JPH02102200A - Method for producing compound semiconductor crystal film - Google Patents

Abstract

PURPOSE:To enable growth at high reaction temperature and give theoretical band gap and excellent crystalline properties to an aimed film by introducing a raw material gas using a specific system in producing AlGaInP which is a material for visible semiconductor laser by an organometallic chemical vapor phase method. CONSTITUTION:GaAs substrate is set in a reactor made of quartz and heated to >=750 deg.C by induction heating by high-frequency coil while charging an arsenic gas (e.g., AsH2) into a reactor. Then a phosphorus gas (e.g., PH3) is introduced and after 1 second, a gas of the group III [e.g., Al(CH3)3, Ga(CH3)3 and In(CH3)3] and the phosphorus gas are simultaneously introduced and after 0-3 second, introduction of arsenic gas is stopped and growth of a compound semiconductor expressed by the formula AlxGayIn1-x-yP (0<=x<=1, 0<=y<=1 and 0<=x+y<=1) is started to provide the compound semiconductor crystal film.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to the use of AlGa, which is a material for visible light semiconductor lasers, etc.
The present invention relates to a method of growing and manufacturing InPk by a metal organic chemical vapor deposition method (hereinafter referred to as MOCVD method).

(Prior Art) AIGaInp has the largest band gap among the A-III group compound semiconductors and is an essential material for obtaining short wavelength semiconductor lasers. It is very difficult to grow this material using conventional techniques such as liquid phase epitaxial method (LPE method) and vapor phase epitaxial method (VPE method). L
In the PE method, it is almost impossible to control the composition because the segregation coefficients of A1, ()a, and In are too different. Also,
Similarly, the VPB method also has problems such as segregation of A1 and quartz-chloride reaction.

Therefore, recently, methods of growing the above-mentioned semiconductor crystal film by molecular beam epitaxial method (MBE method), MOCVD method, etc. have been studied. The MOCVD method is a vapor phase growth method for compound crystals using organometallic compounds as raw materials (Applied Physics, Vol. 48, No. 5, P460-465.1979)
. However, at present, MBE method and MOCVD method (
Among these, AlGaInP grown by the MOCVD method has the following drawbacks.

First, there are many crystal defects. In particular, this becomes more noticeable as the composition ratio of A1 increases. Deterioration of devices such as semiconductor lasers is due to weak point fracture, and occurs concentrated at such crystal defects.

In other words, the fact that there are many crystal defects means that the life of the element will be short when it is made into a device. Incidentally, at present, the lifetime of the AlGaInP semiconductor laser 8 is approximately several hundred hours.

Second, the actual wavelength of light emission is longer than the value calculated from the composition. (50 in terms of band gap)
It is about meV narrow. ) This is because the mixed state of group I atoms is not sufficient and AI, C) a is present on the group I sublattice.

This is thought to be due to the fact that each In atom is regularly arranged. Optical devices such as semiconductor lasers are required to have shorter wavelengths, but at present, even if AlGaInP systems are used, the wavelength of continuous oscillation at room temperature is about 680 nm, which is not much different from AIC) aAs systems.

In optical devices such as semiconductor lasers using AlGaInP, it has been a serious challenge to achieve longer lifetimes and shorter wavelengths.

(Problems to be Solved and Attempted by the Invention) Conventionally, Al()aIn
It has been difficult to create a long-life, short-wavelength semiconductor laser having the theoretical bandgap of the P system.

The present invention is aimed at solving the above-mentioned problems, and is directed to AIC)a having a theoretical band gap and excellent crystallinity.
The object of the present invention is to provide a method for manufacturing a compound semiconductor film that enables the production of excellent original devices such as long-life and short-wavelength semiconductor lasers by growing InP crystals on GaAs substrates.

(Means for solving the problem) Al (
) In order to obtain aInP, GaA,s
It is necessary to speed up the migration of each atom on the substrate, that is, to raise the reaction temperature higher than usual (750° C. or lower).

However, when growing AlGaInP on a GaAs substrate, the arsenic source gas is flowed into the reaction tube housed in the substrate tray (by applying arsenic pressure) to suppress the escape of arsenic from the aAs substrate and preserve the GaAs substrate before growth. After heating to the above reaction temperature, the arsenic raw material gas and the phosphorus raw material gas are exchanged, and then the group III raw material gas is introduced.
In the general gas introduction method of starting the growth of lGaInP, the film becomes cloudy at temperatures of 750° C. or higher. (The same effect can be obtained even if the interval between arsenic and phosphorus raw material gas exchange and Group 1 raw material gas introduction is varied.) This is because as the temperature increases, arsenic is more easily removed from the GaAs substrate, and a small amount of solder is removed. GaA also during the interval
This is thought to be due to deterioration of the s-substrate surface.

As a result of extensive research on methods to solve these problems, the present inventors have found that by improving the gas introduction method, it is possible to grow at a higher reaction temperature than before, υ, which is superior to the theoretical band gap. AlGaInP with crystallinity
It turns out that you can get .

That is, the present invention provides a method of forming a film with a composition AlyC)ayIrll -y-yP (D≦x≦
When growing a compound of 1.0≦y≦1.0≦x+'Y≦1), after heating to the above temperature while flowing arsenic gas into the vessel containing the GaAs substrate, phosphorus gas is introduced. Next, a gas belonging to Group 1 of the periodic table is introduced, and after introducing the gas belonging to Group 1 of the periodic table, the introduction of arsenic gas is stopped within 3 seconds, and the Al
This is a method for manufacturing a compound semiconductor crystal film, which is characterized by starting the growth of GaInP.

