JPH08288229A - Vapor growth method of compound semiconductor - Google Patents

Abstract

PURPOSE: To obtain a high-quality compound semiconductor layer comprising a steep doping profile by a method wherein TMGa is used as the transport raw material of Ga for a GaAs layer, TMAs is used as the transport raw material of As and the conductivity type of the GaAs layer is controlled. CONSTITUTION: A GaAs layer is epitaxially grown on a crystal substrate by the vapor growth method of a III-V compound semiconductor using an organometallic compound. At this time. TMGa is used as the transport raw material of Ga for the GaAs layer, and TMAs is used as the transport raw material of As. Then, the conductivity type of the GaAs layer is controlled. Thereby, without using a dopant intentionally, a required conductivity type and a required carrier concentration can be controlled easily. In addition, since an effect that the memory effect of a dopant represented by Zn is eliminated can be expected, a compound semiconductor layer structure comprising a steep carrier concentration profile can be formed easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth method for compound semiconductors, and more particularly to a method for epitaxially growing a III-V group compound semiconductor layer using a vapor phase growth method using an organometallic compound.

[0002]

2. Description of the Related Art A III-V compound semiconductor device such as a GaAs bipolar transistor has an n ⁺ -GaAs substrate (n to 1 × 10 ¹⁸ cm ^-3 ) 1 as shown in FIG.
On top, an n ^{− −} GaAs collector layer (n to 5 × 10 ¹⁶ cm
^-3 ) 2, p-GaAs base layer (p ~ 3 x 10 ¹⁷ c
m ⁻³ ) 3, n ⁺ − emitter layer (n to 5 × 10 ¹⁸ cm ⁻³ )
4 are sequentially grown epitaxially. Generally, a vapor phase growth method or an epitaxial growth method having excellent film thickness controllability, such as molecular beam crystal growth, is suitable for forming this kind of laminated structure. When the vapor phase growth method using an organometallic compound, that is, the MOVPE method is applied, it is generally III
Group and Group V elements gallium (Ga) and arsenic (As)
Trimethylgallium (TMGa) as a transport material
And arsine (AsH ₃ ) are used. The conductivity type and carrier concentration of each layer forming the laminated structure of FIG. 3 are n-type and p-type dopants such as selenium (Se) and zinc (Zn).
Hydrogen selenide (H ₂ Se) and dimethylzinc (DMZn), which are the respective transport raw materials, were used, and these were supplied and controlled together with the transport raw materials of the group III and group V elements.

[0003]

As is clear from the above description, the laminated structure shown in FIG. 3 can be formed by the conventional MOVPE method. However, in the above-described laminated structure formed by the conventional method, since the base layer 3 has a large diffusion coefficient and Zn having a memory effect is used as a dopant, Zn diffusion to the collector layer 2 and the emitter layer 4 and the like occur, and the sharpness is steep. There was a problem that a good carrier concentration profile could not be obtained.

[0004] The present invention has been made in view of such a point,
It is an object of the present invention to provide a method for epitaxially growing a high-quality compound semiconductor layer having a steep doping profile by controlling the conductivity type and carrier concentration by controlling the impurity concentration of a non-doped compound semiconductor layer without intentionally using a dopant.

[0005]

In order to solve the above problems, the present invention uses a transport source of a group V element which is used depending on the conductivity type and carrier concentration of a non-doped compound semiconductor layer when a compound semiconductor layer is epitaxially grown by the MOVPE method. It was made based on the finding that it strongly depends on the properties and supply amount of GaA on a crystal substrate by a vapor phase growth method of a III-V group compound semiconductor using an organometallic compound.
When epitaxially growing the s layer, the G of the GaAs layer is
TMGa is used as the transportation material of a and TM is used as the transportation material of As.
A vapor phase growth method of a compound semiconductor in which the conductivity type of the GaAs layer is controlled by using As.

The operation of this technical means is as follows. That is, with the above configuration, the required conductivity type and carrier concentration can be easily controlled without intentionally using a dopant. Moreover, since the effect of eliminating the memory effect of the dopant represented by Zn can be expected, a compound semiconductor laminated structure having a steep carrier concentration profile can be easily formed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. When epitaxially growing GaAs, III
TMGa as a transporting material for the group element Ga, AsH ₃ and trimethylarsenic (TMAs) as a transporting material for the group V element As
2 types were used. The MOVPE apparatus used was a horizontal high-frequency heating furnace, the furnace pressure during growth was 100 Torr, and the substrate temperature was 700 ° C.

