterojunction devices.
) The case r mismatch in the amount of material φ that becomes P is as large as in other heterojunction devices because each layer is extremely thin in the laminate of the present invention. No impact will occur. Therefore, it is applicable not only to the combinations conventionally used for Peter junctions, but also to a wider range of 181t combinations. For example, ZnS-
Zn5e silk combination, green luminescence fII G
aA1. P-GaP combination, red light emission is fJ
Examples include the combination of GaP-GaAsP, which can emit infrared light, and the combination of GaA and LAs-GaAs, which can emit infrared light.
Combinations of 3-binary and 4-binary compounds are also possible, and the scope of their application is extremely wide.In the attached table, some semiconductor combinations are shown in terms of quadratic band width, lattice constant, and interband emission wavelength. ]((This is shown.

Further, each y-conductor layer 3.4.5 may be manufactured by an appropriate method, such as a vacuum method such as a laser beam method or a resistance heating method. hot laol epitaxial method (
RWE), molecular beam epitaxial method (MBE),
C'V D7,14, MOCVD method, Ij;

FIG. 4 shows the present invention ``1'', conductor t'! This shows the collapse of the second "p" of the j tlζ1 luminescent element r-.

In this embodiment, the 16-layer body 7a is
Layer 3.3 (, Ji'i
thick 100~101) OA) is arranged; [vl insert, f(
1) Between B-co, IF, heavy belt 'llll1! 17) The smaller 1'19 body layer (1'1'': 10 to 20 people), that is, the active layer 4, and the l'H and rx body layers 5o'i of the large force band width 50 to 500 people) or stacked on top of the father I
J12.

With this multi-layer structure, more intense light emission (i+1) can be achieved.

Figure 5 shows 144 bodies of the present invention. This is the second (extremely small variation) of the light-emitting element.

In this modification, the active layer 4 of the laminate 7b has a thickness of 410 layers located on the transparent electrode 2 side, and the back electrode 6
The layer thickness of the layer 40 located on the side is increased, and the fact that the layer J of the active layer 4 is thicker as the back surface 'f [ is closer to the pole 6] is defined as 'l'l-characteristic.

With this configuration, where the active layer 11 is thin, the prohibition of "-41?" is effectively achieved. Width Eg expands
(Eg (1)>Eg (2) ・Conflict・>E4(n
)), emission of shorter wavelength can be obtained. Therefore, the emitted light color in each active layer 41.42.43...4n is different, and in this device, each of these active layers 41.4n
2. What is the light emission due to the composite color of the light emission color of 43,...4n?
4.1. In the case of this modification, there is a center gap that allows light to be emitted with a longer wavelength as the distance from the transparent electrode 2 increases, and therefore, the layer thickness of the active layer 4 needs to be increased as it is closer to the back electrode 6. Kaa・ru.

In the case of J1 shown in FIGS. 4 and 5, it goes without saying that an impurity is added to the semiconductor thin film layer 3.5 to form an energy IQ- level in the middle of the forbidden band of the material semiconductor.

[Brief explanation of the drawing]

Figure 1 shows the first performance 1p of the semiconductor thin film light emitting device r- of the present invention.
A schematic side view showing an example, FIG. 2 is the present invention 1', 4 bodies f:
VI Each layer of the laminate in the simulated light emitting element r and energy 1
(+4th place 1' (shows the relationship with the i state, (A) is a cross-sectional view showing the laminate sliced thinly in the thickness direction, CB)
is a diagram showing the distribution of energy -Q+3 in each layer as well as 't' for (A), and FIG.
・IIQ light emission, energy 7 to explain the action of F'r (1st division Figure 11, Figure 4 is the present invention
'The second embodiment of the thin conductor light-emitting element r- is shaped like a plug...
FIG. 7 is a schematic side view of the example. 1. Explanation 2...◆Transparent゛11. ξ Pole, 3... The 1' mind body of the infinitely friendly power: i, j, + II, 4...
Active+1 layer, 5...4; (Larger side band 1' conductor thin film, 6...Back 'IU, J4j,
7.7a, ';'l)'' ``Laminated body diagram, Figure 4 = Figure 2), Figure 3, Figure 4, Figure 4, Figure 5, etc.

Claims (1)

[Claims] (,1)Using 15 system (j;・2 types of 1' with different widths) 9 thin llI','1 layers, l-light-emitting element, l! (11) A conductor thin film layer with a small width and a small force is used as an active layer, and ii'f is laminated on a 11 layer sandwiched between +5' and 1' layers with a large width. , 5q'l)
1. The larger one of 1.1 and 1. The conductor thin film layer is
No rest, '1. There is an energy Ql between I+, ;ii;
i 4S/N/f impurities are added to emit light from a thin conductor (1').