JPH11297711A - Manufacture of semiconductor wafer and epitaxial wafer for heterobipolar transistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the interrupt of growth between a base and an emitter for temperature rise, when having an emitter layer grown following the growth of the base layer of an epitaxial wafer for an HBT(heterobipolar transistor). SOLUTION: In this manufacturing method, an organometallic vapor phase epitaxy(MOVPE) method or a gas source molecular beam epitaxial growth(MBE) method is used and an n-type collector contact layer 2, an n-type collector layer 3, a p-type GaAs base layer 4, an n-type AlGaAs emitter layer 5 and an n-type emitter contact layer 6 are made to grow successively. In this case, at the epitaxial growing of the AlGaAs emitter layer 5, triethylgallium(TEG) is used as a gallium(Ga) source, and the growth temperature of the emitter layer 5 is made identical to the growing temperature of the base layer 4 in the temperature range of 500 deg.C-550 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor wafer and an epitaxial wafer for a hetero-bipolar transistor (HBT) manufactured by using the method, and more particularly to an A-type epitaxial wafer.
The present invention relates to improvement of current amplification factor β of 1GaAs / GaAs HBT.

[0002]

2. Description of the Related Art A hetero-junction bipolar transistor (HBT) using a hetero-junction for an emitter-base junction is known.
When the band gap of the emitter layer is wider than the band gap of the base layer, the porosity of the emitter can be increased. Therefore, it is expected to be used as an ultra-high-speed and high-output device. In particular, HBTs made of AlGaAs / GaAs are excellent in high-speed operation and high-current driving capability, and are therefore being actively developed as high-speed electronic devices for optical communication.

The compound semiconductor layer constituting the GaAs / AlGaAs-based HBT is mainly grown by an epitaxial growth method. As a method of epitaxially growing a compound semiconductor such as GaAs, a metal organic chemical vapor deposition (MOVPE) method is currently generally used. That is, when GaAs, AlGaAs or the like is subjected to metal organic chemical vapor deposition, trimethyl gallium (TMG) is used as a Ga source, trimethyl aluminum (TMAl) is used as an Al source, and arsine (AsH ₃ ) is used as an As source. ) To a growth temperature of 600 ° C. to 700 ° C.
℃ to grow.

Incidentally, the epitaxial wafer for HBT requires a high-concentration p-type GaAs base layer, and a high-steep pn junction before and after the layer. Therefore, it is necessary to dope the GaAs layer with a p-type dopant at a high concentration. Conventionally, zinc (Zn), beryllium (Be), and magnesium (Mg) have been used as p-type dopants for doping the GaAs layer.

Recently, GaAs / AlGaAs based HB
At T, with the development of epitaxial growth technology, G
High impurity concentration (maximum 1 ×) instead of zinc or beryllium, which has been conventionally used as the p-type impurity of the aAs layer,
( ^{Approximately} 10 ²⁰ cm ⁻³ ), and ideal carbon has been used as a p-type impurity having a very small diffusion constant. The carbon source is carbon tetrabromide (CBr).
₄ ) There are halogenated carbons. However, this CBr ₄
In the case where GaAs is used as a carbon source, if the growth temperature of the GaAs crystal is high, the doping efficiency deteriorates.
It is difficult to obtain an impurity concentration of the order of ¹⁹ cm ⁻³ or less, and the etching action is caused by the halogen group of the halogenated carbon, and the surface of the epitaxial wafer is fogged. Therefore, GaAs that satisfies good surface and crystallinity
In order to obtain a base layer, it was necessary to lower the growth temperature of the GaAs base layer.

On the other hand, TMG and TMAl have conventionally been used as Group III raw materials for the growth of the AlGaAs crystal of the emitter layer. When the growth temperature of the AlGaAs is lowered along with the lowering of the growth temperature of the base layer, the TMAl Oxygen or carbon contained in the raw material itself penetrates into the crystal, and the donor is compensated by a deep energy order or a carbon acceptor, thereby deteriorating the quality of the crystal and increasing the current amplification factor β of the HBT.
And the life of the element is shortened. Also, when the growth temperature is lowered, the growth mode is switched from the raw material rate control mode to the supply rate control mode, and the uniformity of the film thickness is deteriorated. This is an important problem because it directly affects the yield of device fabrication.

