JPS61174193A - Molecular beam epitaxial growth method - Google Patents

Abstract

PURPOSE:To grow the compd. of group III-V elements including high-quality Al at the substrate temp. lower than ever by incorporating Ga or In into an Al vaporization source, and carrying out the molecular beam epitaxial growth of the compd. of group III-V elements including Al. CONSTITUTION:The molecular beam epitaxial growth of the compd. of group III-V elements including Al (e.g., an AlGaAs liq. crystal) is carried out by incorporating 1-10 atom% Ga or In into an A vaporization source. A compd. of group III-V elements including high-quality Al can be grown at the substrate temp. lower than ever. By the previous addition of Ga or In into the Al vaporization source, a part of Ga of In into the Al vaporization source, a part of Ga or In takes in O2 by the reaction with the Al oxide under heating to form the oxide of Ga or In. Since the oxide is more vaporizable than the Al oxide and Ga or In is more vaporizable than Al, extremely high-purity Al remains in the crucible. Consequently, the O2 in the Al flux is remarkably reduced, and the compd. of group III-V elements including high-purity Al can be grown by the molecular beam epitaxial growth method.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a molecular beam epitaxy growth method for high-quality ■-■ compound semiconductors containing aluminum. [Prior Art] ■-V compounds containing aluminum Molecular beam epitaxy (hereinafter referred to as MBE) is an important technology for the production of semiconductor devices such as semiconductor radars.A typical example of a ■-■ compound containing aluminum is aluminum-gallium-arsenic mixed crystal (hereinafter referred to as phantom). (referred to as tsuaAs).

[Problem that the invention seeks to solve]

By the way, the MBE growth of high-quality A-tap aA- is much more difficult than the MBE growth of GaAs that does not contain Aj. The main reason for this is the 16th Annual Body Element Conference (1939).
9th year, Kobe) Extended Abstract 197
As described on pages 200 to 200, since U tends to combine with oxygen, oxygen is incorporated into the phantom aAs during MBE growth. High-purity U is put into a mixture of high-purity Iron nitride and heated to 1000° C. or higher to evaporate it. Ga and S are evaporated in a similar manner to obtain MujGm.
Grow Am. The reason why it is difficult to improve the quality of AjGaAs is that oxygen is mixed into the gas that evaporates from the gas.

When the growth temperature ° (substrate temperature) is low, the oxygen momme a
A- Incorporated into the growth layer and reduces the quality of Aμ iml. Therefore, high-quality AjGmAm can be obtained by low-temperature MBK growth.
In order to obtain this, it was necessary to reduce the amount of oxygen generated from the evaporation source.

An object of the present invention is to provide an MBE growth method for improving the quality of a 1-2 compound semiconductor containing U.

[Means for solving problems]

In the present invention, 1 to 10 atoms of gallium (Ga) or indium (In) are mixed into an At evaporation source.
A molecular beam epitaxy growth method characterized by performing molecular beam epitaxy growth of a ■-v group compound containing t.

[Action/Principle]

Although the high purity kl used for MBE growth has a high purity inside, the surface is covered with an oxide mainly composed of alumina (A1203). Oxygen contained in the At flux and gas during growth is released by decomposition of this oxide.

In the present invention, Ga or In is added in advance together with red as an evaporation source. A part of the added Ga or In reacts with the KAt oxide during heating and releases oxygen.
Create Ga or In oxide. Ga or In
The oxide of G evaporates much more easily than the oxide of At.
1 or In also evaporates more easily than At. therefore,
During heating, the oxide and Ga or In evaporate, leaving a truly pure red color in the syrup. For this reason, A
Oxygen in the t-flax and gas is greatly reduced, resulting in high-purity kt
A -v compound containing the following can be grown from MBEK.

