JPS63248795A - Molecular beam epitaxy - Google Patents

Abstract

PURPOSE:To form a crystal with less impurities of carbon by using specified aluminum as the raw material at the time of growing a III-V compd. semiconductor thin film contg. aluminum by the title molecular beam epitaxy method. CONSTITUTION:In the molecular beam epitaxy method using an organometallic compd. as the raw material, the organometallic compd. having at least one hydrogen is used as the raw material for aluminum to grow the III-V compd. semiconductor thin film contg. aluminum. For example, Al(CH3)2H, Al(CH3)H2, etc., can be used as the raw material for aluminum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a molecular beam epitaxial growth method using an organometallic compound as a raw material.

[Conventional technology]

In recent years, the development of high-speed logic devices, semiconductor lasers, and opto-electronic integrated circuits (ORICs) using m-v group compound semiconductors such as GaAs and A4GaAs has progressed rapidly, and as a result, sophisticated device manufacturing processes have become necessary. It's coming.

In the molecular beam epitaxial growth method (MBE method), elements turn into molecular beams and reach the substrate in a growth chamber maintained at a high degree of vacuum, so the film thickness can be controlled with high precision, and the molecular beams can be blocked by opening and closing a shutter. Therefore, it has the advantage of being able to obtain a steep Peter interface.

In addition, the molecular beam epitaxial growth method is an important technique for manufacturing the above-mentioned devices because it can grow a high-quality compound semiconductor thin film of the ■-■ group with less contamination of impurities.

Conventionally, metals such as Ga and AQ have been used as raw materials for molecular beam sources, and a molecular beam with an appropriate beam intensity has been obtained by placing the metals in a crucible and controlling the temperature of the cell.

In this method, depending on the raw material, it is necessary to heat the cell to a high temperature of 1000° C. or higher, which can cause impurity generation and failure. Furthermore, in order to exchange raw materials, it is necessary to open the vacuum state to the atmosphere, which also causes the problem of contamination with impurities.

So, recently 11. A molecular beam epitaxial growth method using organometallic compounds instead of metal raw materials has been attempted by T. T. and Tsang et al. (Journal of
V-accum 5science Technology
ogy B, Vol, 3 Na2 P-66
6-670, 1985).

This method not only solves the problem of the metal raw material mentioned above, but also has the advantage of reducing defects on the crystal surface and allowing selective growth.

Among organometallic compounds, those commonly used are trimethyl gallium (Ga(
CH3)i), triethylgallium (Ga (cz H
s))), trimethylaluminum (AM(C)li)z) as the AQ raw material.

triethylaluminum (Affi(C,Hs)i),
Trimethylindium (In(CH3
)i)-Triethylindium (In(C,H8))
), trimethyl arsenic (A
I(CH3)3), triethyl arsenic (As(czli)
, trimethyl phosphorus (P(CH))3) as a pfi material,
Triethyl phosphorus (P(C2Hs)1) and the like. In addition to organometallic compounds, group III raw materials include arsine (^sH,)
, phosphine (P) 13 ) and the like may also be used.

[Problem that the invention seeks to solve]

In the MBE method using the above-mentioned organometallic compound, G
Crystals using organometallic compounds as the Ga and In raw materials, such as aAs or InGaAs, have good purity, but crystals that use organometallic compounds as the ^Q raw materials, such as AQAs and AQGaAs, have extremely high purity. It is bad and shows a high concentration of P type.

Organometallic compounds decompose on or near the substrate,
It is said that it is adsorbed to the substrate in the form of an intermediate product containing one or two organic molecules. For example, taking Ga(CH3)3 as an example, it becomes monomethylgallium (GaCH3) and dimethylgallium (Ga(CH3)a), which are adsorbed to the substrate. These organics are eliminated by reacting with the group (Ⅰ) raw material. However, AQ(CL)3-AQ(C2
In organometallic compounds containing AΩ such as H9)3, the bonding energy between the organic and the metal is large, so even if it reacts with the V group raw material, the organic does not desorb and remains in the crystal, which causes carbon acceptors. The problem arises that it becomes a high P type.

An object of the present invention is to provide a molecular beam epitaxial growth method that eliminates the above-mentioned problems.

[Means for solving problems]

The present invention is characterized in that, in a molecular beam epitaxial growth method using an organometallic compound as a raw material, an organometallic compound having at least one hydrogen group is used as the aluminum raw material to grow an m-■ group compound semiconductor thin film containing aluminum. This is a molecular beam epitaxial growth method.

[Effect]

The present invention uses AQ(CH-)i-AQ(Cz
Hs)i is not used, but an organometallic compound having at least one hydrogen group, such as dimethylaluminum hydride Al2 (CFI, )2H, monomethylaluminum hydride AMCH, )El, etc. is used.

By using an organometallic compound with a hydrogen group as the AQ raw material, the adsorbed species of AQ becomes aluminum hydride AQ-H, which has a higher binding energy than organic, eliminating the cause of carbon incorporation into the crystal. can.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an apparatus used in an embodiment of the invention. This device consists of a growth chamber 1 maintained at an ultra-high degree of vacuum, an exhaust bag W2 for evacuating the inside of the growth chamber 1, a substrate holder 3 equipped with a heating mechanism, a nude ion gauge 4, and a group III raw material inlet. 5 and V group raw material inlet 6, and a mass flow controller 7.8 that controls the flow rate of the raw material to each of the inlets 5 and 6.
9.

In this example, Ga (CI(,), ,A
AQCCHs) tH as Q raw material, As as raw material
We attempted to grow AQGaAs using H. In addition, the flow rate is as follows: Ga(CHi)3 is ice/+ain, AQ(
CHz)zH is 0.5oc/wain, AsH, is 1
44^Q0.3Ga, 7As were grown on a semi-insulating GaAs substrate by controlling the growth rate to 0 cc/+min.

Hall measurements of the grown crystal showed that I
A P-type crystal with a carrier concentration of IO''(01-') was obtained, and was AQGaAs with a higher purity than the conventional one.

FIG. 2 shows the results of photoluminescence evaluation (PL) of this crystal at 4.2K. In this example, compared to the conventional example shown by the dotted line, the peak due to carbon acceptors is smaller, and it can be seen that the contamination of carbon is suppressed.

Although this example describes 1QGaAs, other m-v group compound mixed crystals including AQ, and AQAs/GaAs
Similar results can be obtained when growing superlattices such as

Further, other organometallic compounds having a hydrogen group may be used instead of u(cut)in.

〔Effect of the invention〕

As explained above, the molecular beam epitaxial growth method of the present invention has the effect of making it possible to obtain crystals with less carbon impurities when growing a thin film of a compound semiconductor containing AQ.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used in an embodiment of the present invention;
FIG. 2 is a PL characteristic diagram of 4.2 showing the effect of the present invention.

Claims (1)

[Claims] (1) In the molecular beam epitaxial growth method using an organometallic compound as a raw material, an organometallic compound having at least one hydrogen group is used as the aluminum raw material,
A molecular beam epitaxial growth method characterized by growing a III-V group compound semiconductor thin film containing aluminum.