The present invention will be explained below. In the present invention, the order of introducing the phosphorous gas and the gases of Group 1 of the periodic law must be as described above. If this order is reversed, group I metals will first be deposited on the GaAs substrate, resulting in deterioration of crystallinity.

In addition, there is a time for arsenic, phosphorus, and each raw material gas of Group 1 of the periodic table to mix, but if this time is less than 6 seconds, this corresponds to a time lag of growth, and the AIGa
It was confirmed by observation using TEM etc. that there was no intermediate layer made of InAsP.

Gases of the YJL family that can be used include the following.

Al... trimethylaluminum (TMA),)
') Ethyl aluminum (TEA), tributyl aluminum (TBAI), etc.

C) a... Trimethyl gallium (TMG), triethyl gallium (TEG), etc.

In... triethylindium (TMI), triethylindium (TEI), ethyldimethylindium (EDMI), etc.

P...phosphine (PH3), etc.

As...Arsine (AsH3), ) ethylarsine (TEAs), etc.

(Example) FIG. 1 is a cross-sectional view showing the concept of the MOCVD crystal growth apparatus used. In the figure, 1\'i is a reaction tube made of quartz, into which the raw material mixed gas was introduced through the gas inlet 2, and the gas after the reaction was exhausted through the gas exhaust port 3.

A graphite fissure susceptor 4 was disposed inside the reaction tube 1, and a GaAs substrate 5 was set on the susceptor 4 and heated by induction by a high frequency coil 6.

Next, a crystal growth method using the above apparatus will be explained. First, GaA was interface-cleaned by chemical etching.
The s-substrate 5 was set on the susceptor 4 via a load lock system (a system consisting of two chambers, a reaction chamber and a front chamber, in which the reaction chamber is not exposed to the atmosphere when the substrate is carried in and out). High-purity hydrogen was introduced at a rate of 8.5 liters per minute through the gas inlet 2, and the pressure was maintained at 760 corr. Thereafter, AsH3 was introduced through the gas inlet 2, the susceptor 4 and the GaAs substrate 5 were heated by the high frequency coil 6, and the substrates were cleaned by holding the reaction temperature for 5 minutes.

Next, PH3'i was introduced, and 1 second later, TMA, TMG, and TMI, which had been adjusted to a predetermined mixing ratio, were simultaneously introduced, and then 1 second later (c1=Q~3), A was introduced.
The introduction of s H3 was stopped, and AlGaInP crystal growth was performed.

At this time, the temperature is measured by thermocouple 7 (Pz-PL
・16% Rh).

Figure 1 shows the results of two-crystal X-ray diffraction, photoluminescence, and surface defect measurements of AlGaInP grown at various temperatures and compositions. Composition determined by EPMA. Two-crystal method X-ray diffraction uses ()aAs single crystal as the first crystal.
4) Measure reflection. FWHM (half width at half maximum) is one of the criteria for determining the crystallinity of a crystal film, and narrowing and creeping are generally better.

Photoluminescence uses Ar silage (wavelength: 5145
X) Measured at 300K with excitation. Eg(PL) is a value calculated from the emission wavelength, Pg(th) is a theoretical value, and ΔEg is the difference between the two. The closer ΔEg is to 0, the more the crystal film has a theoretical band gap. -1 is the same as in the case of double-crystal method x#1 diffraction. Surface defect density was observed using a differential interference microscope. The smaller this value is, the better the crystallinity is.

It was confirmed by TEM observation that there was no intermediate layer such as AIGaInAsP at the interface with the GaAs substrate in each AlGaInP crystal.

(Comparative example) The only difference from the example was the gas introduction method, which was carried out as follows.

(General gas introduction method) AsH3f was introduced from the gas introduction port, the susceptor and the GaAs substrate were heated by a high frequency coil, and the substrate was cleaned by holding the reaction temperature for 5 minutes.

Next, after stopping the introduction of AsH3 and fully starting the introduction of PH3, 52 seconds later (t2 = 1 to 10), TMA, Tl/IG, and TMI, which had been adjusted to a predetermined mixing ratio, were simultaneously introduced to form the AlGaInP crystal. I grew up.

Figure 1 shows the results of two-crystal X-ray diffraction, photoluminescence, and surface defect measurements of AlGaInP grown at various temperatures and compositions.

(Effect of the invention) As described above, if the gas introduction method of the present invention is adopted, 7
It is possible to grow AlGaInP IFj crystals at temperatures above 50°C. This crystal has a theoretical band gap and excellent crystallinity, and is extremely effective in producing long-life, short-wavelength semiconductor radars.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the concept of an MOCVD crystal growth apparatus used in an example of the present invention. 1...Reaction tube 2...Gas inlet 3...Gas exhaust port 4...Susceptor 5...GaAs substrate 6...High frequency coil 7...Thermocouple patent applicant Denki Kagaku Kogyo Co., Ltd. Company Figure 1 1 ・ ・ 4 ・ 6 ・ ・ 7 ・ ・ Anti-I, 6 pipes...Gas introduction] Nido gas ur air port... Susceptor GaAsJ+T4 anti-high frequency coil thermocouple

Claims (1)

[Claims] (1) By metal organic chemical vapor deposition method (MOCVD method), 7
The composition Al_xGa is deposited on a GaAs substrate at a temperature of 50°C or higher.
_yIn_1_-_x_-_yP(0≦x≦1, 0≦y
≦1, 0≦x+y≦1), after heating the GaAs substrate to the above temperature while flowing arsenic gas into the chamber containing the GaAs substrate, phosphorus gas is introduced, and then After introducing the Group II gas of the periodic table, the introduction of arsenic gas was stopped within 3 seconds, and the AlGaInP
A method for producing a compound semiconductor crystal film, the method comprising starting the growth of a compound semiconductor crystal film.