〔Example〕

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

FIG. 1 is a diagram schematically showing an MBE apparatus used in an embodiment of the present invention. In the figure, 1 is a vacuum container, 2 is a GaAg substrate,
3 is an arsenic (A-) heating furnace, 4 is a Ga heating furnace, 5 is an At heating furnace, and 6 is a Si heating furnace. Each furnace has a Ruth? is built in, and Ruth has an evaporation source inside. 99.9999% At in Ruth I of At heating furnace 5
279 and 99.99999% Ga3jl, 10
Heated in vacuo at 50° C. for 10 hours. 01 in the At evaporation source before heating is 5 atoms, and the volume of the evaporation source is 10.5
It was cc. Since G1 has a vapor pressure 25 times higher than At at 1050°C, all of it evaporated during 10 hours of heating. The volume of the evaporation source after heating was 9.6 cc. After heating for 10 hours, 1 sl was removed using an At evaporation source at 0 cm-'
Doped A10030m0.7A8 on GaAs substrate 2
A layer of 1.0 μm thick was grown on top. Growing GaAs substrate 2
The temperature was maintained at 520°C. Successful At6.5G *
o, 7 A The 7 otoluminescence intensity of a is Ga
30% compared to when grown at the same substrate temperature (520°C) using a U evaporation source heated at 1050°C for 10 hours without adding
It was twice as big. Moreover, this strength is similar to that of Atg grown at a substrate temperature of 700°C using an evaporation source without adding Ga to At, 5G.
ao and 7AI. That is, by using a Ga-added U evaporation source, it has become possible to grow high-quality AtGaAm at a temperature 180° C. lower than before.

This is clearly because harmful impurities in the At flux were removed by the method of the present invention. As a result,
The density of impurities incorporated into AtGaAm was reduced, resulting in higher quality. Even with conventional A/, evaporation sources, the substrate temperature can be reduced to 52
High quality juGaAm can be obtained by increasing the temperature from 0°C to 700°C. This indicates that the adhesion coefficient of impurities to the crystal surface is sensitive to the substrate temperature. Oxygen can be considered as such an impurity. This is because even if the aluminum in the ruts crab is of high purity, the surface is covered with At oxides, and when heated and melted, the oxides dissolve into the U. Because the dissolved At oxide has a low vapor pressure, the heated layer does not disappear over a long period of time, and it continues to work as a source of trace amounts of oxygen in the At flux.When oxygen adheres to the AtDaAm surface, it generates many crystal defects. , At7, oxygen reduction in the gas is extremely important.

Ga is added in advance to the At evaporation source according to the example. Qa reacts with At oxide to take away oxygen and become Qa oxide. Qa oxide has a high vapor pressure, so the temperature is 1050℃
It is evaporated by heating for 10 hours, and the amount of oxygen in the At evaporation source is greatly reduced. For this reason, high quality A
s growth became possible.

On the other hand, in order to obtain high quality AtGaAs using the conventional MBE growth method, it was necessary to maintain the substrate temperature at a high temperature of 700°C. This temperature is 10 times higher than the decomposition temperature of GaAs.
Because it is as high as 0°C, it is not possible to obtain a smooth ωmAg surface, and when trying to fabricate a semiconductor radar, etc., A&iAa and G
Sufficient optical output could not be obtained because the aAs interface was degraded. In the MBE growth method according to this embodiment, high-quality AtGaAg can be grown at a low temperature of 520° C., so the surface is smooth and there is no blemish at the interface between AtGaAs and GaAs. Therefore, it has become possible to fabricate a semiconductor laser with high optical output.

〔Effect of the invention〕

As explained above, according to the molecular beam epitaxy method of the present invention, high quality m-containing U-containing
■ Compounds can grow. In the example, Ga added to α
is assumed to be 5 atoms, but experimentally, great effects were obtained with 1 or more atoms.

At 10 atoms or more, heating for 20 hours or more is required until Ga in the At evaporation source is exhausted, and the amount of At also decreases, which is not practical. Further, in the embodiment, Ga was used as the material added to At, but indium (In) may also be used. In particular, when growing an m-2 compound containing KIn and At, it is preferable to add In. The method of the present invention comprises At
Since this is a method for highly purifying the evaporation source, it goes without saying that this method can be applied to the growth of all group (IV) compounds containing At other than AtGaAs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of a molecular beam epitaxy apparatus used in an example of the present invention. 10-...Vacuum container, 2-6...Heating furnace.

Claims (1)

[Claims] (1) A molecular beam epitaxy growth method characterized by mixing 1 to 10 atomic % of gallium or indium in an aluminum evaporation source to perform molecular beam epitaxy growth of a III-V group compound containing aluminum.