Therefore, as shown in the left column of FIG. 1, in the conventional method of manufacturing a semiconductor wafer, the growth temperature (for example, 520 ° C.) is lower than the growth temperature (600 ° C. to 700 ° C.) normally used for growing an epitaxial wafer for a high-frequency device. ) Grows the base layer. Therefore, since the growth temperature of AlGaAs serving as the emitter layer is 600 ° C. to 700 ° C., after the base layer is grown, the growth is interrupted when the emitter layer is grown, and after the semiconductor growth apparatus is heated, the emitter layer is cooled. Growing.

[0008]

As described above, in the prior art, in order to improve the quality of the emitter layer made of AlGaAs crystal, the growth temperature must be increased between the growth of the base layer and the growth of the emitter layer. We had to put in a growth break to change.

However, due to the interruption of the growth, a defect due to thermal damage enters the interface between the base and the emitter layer, and the base current flows to the emitter side via the defect, thereby reducing the current amplification factor β and the life. I knew it. Therefore, in order to solve this problem, a manufacturing technique capable of eliminating the interruption of the growth between the base and the emitter or shortening the growth interruption time while maintaining the AlGaAs crystallinity of the emitter layer equivalent to that of the conventional method. Provision is desired.

An object of the present invention is to solve the above-mentioned problems in a method of manufacturing a semiconductor wafer in which a base layer and an emitter layer are grown by MOVPE or gas source MBE (Molecular Beam Epitaxial Growth). While maintaining the same AlGaAs crystallinity as the base,
An object of the present invention is to provide a method of manufacturing a semiconductor wafer capable of eliminating the interruption of the growth between the emitters or shortening the interruption time of the growth, and an epitaxial wafer for HBT manufactured by the method.

[0011]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as follows.

According to the first aspect of the present invention, a collector contact layer exhibiting n-type conduction, a collector layer exhibiting n-type conduction,
a base layer made of GaAs (gallium arsenide) crystal showing p-type conductivity, an emitter layer made of AlGaAs (aluminum gallium arsenide) crystal showing n-type conductivity forming a heterojunction with the base layer, and n In the method of manufacturing a semiconductor wafer in which an emitter contact layer exhibiting a negative conduction is sequentially grown, triethylgallium (TEG) is used as a gallium (Ga) source, and the growth temperature of the emitter layer is controlled by a base layer during epitaxial growth of the emitter layer. At a growth temperature of 550 ° C. or higher. In the epitaxial growth of the emitter layer, trimethyl aluminum (TM) is used as an aluminum (Al) source.
Al) can be used (claim 2).

[0013] With such a structure, a defect due to thermal damage due to the conventional interruption of the growth is not generated at the interface between the base and the emitter layer, and AlGaAs equivalent to the conventional method is formed.
An AlGaAs emitter layer exhibiting crystallinity can be grown. Therefore, according to the manufacturing method of the present invention, a semiconductor wafer having a high current amplification factor β and a long life can be obtained while eliminating the conventional interruption of the growth between the base and the emitter or shortening the interruption time of the growth.

In the present invention, the epitaxial growth temperature of the emitter layer is specifically set at 500 ° C. to 550 ° C. (claim 3). The reason why the growth temperature of the AlGaAs emitter layer is limited to 500 ° C. to 550 ° C. is as follows. That is, as a result of repeating the test by the present inventors, in the case of a GaAs crystal using TEG and arsine as the raw materials, the temperature range in which the growth of the raw materials with good uniformity in film thickness is controlled is approximately 400 ° C. to 550 ° C. Was. On the other hand, TM
In the case of an AlAs crystal using Al and arsine, the lower limit of the temperature range in which the material is transported with good film thickness uniformity and the rate is controlled is surprisingly about 500 ° C., which is lower than the conventionally considered about 550 ° C. I found it. From both, AlGaAs using TEG, TMAl and arsine
This is because, in the case of a crystal, the temperature range in which the crystal is grown at a rate of controlling the raw material transport with good uniformity of the film thickness is 500 ° C. to 550 ° C.

In the present invention, it is advantageous to use triethylgallium (TEG) as the gallium (Ga) source in epitaxial growth of the base layer because the same material as in the growth of the emitter layer is used. .
In the epitaxial growth of the base layer, carbon tetrabromide (CBr ₄ ) can be used as a p-type dopant.

In the manufacturing method of the present invention, the most preferable mode is one in which the epitaxial growth temperatures of the base layer and the emitter layer are matched. This is because the next emitter layer can be grown without interrupting the temperature rise after the growth of the base layer.