FIG. 2 is a graph showing the dependency of the carrier concentration of the non-doped GaAs layer grown by using AsH ₃ and TMGa on the AsH ₃ supply amount, where the AsH ₃ supply amount is It was n-type at 250 cc / min or higher, and p-type at 150 cc / min or lower.
As the supply of s increases, the vacancy density of Ga increases,
Silicon and germanium contained in the raw materials enter the Ga vacancy and become n-type, and when the As supply amount is reduced, the vacancy density of As increases and carbon C generated by the thermal decomposition reaction of TMGa becomes As vacancy. Upon entering the Confucius, a p-type competing reaction occurs, becoming both n-type and p-type.

However, non-doped GaAs grown using TMAs and TMGa and not added with impurities
The carrier concentration of the layer was always p-type and relatively high with respect to the amount of TMAs supplied. This is because a large amount of carbon GaAs layer generated by the thermal decomposition reaction of TMAs itself is incorporated. It has been confirmed by SIMS analysis that the p-type impurity is carbon. Since carbon forms a shallow acceptor level in the GaAs layer, it exhibits good p-type characteristics. In this way, TMAs and TMG
The GaAs layer grown by using a can obtain a good p-type GaAs layer having a relatively high concentration by incorporating carbon without intentionally adding impurities.

The above results are shown in FIG.
It was used when forming a laminated structure of a bipolar transistor. The collector layer 2 and the emission layer are TMGa as before.
Flow rate 2 cc / min, AsH ₃ flow rate 200 cc / mi
n, total flow rate of source gas and carrier gas 5 liters / mi
The required n-type carrier concentration epitaxially grown under the condition of n was obtained by supplying H ₂ Se. The base layer 3 uses TMAs as a transport material for As, and has a TMGa flow rate of 2 cc / mi.
The epitaxial growth was performed under the conditions of n and TMAs flow rate of 100 cc / min.

FIG. 3 obtained by the above embodiment of the present invention.
FIG. 1 shows an impurity concentration profile in the depth direction by SIMS in the vicinity of the base layer 3 of the laminated structure of. The carbon concentration profile in the base layer grown by the vapor phase growth method of the present invention and the Zn concentration profile in the base layer grown by the conventional vapor phase growth method are shown for comparison. A compound semiconductor laminated structure having a steep profile can be formed with a required impurity concentration by the phase growth method.

This embodiment does not control the present invention. That is, AsH ₃ and T
Although the case where MAs individually form different epitaxial layers is illustrated, AsH ₃ and TMAs may be simultaneously used at a predetermined supply ratio, and other alkyl metal compounds, hydrogen compounds and metals may be used. The same effect can be expected. Further, although the case of forming the laminated structure of FIG. 2 is illustrated here, the present invention can be applied to other laminated structures. The growth conditions may also be changed depending on the device used and the situation.

[0013]

As is apparent from the above description, according to the present invention, a compound semiconductor layer having a required conductivity type or carrier concentration can be easily obtained without intentionally using a dopant, and the crystallinity of the compound semiconductor layer can be easily obtained. Is good.
Further, there is no memory effect of the dopant typified by Zn, and the profile of the impurity concentration is steep. Therefore, by using the present invention, a compound semiconductor laminated structure having good device characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an impurity concentration profile in a compound semiconductor laminated structure formed by a vapor phase growth method of the present invention.

FIG. 2 is a graph showing the dependency of the AsH ₃ supply amount on the impurity concentration.

FIG. 3 is a sectional view schematically showing a laminated structure of a GaAs bipolar transistor.

[Explanation of symbols]

 1 substrate 2 collector layer 3 base layer 4 emitter layer

Claims (3)

[Claims] 1. A GaAs on a crystal substrate by a vapor phase growth method of a III-V group compound semiconductor using an organometallic compound.
When the layer is epitaxially grown, the Ga of the GaAs layer is
TMGa is used as the transport material for
A method for vapor phase growth of a compound semiconductor, wherein s is used to control the conductivity type of the GaAs layer. 2. As a transporting material for Ga, TMGa is used,
A semiconductor device in which a p-type GaAs layer is formed by using TMAs as a transportation raw material. 3. Use of TMGa as a Ga transporting material
A bipolar transistor in which a p-type GaAs layer is formed by using TMAs as a transport raw material and the p-type GaAs layer is used as a base layer.