CN102779846A - Dual-heterojunction bipolar transistor structure - Google Patents

Abstract

The present invention provides a double heterojunction bipolar transistor structure, which sequentially includes: a collector layer composed of a compound containing phosphorus and indium, a base layer, and an emitter layer composed of a compound semiconductor containing phosphorus and indium, Wherein, the material of the base layer includes a variety of compounds composed of indium, gallium, arsenic and antimony, and the indium, gallium, arsenic and antimony components contained in each compound are different from the indium contained in other compounds. , gallium, arsenic and antimony are different, and the composition ratio of indium to gallium in each compound is :(1- ), the composition ratio of arsenic to antimony is

:(1-

), and the energy band structure of the base layer is narrowed from the emitter junction to the collector junction, wherein,

,

. The double heterojunction bipolar transistor structure can reduce the conduction band barrier of the emitter junction and alleviate the problem of blocking electron injection, and at the same time form a built-in potential difference from the emitter junction to the collector junction in the base region, effectively reducing the flow of electrons in the base region. The transit time is beneficial to improve the frequency characteristics of the device.

Description

The double hetero bipolar transistor structure

Technical field

The invention belongs to microelectronic, particularly a kind of double hetero bipolar transistor structure.

Background technology

Heterojunction bipolar transistor (HBT) be a kind of be on the silica-based bipolar transistor of tradition basis, in conjunction with heterojunction and energy band engineering theoretical developments and a kind of ambipolar electronic device that comes.The HBT biggest advantage is to have remarkable high frequency and high speed characteristics; Obtained using widely in many important national security such as radio communication, optical fiber communication and remote sensing and people's economic life field by Primary Component such as its amplifier that constitutes as the core active device, frequency mixer and voltage controlled oscillator or module; Waiting some specific areas also to occupy indispensable critical role such as personal radio communication terminal (chip for cell phone); Can predict; Further developing and using, bigger effects more than HBT and correlation module thereof and circuit will be brought into play more along with high-speed communication of future generation, broadband wireless sensing net, meticulous imaging and detection, novel satellite navigation and navigation system and radio-frequency recognition system.

The high-frequency high-speed characteristic of HBT device has benefited from its unique band structure on the one hand, is owing to select to have adopted the compound semiconductor that has than high electron mobility and electron saturation velocities as the device architecture material on the other hand.Particularly the advantageous characteristic that has of InP system material makes InP base HBT device possess lot of advantages.The combination property of the InP/GaAsSb/InPDHBT of employing II type band structure is the most potential at present, has research to show that it will become the first-selection of Terahertz transistor technology.

For InP/GaAsSb/InP DHBT, still exist two subject matters to influence and restricted the further raising of its device performance at present.First problem is that the II type of InP/GaAsSb/InP can be with arrangement architecture; Though efficiently solve the current blocking effect of base-collector region heterojunction; But simultaneously in the emitter region-heterojunction place in base also exists and hinders electronics and can be with potential barrier from the emitter region to the conduction band that the base injects; The existence of this potential barrier has caused the accumulation of electronics at emitter junction potential barrier place, be unfavorable for electronics from the emitter region transporting to the base.The another one problem then is, in very thin thickness and in the highly doped GaAsSb base, lower electrons spread speed has caused bigger Base Transit Time, has restricted the further raising of its high frequency performance.

Summary of the invention

The object of the present invention is to provide the little double hetero bipolar transistor structure of a kind of Base Transit Time, to improve the frequency characteristic of device.

Reach other purposes in order to achieve the above object; Double hetero bipolar transistor structure provided by the invention; It comprises in regular turn: comprise collector layer, the base layer that the compound of phosphorus and indium constitutes and comprise phosphorus and the emitter layer of the compound semiconductor of indium formation; Wherein, The material of said base layer comprises the multiple compound of all being made up of indium, gallium, arsenic and antimony, and indium, gallium, arsenic and antimony that each compound indium, gallium, arsenic and the antimony component that comprise and other kinds compound are comprised are all inequality, and in each compound the component of component and the gallium of indium than being x: (1-x); The component of arsenic is y with the component of antimony ratio: (1-y); And the band structure of said base layer is narrowed down by wide to the collector junction place from emitter junction, wherein, and

As a kind of optimal way, said base layer comprises multilayer, and the material of each layer is a kind of in the said multiple compound.As another optimal way, said base layer is an individual layer, and the distribution of said multiple compound in said individual layer makes the component of indium, gallium, arsenic and antimony be linear taper from emitter junction to the collector junction place.

In sum; The base layer of double hetero bipolar transistor structure adopts band alternation of the present invention; Thus can be when reducing the emitter junction conduction band barrier, alleviating block electrons injection problem; The base form from the emitter junction to the collector junction in build electrical potential difference, effectively reduce the transit time of electronics in the base, help improving the frequency characteristic of device.