In the manufacturing method of the present invention, an undoped GaAs spacer layer having a thickness of 1 to 8 nm may be grown between the base layer and the emitter layer. By providing such a spacer layer, entry of carbon, which is a p-type dopant, into the emitter layer can be suppressed, and a shift between the hetero interface and the pn interface can be eliminated to some extent. The reason why the thickness of the undoped GaAs spacer layer is numerically limited to 1 to 8 nm in the invention of claim 7 is as follows. That is, if the spacer layer is not inserted with a thickness of 1 nm or more, the effect of suppressing the entry of carbon, which is a p-type dopant, into the emitter layer and eliminating the shift between the hetero interface and the pn interface has no effect. If the thickness of the spacer layer is too large to exceed 8 nm, it becomes a barrier to electrons injected from the emitter layer to the base layer.
This is because the collector current decreases and the current amplification factor β decreases.

The invention according to claim 8 is the invention according to claims 1 and 2,
An epitaxial wafer for a hetero-bipolar transistor manufactured using the method for manufacturing a semiconductor wafer described in 3, 4, 5, 6, or 7. An HBT epitaxial wafer having good film thickness uniformity and improved current amplification factor β and device life is provided, and it is possible to greatly improve the yield and characteristics of HBT devices.

The gist of the present invention resides in the use of TEG as a Ga source in the growth of an AlGaAs emitter layer, thereby providing a good GaAs base layer using CBr _{4 even} at an optimum growth temperature of 500 ° C. to 550 ° C. An emitter layer can be grown in a material transport rate-controlling mode in which film thickness uniformity can be obtained.
To grow an AlGaAs emitter layer having a sufficiently low oxygen and carbon concentration substantially equivalent to that of an AlGaAs crystal having a growth temperature of about 600 ° C. using a semiconductor layer, and changing the growth temperature between the base layer and the emitter layer. There is no need to interrupt growth, and a base-emitter interface with very few defects can be realized.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

(Embodiment 1) FIG. 2 shows the structure of an AlGaAs / GaAs HBT wafer according to a first embodiment of the present invention. In FIG. 2, a collector contact layer 2 and a collector layer 3 are stacked on a semi-insulating GaAs substrate 1. N of the collector contact layer 2 has a thickness 500 nm, carrier concentration 5 × 10 ¹⁸ cm ^{-3 +} -type GaA
The collector layer 3 is composed of an n ⁻ -type GaAs layer having a thickness of 500 nm and a carrier concentration of 2 × 10 ¹⁶ cm ⁻³ .

Reference numeral 4 denotes a p ⁺ -type Ga layer formed on the collector layer 3 and having a thickness of 100 nm and a carrier concentration of 4 × 10 ¹⁹ cm ^-3.
An As base layer, on which an emitter layer 5 is formed.

The emitter layer 5 is made of n-type Al _0.25 G having a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ and a thickness of 120 nm by Si doping.
a _0.75 As layer 5a and a carrier concentration 5 × 10 ¹⁷ by Si doping, grown on this layer 5a by gradually decreasing the AlAs mixed crystal ratio x from 0.25 to 0.
and an n ⁺ -type Al _x Ga _{1 -x} As graded layer 5b of cm ⁻³ to 5 × 10 ¹⁸ cm ⁻³ .

On the emitter layer 5, an n ⁺ -type GaAs layer 6 a having a thickness of 100 nm and a carrier concentration of 5 × 10 ¹⁸ cm ⁻³ by Si doping is formed as an emitter contact layer 6.
And a thickness of 50 nm formed on this layer 6a and a carrier concentration by Se doping of 1 × 10 ¹⁹ cm ⁻³ to 4 × 10 ¹⁹
cm ⁻³ n ⁺ -type In _y Ga _{1 -y} As (y = 0 → 0.5) graded layer 6 b, 50 nm thick formed on graded layer 6 b, carrier concentration by Se doping 4
× 10 ¹⁹ cm ⁻³ n ⁺ type In _0.5 Ga _0.5 As layers 6c are sequentially stacked.

Next, a method for manufacturing the above-described epitaxial wafer for HBT will be described.

Metal organic vapor phase epitaxy MOVPE (Metal Or
The wafer structure shown in FIG. 1 is epitaxially grown by the ganic vapor phase epitaxy method. Growth materials include:
Triethyl gallium (TEG), Al as a raw material of Ga
TMAl (trimethylaluminum) or T as raw material
EAl (triethylaluminum), As raw material A
sH ₃ (arsine) is used. Further, disilane (Si ₂ H ₆ ) and hydrogen selenide (H ₂ Se) are used as n-type dopant raw materials, and carbon (C) halides (CBr ₄ , CCl _4, etc.) are used as p-type dopant raw materials.

