JPH0193166A - semiconductor equipment - Google Patents

Abstract

PURPOSE:To reduce base resistance of a resonance tunneling hot electron transistor by a method wherein a resonance tunneling barrier is constituted of a first quantum well barrier layer, a first quantum well layer, and a second quantum well barrier layer. CONSTITUTION:An N<+>-GaAs collector layer 1 is grown on a semi-insulating GaAs substrate SI. A non-dope GaAs layer is grown 1500Angstrom thick, Be is planar- doped thereinto, and then another non-dope GaAs layer is grown 500Angstrom thick, for the formation of a collector barrier 2. An N<+> GaAs base layer 3 is grown, and then quantum well layers 4, 5, and 6 are formed. Here, the GaAs barrier layers 4 and 6 are 100Angstrom thick each and planar-doped with Be at a level half the thickness, and the non-dope layer 5 is a 100Angstrom -thick well layer. Finally, an N<+>-GaAs emitter layer 7 is grown for the completion of an epitaxial layer structure. This design reduces the resistance a base may present in a resonance tunneling hot transistor.

Description

[Detailed Description of the Invention] [Summary] When a semiconductor is doped with a large amount of impurities, the band structure is affected. 2 called planar doping (PD)
A quantum well was formed as an emitter barrier and one potential barrier was formed as a collector barrier using a semiconductor method (MBE method) by dimensional local doping.

The RHET of the present invention has a multilayer structure made only of GaAs without using AlGaAs, so that good device characteristics can be obtained and the manufacturing process can be simplified.

[Industrial application field]

The present invention relates to resonant tunneling hot electron transistor (RHET) structures.

RHET is a new device recently created by applying a superlattice structure. This device utilizes the resonant tunneling effect and can control the movement of high-energy hot electrons, allowing it to have functions such as high-speed logic and memory.

Furthermore, it is expected that a circuit device constituting an LSI can be realized using a minimum number of devices.

RHET is currently still in the research and development stage, and research on crystal materials and element structure 5 circuit design is actively progressing (Conventional technology) RHET has conventionally always had a compound semiconductor heterojunction;
GaAs/AlGaAs, GaAs/AlGaAs
are examples. FIG. 3 shows the structure of a conventional RHET. In this example, semi-insulating Ga
For example, 2MbE on an As substrate (S, 1.GaAs)
The n”-GaAs collector layer 11.AlG
aAs barrier layer 12. An n-GaAs base layer 13 is formed, and an AlGaAs layer 14°GaAsW! i 15+
A quantum well layer of AlGaAs layer 16 and an n'' GaAs emitter layer 17 are formed.

For example, the specifications of each layer are as follows.

Drawing number Epitaxial concentration Thickness layer,
(Cm””) (person) 11
n+ -GaA's 5xl
O” 300012 Alx Ga1-xA
s (x=0.2) Non-doped 200013
n"-GaAs 1xlO" 50
014 AlxGa, -xAs (x=0.3) Non-doped 5015 GaAs Non-doped 5016 AlGaAs■As (x=0.
3) Non-doped 5017 n”-Ga
As 5xlO" 20001 Part 50 Emitter 17. Base 13. Collector 11 Gold/germanium/gold (AuGe/Au) electrodes are attached to each layer.

[Problem that the invention seeks to solve]

As is clear from the conventional example, RHET is made of GaAs and A
It is composed of a heterojunction with lGaAs. Therefore, device processes and epitaxial growth processes generally have to be more complicated than processes that do not include a heterojunction and are made only of GaAs, for example.

[Means for solving problems]

These problems can be solved by using a collector layer made of n-type gallium arsenide (GaAs) and beryllium (B) on a semi-insulating substrate.
e) is a collector barrier layer made of planar-doped gallium arsenide, a base layer made of n-type gallium arsenide, a first quantum well barrier layer made of gallium arsenide planar-doped with beryllium, and a quantum well well layer made of gallium arsenide. , a second quantum well barrier layer made of gallium arsenide planar-doped with beryllium, and an emitter layer made of n-type gallium arsenide are formed, and the first quantum well barrier layer, the quantum well well layer, and the second quantum well are formed. R) characterized in that the barrier layer has a resonance/tunneling barrier configuration (solved by ET).

[Effect]

FIG. 2 is a band structure diagram of the planar-doped RHET according to the present invention, particularly showing the conduction band bottom (Ec).

What is called planar doping temporarily halts epitaxial growth in the MBE method.

This is a method in which only the dopant is supplied in this state and then growth starts again. Taking the case of GaAsMBE as an example, if the supply of Ga beam is interrupted, the growth is interrupted.
Silicon (S) is used as an n-type dopant in an S atmosphere.
i) Beryllium (Be) is supplied as the p-type dopant. Then growth resumes.