Description of drawings

Fig. 1 is the preferred embodiment sketch map of double hetero bipolar transistor structure of the present invention;

A kind of optimal way sketch map of the base layer that Fig. 2 comprises for double hetero bipolar transistor structure of the present invention;

The another kind of optimal way sketch map of the base layer that Fig. 3 comprises for double hetero bipolar transistor structure of the present invention;

Fig. 4 is for adopting the band structure sketch map of the formed double hetero bipolar transistor structure of base layer shown in Figure 2;

Fig. 5 is for adopting the band structure sketch map of the formed double hetero bipolar transistor structure of base layer shown in Figure 3.

Embodiment

Below will specify double hetero bipolar transistor structure of the present invention with a preferred embodiment.

See also Fig. 1, double hetero bipolar transistor structure of the present invention comprises successively: InP substrate 101, InP resilient coating 102, collector region ohmic contact layer 103, collector layer 104, base layer 105, emitter layer 106 and emitter region ohmic contact layer 107.

Said InP resilient coating 102 can adopt epitaxial growth method to be formed on the said InP substrate 101.Preferable, said InP resilient coating 102 is the layer that undopes.

Said collector region ohmic contact layer 103 is on InP resilient coating 102.As a kind of preferred, said collector region ohmic contact layer 103 can be N type InGaAs heavily doped layer, for example, adopts silicon (Si) as dopant, and doping content is about 10 ¹⁹Cm ^-3Deng.

Said collector layer 104 also can adopt epitaxial growth to form on said collector region ohmic contact layer 103.As a kind of preferred, said collector layer 104 can be N type InP low doped layer, for example, adopts silicon (Si) as dopant, and doping content is about 10 ¹⁶Cm ^-3Deng.

Said base layer 105 is on said collector layer 104, and it can adopt molecular beam epitaxy system or formed by the metal organic vapor deposition growing.The material of said base layer comprises the multiple compound of all being made up of indium, gallium, arsenic and antimony; And indium, gallium, arsenic and antimony that the indium that each compound comprises, gallium, arsenic and antimony component and other kinds compound are comprised are all inequality; And the component of indium is x with the component ratio of gallium in each compound: (1-x); The component of arsenic is y with the component of antimony ratio: (1-y); And the band structure of said base layer is narrowed down by wide to the collector junction place from emitter junction; Wherein,

As a kind of preferred version, said base layer 105 can comprise multilayer, and the material of each layer is a kind of in the said multiple compound.Preferable, each In _xGa _1-xAs _ySb _1-yCompound layer can also mix, and for example, as dopant, its doping content can be 10 with carbon ¹⁹Cm ^-3-10 ²⁰Cm ^-3

As shown in Figure 2, said base layer 105a comprises the In of three layers of different materials component (being that x is different with the y value) _xGa _1-xAs _ySb _1-yCompound layer is folded mutually to be formed, and says it more in detail, and it comprises:

Be positioned at the In that links to each other with collector region _X1Ga _1-x1As _Y1Sb _1-y1 Ground floor 1051;

At In _X1Ga _1-x1As _Y1Sb _1-y1In above the ground floor 201 _X2Ga _1-x2As _Y2Sb _1-y2The second layer 1052;

At In _X2Ga _1-x2As _Y2Sb _1-y2In above the second layer 202 _X3Ga _1-x3As _Y3Sb _1-y3The 3rd layer 1053; Wherein, the In of three layers of different component _xGa _1-xAs _ySb _1-yMaterial; Be the material with InP backing material lattice match, its value can be calculated through empirical equation and tentatively draw, and confirms through the test of high-resolution X-ray diffraction; In order to realize stepped can the arrangement by band, satisfy the condition of x1＞x2＞x3, y1＞y2＞y3 simultaneously.

As another kind of preferred version, said base layer 105 is an individual layer, and the distribution of said multiple compound in said individual layer makes the component of indium, gallium, arsenic and antimony be linear taper from emitter junction to the collector junction place.Preferable, said base layer 105 can also mix, and for example, as dopant, its doping content can be 10 with carbon ¹⁹Cm ^-3-10 ²⁰Cm ^-3

As shown in Figure 3, the x of the material of said base layer 105b, y value spontaneous emission area edge are in the In at two ends to collector region edge linear taper successively _xGa _1-xAs _ySb _1-yMaterial is respectively and InP backing material lattice matched materials, and its value can be calculated through empirical equation and tentatively draw, and confirms through the test of high-resolution X-ray diffraction.

Said emitter layer 106 can adopt epitaxial growth to form on base layer 105.As a kind of preferred, said emitter layer 106 can comprise the N type InP layer of doping, for example, and doping content about 10 ¹⁷Cm ^-3Si etc.

Said emitter region ohmic contact layer 107 can adopt epitaxial growth to form on said emitter layer 106.As a kind of preferred, said emitter region ohmic contact layer 107 can comprise N type InGaAs heavily doped layer, for example, adopts silicon (Si) as dopant, and doping content is about 10 ¹⁹Cm ^-3Deng.