A semi-insulating GaAs substrate 1 is placed on a susceptor in a reaction tube (not shown), and the susceptor is heated by a high-frequency coil to heat the GaAs substrate 1.

When growing the GaAs layers 2, ₃ , 4, 6a, TEG (triethyl gallium) and AsH ₃ (arsine) are fed into a reaction tube, and TEG and AsH ₃ are thermally decomposed on the GaAs substrate 1, A GaAs crystal is grown. In the case of crystals of the AlGaAs layers 5a and 5b, TEG, TMAl (trimethylaluminum) and A
Simultaneously flow sH ₃ and grow continuously in the same reaction tube.

When growing the compound semiconductors of the collector contact layer 2, the collector layer 3, the base layer 4, the emitter layer 5, and the emitter contact layer 6, the growth temperature is set to a constant temperature in the range of 500 ° C. to 550 ° C. Keep and grow.

As the doping material, the collector contact layer 2 and the collector layer 3 are doped with Si using disilane Si ₂ H ₆ as a dopant material. Here, CBr ₄ is used as a doping material for the base layer 4 as a C halide. Further, the n-type Al
_{The 0.25} Ga _0.75 As layer 5 a is also doped with Si using Si ₂ H ₆ . Then, for the n ⁺ -type InGaAs emitter contact layer 6, hydrogen selenide (H ₂ S
e) is doped with Se.

First, in order to grow an n ⁺ -type GaAs crystal as a collector contact layer 2 on a semi-insulating GaAs substrate 1, Si ₂ H ₆ (disilane) as a dopant gas is simultaneously flowed into TEGa and AsH ₃ gas. Growing a GaAs crystal while doping a large amount of Si into the gas.
When an n ⁻ -type GaAs crystal is grown thereon as the collector layer 3, Si ₂ H ₆ is added to TMG and AsH ₃ gas.
At the same time to grow an n ⁻ -type GaAs crystal while doping a small amount of Si.

The base layer 4 has a carrier concentration of 4 × using a halide CBr _{4 of} C as a doping material.
A p-type GaAs of 10 ¹⁹ cm ^-3 and a thickness of about 100 nm is grown. In this case, the supply amount of the halide of C is fixed,
The carrier concentration and the film thickness of the base layer 4 made of p-type GaAs can be controlled by changing the supply amount of the group V raw material and controlling the C concentration. Here, the growth temperature is 520 ° C., the CBr ₄ flow rate is 4.9 × 10 ⁻² cc / min,
The EGa flow rate was 2.0 cc / min. Under these conditions,
When the AsH ₃ flow rate was changed from 13 to 98 cc / min, the carrier concentration changed from 0.6 to 3.3 × 10 ¹⁹ cm ⁻³ . On the other hand, the growth rate is constant even when the flow rate of AsH ₃ is changed.
The reason why carbon (C) was adopted as the GaAs p-type dopant for the base layer 4 is that C has a small diffusion constant,
This is because the BT element has a long life and high reliability.

Next, the crystal of the emitter layer 5 is grown continuously at the same temperature as that of the base layer 4, that is, at 520 ° C. without any interruption time for raising the temperature. This emitter layer 5
AlGaAs n-type AlGaAs layer 5a, when growing 5b crystals, TEGa, flow Si ₂ H ₆ dopant gas in the gas TMAl and AsH ₃ (the disilane) simultaneously, while Si doping in the gas as Grow crystals.

N ⁺ -type Ga as emitter contact layer 6
When growing a crystal of an As layer, TEGa and AsH _{3 are used.}
Of hydrogen selenide (H ₂
Se) is simultaneously flowed, and an n ⁺ -type GaAs crystal is grown while doping Se into the gas in a large amount.

FIG. 1 shows details of a portion where the growth conditions are changed between the conventional method and the manufacturing method of the above embodiment. For comparison, the conventional method and the method according to the present embodiment have different HB values.
An epitaxial wafer for T was grown, and an HBT having an emitter size of 100 μm square was manufactured by a simple process, and the current amplification factor β at a current density of 10 ³ A / cm ² was compared. Note that AlGaAs grown using TEG as a Ga source was used.
In order to confirm the effect of the s emitter layer, the growth conditions were the same except for the method of forming the emitter layer and the base-emitter interface.