In planar doping of GaAs, the dopant diffusion is suppressed to within 40%, and the 9-plane concentration is up to 5xlOl2c.
m"" is possible.

n-type GaAs? , :Be planar doping produces a protrusion of about 0.4 eV at the conduction band bottom (Ec), which becomes a potential barrier. By forming a quantum well with two barriers in the emitter, the first resonance level (E,) can be set to about 0.2 eV. If we form one barrier in the collector and one quantum well in the emitter in this way,
A planar doped RHET structure is completed.

A major improvement in device characteristics in the present invention is a reduction in base resistance. In the conventional example, as shown in FIG. 3, the base electrode has resonant tunneling barriers 14, 15 . n on i6
A type GaAs layer 17 is formed on this, leaving about 50 layers. According to the experimental results, gold/germanium/gold (200
A metal film with a thickness of 30 people/2800 people is made of non-doped AlGaAs with a thickness of 30 people, and a non-doped G film with a thickness of 30 people
When deposited on aAs and heat treated at 450°C for 1 minute, the contact resistivity of the former is approximately 2.0x10
-5ΩC1112, the latter is 2.0xlO-'Ωc
It is ffI2. As can be seen from this result, GaAs
The base resistance of the R HE T according to the present invention, which is constructed solely by the present invention, is reduced by one order of magnitude compared to the conventional example.

〔Example〕

FIG. 1 is a schematic cross-sectional structural diagram of a planar-doped RHET according to the present invention.

MB on a semi-insulating GaAs substrate (5,1,GaAs)
First, an n''-GaAs collector layer 1 was grown using the E method.

Next, after making only 1500 non-doped GaAsN, Be was doped planarly and non-doped GaAs was added again.
A collector barrier layer 2 is formed by growing 500 layers of s. Next, the n''-GaAs base layer 3 is grown to form the post-quantum well layers 4, 5.6. That is, the GaAs barrier layer 4
．． No. 6 has a thickness of 100 μm and is doped with Be planar at half the thickness. Non-doped Ga
The As layer 5 is a well layer with a thickness of 100 .mu.m.

Finally, an n''-GaAs emitter layer 7 is grown to complete the epitaxial layer structure.

In the figure, the position of the planar doped surface is indicated by a dotted line.

Emitter layer 7. Base N3. Collector layer 1 includes gold/germanium (200 people) / gold (3000 people) (
The main specifications of each of the above-mentioned AuGe epitaxial layers are summarized below.

Drawing number Epitaxial concentration Thickness Ji
(cm-') (person) 1 n''-
GaAs 5xlO” 30002
GaAs non-doped 1500PD:Be
1xlO"cm-2 GaAs Non-doped 500 3 n" -GaAs 1xlO"
5004 GaAs non-doped
50PD ; Be 1xlOl2cm-2GaAs
Non-doped 50 5 GaAs Non-doped 1005
GaAs non-doped 50PD
2Be 1xlO"cm-2GaAs Non-doped 50 [Effects of the Invention] Conventional RHE T always includes a hemijunction of a compound semiconductor. For this reason, the epitaxial growth process and device process process in manufacturing the element become complicated. I don't get it.

Since the RHET according to the present invention does not utilize any heterojunctions and is composed of only homojunctions, the conventional device manufacturing process is simplified, which greatly contributes to lowering the cost of the device.

Furthermore, the base resistance of the element was reduced to one-tenth of that of the conventional RHET in the RHET of the present invention, which does not contain any /1I GaAs. This is an advance in the development of RHET as a high speed device.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional structural diagram of a planar-doped RHE i' according to the present invention. FIG. 2 is an energy band structure diagram of a planar-doped RHET according to the present invention. FIG. 3 is a schematic cross-sectional structural diagram of a conventional RHET. In fig. 1 is an n''-GaAs collector layer. 2 is a GaAs collector barrier layer. 3 is an n''-GaAs base layer. 4.5.6 is a GaAs quantum well layer. 7 is an n''-GaAs emitter layer. Patent applicant: Director of the Agency of Industrial Science and Technology Kozo Iizuka 1 N6aAs layer 7ii 2 (mAs: IL layer 7 layer 3 N6
aA5 , (-7厘4 qaAs Signed to complete; Su? Eyebrow 5 Gra
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I) tFp+r'J? Eyebrow 7 lσ' (raA5 Engineering, Mi, Rita Kakusui Suishi Issaku 10th page R1-11m section structure by Yusaku Moto, Yuta・Hako No. 1
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Claims (1)

[Claims] A collector layer made of n-type gallium arsenide (GaAs) on a semi-insulating substrate, a collector barrier layer made of gallium arsenide planar-doped with beryllium (Be), a base layer made of n-type gallium arsenide, and a beryllium-doped base layer. A first quantum well barrier layer made of gallium arsenide, a quantum well well layer made of gallium arsenide, a second quantum well barrier layer made of gallium arsenide planar-doped with beryllium, and an emitter layer made of n-type gallium arsenide are formed. . A semiconductor device, wherein the first quantum well barrier layer, the quantum well well layer, and the second quantum well barrier layer have a resonant tunneling barrier configuration.