Above-mentioned described double hetero bipolar transistor structure; If adopt base layer 105a shown in Figure 2; The band structure sketch map of then formed double hetero bipolar transistor structure is as shown in Figure 4, and this band structure comprises: the ability zone 303 that is three stair-stepping ability zones 302, InP collector region 104 correspondences that ability zone 301, the base layer 105a of InP emitter layer 106 correspondences is corresponding; If adopt base layer 105b shown in Figure 3; The band structure sketch map of formed double hetero bipolar transistor structure is as shown in Figure 5, and this band structure comprises: the ability zone 502 that is the linear taper shape that ability zone 501, the base layer 105b of InP emitter layer 106 correspondences is corresponding, the ability zone 503 of InP collector region 104 correspondences.

In sum, the beneficial effect of double hetero bipolar transistor structure of the present invention is:

(1) in the II type that has kept conventional InP/GaAsSb/InP can be with arrangement architecture, do not exist in the advantage of current blocking effect of base-collector region heterojunction; The InP/InGaAsSb dissimilar materials structure that the employing InGaAsSb material lower than GaAsSb material conduction band forms; Also can effectively eliminate in emitter region-base the heterogeneous obstruction electronics that exists of bearing also and can be with the caused electronics of potential barrier to stop problem, more help electronics injection to the base from the emitter region from the emitter region to the conduction band that the base injects.

(2) can solve in very thin thickness and in the highly doped GaAsSb base lower electrons spread speed caused bigger Base Transit Time and the problem of the device high frequency performance restriction that causes.That adopts that the base structure of alternation forms alternation can be with arrangement architecture; Produce quasi-electric field in the base, the The built-in electrical potential difference helps the electron drift transmission of base, has reduced the transit time of electronics in the base; Thereby also reduced electronics simultaneously and reduced base recombination in the time of staying of base; In addition, can also make to be injected into the higher first kinetic energy of collector region electronics acquisition, further reduce the transit time of collector region.

(3) adopted carbon as impurity in the base layer, because carbon is as In _xGa _1-xAs _ySb _1-yThe P type dopant of material has the very high doping limit, generally can reach 10 ²⁰Cm ^-3, impurity is more stable simultaneously, the difficult diffusion.Therefore; Compare as the conventional DHBT structure of P type heavily doped layer with employing beryllium (Be); P type heavily doped layer can obtain higher doping content in the material layer of this new device structure; Can also avoid simultaneously impurity to the layer diffusion that undope of I type, thereby make its device can obtain lower base resistance, and not influence the electrical characteristics of other layers.

The foregoing description is just listed expressivity principle of the present invention and effect is described, but not is used to limit the present invention.Any personnel that are familiar with this technology all can make amendment to the foregoing description under spirit of the present invention and scope.Therefore, rights protection scope of the present invention should be listed like claims.

Claims (7)

1. double hetero bipolar transistor structure, it comprises in regular turn: comprise collector layer, the base layer that the compound of phosphorus and indium constitutes and comprise phosphorus and the emitter layer of the compound semiconductor of indium formation, it is characterized in that:

The material of said base layer comprises the multiple compound of all being made up of indium, gallium, arsenic and antimony; And indium, gallium, arsenic and antimony that the indium that each compound comprises, gallium, arsenic and antimony component and other kinds compound are comprised are all inequality; And the component of indium is x with the component ratio of gallium in each compound: (1-x), the component of arsenic is y with the component of antimony ratio: (1-y), and the band structure of said base layer is narrowed down by wide from emitter junction to the collector junction place; Wherein $x\⋐\left(\mathrm{0,1}\right),y\⋐\left(\mathrm{0,1}\right).$

2. double hetero bipolar transistor structure as claimed in claim 1 is characterized in that: said base layer comprises multilayer, and the material of each layer is a kind of in the said multiple compound.

3. double hetero bipolar transistor structure as claimed in claim 1 is characterized in that: said base layer is an individual layer, and the distribution of said multiple compound in said individual layer makes the component of indium, gallium, arsenic and antimony be linear taper from emitter junction to the collector junction place.

4. like claim 2 or 3 described double hetero bipolar transistor structures, it is characterized in that: said base layer is a heavily doped layer.

5. double hetero bipolar transistor structure as claimed in claim 4 is characterized in that: said base layer is with the heavily doped layer of carbon as dopant.

6. double hetero bipolar transistor structure as claimed in claim 4 is characterized in that: the doping content in the said base layer is 10 ¹⁹Cm ^-3-10 ²⁰Cm ^-3

7. like claim 2 or 3 described double hetero bipolar transistor structures, it is characterized in that: said base layer is perhaps formed by the metal organic vapor deposition growing by molecular beam epitaxy system.

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