As a result of evaluating the current amplification factor β, in the case of the structure example of FIG. 2, the current amplification factor β of the HBT grown by the conventional method is about 29,
The current amplification factor β of T was 62, which could be improved about twice. It is considered that the improvement of the current amplification factor β has been made possible by greatly reducing defects at the interface between the base and the emitter layer while maintaining the quality of the emitter layer at the same level as in the related art. Further, it has been found that this defect has a large effect on the life of the HBT element and has an effect.

Therefore, according to the present invention, it can be said that defects at the interface between the base and the emitter layer of the HBT can be greatly reduced, and that the life of the device can be considerably improved.

In the above embodiment, TEG and TMA
The growth temperature of the AlGaAs emitter layer using
C., but this temperature can be arbitrarily set in the range of 500.degree. This is based on the following grounds.

First, the growth concentration range of each single crystal was examined. In the case of a GaAs crystal using TEG and arsine as the raw materials, the temperature range in which the raw materials were transported with good film thickness uniformity and the rate was controlled was approximately 400 ° C. to 550 ° C. In the case of an aluminum arsenide (AlAs) crystal using TMAl and arsine as the raw materials, the lower limit of the temperature range in which the growth is controlled by the raw material transport with good uniformity of the film thickness is surprisingly higher than that of about 550 ° C. which has been conventionally considered. Cold 50
It was found that the temperature was about 0 ° C. From both, TEG and T
In the case of an AlGaAs crystal using MAl and arsine, the temperature range in which the growth of the source with the uniformity of the film thickness being uniform is limited to 50.
It is estimated to be 0 ° C to 550 ° C. In the above embodiment, 520 ° C. is set as a substantially middle value of this temperature range.

When AlGaAs was actually grown in this temperature range of 500 ° C. to 550 ° C. using TEG and TMAl, it was confirmed that the film thickness uniformity and the Al mixed crystal ratio were sufficiently good. Conversely, it was also confirmed that when the temperature deviates from this temperature range, the uniformity gradually deteriorates.

(Embodiment 2) As a second embodiment, an undoped GaAs spacer layer (not shown) having a thickness of 4 nm is provided between the base layer 4 and the emitter layer 5, and has the same structure as that of FIG. HBT was manufactured. The manufacturing method thereof is the same as that of the first embodiment except that the number of steps of growing the spacer layer increases after the step of growing the base layer 4.

In manufacturing the HBT epitaxial wafer of the second embodiment, after the growth of the base layer 4, at the same temperature as the base layer 4, that is, at 520 ° C., between the base layer 4 and the emitter layer 5. An undoped GaAs spacer layer (not shown) having a thickness of 4 nm was grown. this is,
This is to prevent carbon, which is a p-type dopant, from entering the emitter layer, and to eliminate a gap between the hetero interface and the pn interface to some extent.

Next, the crystal of the emitter layer 5 was continuously grown at the same temperature as that of the base layer 4, more precisely, at the same temperature as that of the spacer layer, that is, at 520 ° C. without any interruption time for raising the temperature. .

In the second embodiment, undoped Ga
Although the thickness of the As spacer layer is 4 nm, the thickness may be 1 to 8 nm.

This thickness was also determined experimentally. An HBT epitaxial wafer was grown under exactly the same growth conditions (growth conditions described in the first embodiment) except for the spacer layer, and an HBT having an emitter angle of 100 × 100 μm was formed by a simple process, and the current density was 10 ³ A / cm ^2. The current amplification factor β was measured. As a result, the current amplification factor β is higher when the spacer layer is 1 nm thick than when the spacer layer is not provided,
The maximum value was obtained at about 5 nm, and when it exceeded 8 nm, the value was the same as that without the spacer layer. This means that if you put in a spacer layer,
This is presumably because carbon as a p-type dopant can be prevented from entering the emitter layer, and the deviation between the hetero interface and the pn interface can be eliminated to some extent. If the spacer layer is too thick, it becomes a barrier to electrons injected from the emitter layer into the base layer, so that it is considered that the collector current decreases and the current amplification factor β decreases.

<Modification> In the above embodiment, TMAl was used as the Al source, but it is considered that the same effect can be obtained by using triethyl aluminum (TEAl) instead of TMAl.

[0047]

As described above, according to the present invention, the following excellent effects can be obtained.

(1) The production method according to any one of claims 1 to 8,
AlG using MOVPE method or gas source MBE method
In the growth of the aAs emitter layer, TEG is used as a Ga source, and the growth temperature of the emitter layer is higher than the growth temperature of the base layer.
Since the temperature is set to 50 ° C. or less, G using CBr ₄
The emitter layer can be grown in the source-transporting rate-controlling mode in which good film thickness uniformity can be obtained even at the optimum growth temperature of the aAs-based base layer of 500 ° C. to 550 ° C. It is possible to grow an AlGaAs emitter layer having a sufficiently low oxygen and carbon concentration substantially equal to that of an AlGaAs crystal having a growth temperature of about 600 ° C. Accordingly, there is no need to interrupt the growth for changing the growth temperature between the base layer and the emitter layer, and a base-emitter interface with very few defects can be realized. Further, even when there is a difference between the growth temperature of the base layer and the growth temperature of the emitter layer, the temperature difference is smaller than the conventional temperature difference requiring growth interruption, so that the growth interruption time can be shorter than before.

(2) In the manufacturing method according to the third aspect, A
The growth temperature of the lGaAs emitter layer is set to 500 ° C. to 550 ° C.
The temperature range is 400 for growing GaAs crystals with good film thickness uniformity using TEG and arsine as raw materials.
C. to 550.degree. C., and the lower limit of the temperature range of about 500.degree. C. for growing AlAs crystals with uniform film thickness using TMAl and arsine as raw materials is also satisfied, and both TEG, TMAl and arsine are used. AlGa
An As crystal can be grown at a rate of controlling material transport with good uniformity of film thickness.

(3) In the manufacturing method according to the sixth aspect, since the epitaxial growth temperatures of the base layer and the emitter layer are made to coincide with each other, there is no growth interruption time subsequent to the base layer, that is, without raising the temperature. Thus, the emitter layer can be efficiently grown.

(4) In the manufacturing method according to the seventh aspect, an undoped G layer having a thickness of 1 to 8 nm is provided between the base layer and the emitter layer.
Since the aAs spacer layer is grown, the function of this spacer layer can suppress the entry of carbon, which is a p-type dopant, into the emitter layer, and can eliminate the misalignment between the hetero interface and the pn interface to some extent.

(5) Since the epitaxial wafer according to the eighth aspect is an epitaxial wafer for a hetero-bipolar transistor manufactured by using the manufacturing method according to the first to seventh aspects, it has good film thickness uniformity. In addition, an epitaxial wafer for HBT with improved current amplification factor β and device life is provided, and it is possible to greatly improve the yield and characteristics of the HBT device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a manufacturing method of the present invention in comparison with a conventional method.

FIG. 2 is a view showing a structural example of an epitaxial wafer for HBT to which the manufacturing method of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semi-insulating GaAs substrate 2 Collector contact layer 3 Collector layer 4 Base layer 5 Emitter layer 6 Emitter contact layer

Claims (8)

[Claims] A collector contact layer exhibiting n-type conduction, a collector layer exhibiting n-type conduction, and a GaAs exhibiting p-type conduction by MOVPE or gas source MBE.
A semiconductor wafer in which a base layer made of a crystal, an emitter layer made of an AlGaAs crystal exhibiting an n-type conductivity that forms a hetero junction with the base layer, and an emitter contact layer exhibiting an n-type conductivity are sequentially grown. Wherein the epitaxial growth of the emitter layer uses triethylgallium (TEG) as a gallium (Ga) source, and the growth temperature of the emitter layer is not lower than the growth temperature of the base layer and not higher than 550 ° C. Manufacturing method. 2. The method of manufacturing a semiconductor wafer according to claim 1, wherein trimethyl aluminum (T) is used as an aluminum (Al) source during the epitaxial growth of the emitter layer.
(MAl). 3. The method of manufacturing a semiconductor wafer according to claim 2, wherein the epitaxial growth temperature of the emitter layer is set at 500.
A method for manufacturing a semiconductor wafer, which is performed at a temperature of from 550C to 550C. 4. The method of manufacturing a semiconductor wafer according to claim 3, wherein triethylgallium (TEG) is used as a gallium (Ga) source during epitaxial growth of the base layer. 5. The method of manufacturing a semiconductor wafer according to claim 4, wherein carbon tetrabromide (CBr ₄ ) is used as a p-type dopant during epitaxial growth of the base layer. 6. A method for manufacturing a semiconductor wafer according to claim 5, wherein the base layers and the emitter layers have the same epitaxial growth temperature. 7. The method for manufacturing a semiconductor wafer according to claim 6, wherein an undoped GaAs spacer layer having a thickness of 1 to 8 nm is grown between the base layer and the emitter layer. 8. An epitaxial wafer for a hetero-bipolar transistor manufactured using the method for manufacturing a semiconductor wafer according to claim 1, 2, 3, 4, 5, 6, or 7.