JP2644992B2 - Method for manufacturing compound semiconductor crystal - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an epitaxial growth method such as ZnSxSe
_{The present} invention relates to a method for producing a II-VI compound semiconductor crystal such as _1- x (0 ≦ x ≦ 1).

[Technical background of the invention and its problems]

Semiconductor light-emitting devices from red to green using a compound semiconductor material have already been mass-produced, and further development for higher luminance is underway. Under such circumstances, the blue light emitting element, which is the only light emitting color lacking in the visible region, has not yet found a satisfactory manufacturing technology.

In order to obtain a blue light-emitting element, it is necessary that the band gap of the semiconductor material used exceeds 2.6 to 3.7 eV. Recently, II-VI group compound semiconductors have been attracting attention as semiconductors satisfying the band gap. Have been. Above all, the bandgap is 2.6 ~
Promising are zinc sulfide (ZnS), zinc selenide (ZnSe) and their mixed crystals (ZnSSe) in the 3.7 eV region. Hereinafter, these materials are collectively referred to as hardened zinc selenide (ZnSxSe ₁ -x: 0 ≦ x ≦ 1).

As a method of epitaxially growing a zinc sulfide selenide crystal, for example, a vapor phase growth method (MOCVD method) using an organic metal, which is a crystal growth method under non-thermal equilibrium conditions, or a molecular beam epitaxy method (MBE method) can be considered.

According to these methods, it is possible to grow a high-quality crystal in a mirror surface state in the group III-V, and it is also possible to obtain a lower resistance.

However, in groups II-VI, such as hardened zinc selenide,
Even with such a method, it is difficult to obtain a high-quality crystal, and the actual situation is that a zinc sulfide zinc selenide crystal sufficient for obtaining a light-emitting element has not been obtained.

[Object of the invention]

An object of the present invention is to provide a method for producing high quality zinc sulphide selenide crystal using the MOCVD method.

[Summary of the Invention]

In the present invention, when growing a zinc sulfide selenide crystal by MOCVD on a semiconductor substrate, a V-group element vapor pressure equal to or higher than a dissociation pressure of a V-group element of the semiconductor substrate at a growth substrate temperature is maintained. Based on the growth of zinc sulfide zinc selenide crystals, for example, Ga
After the As substrate is brought to a certain temperature, As is introduced and maintained in an As atmosphere, and then the As introduction is stopped, and the decomposition pressure of GaAs is set higher and lower than the decomposition pressure of organic Ga, thereby growing ZnSxSe1-x. It is characterized by starting.

〔The invention's effect〕

Generally, in a group III-V compound semiconductor crystal, the dissociation vapor pressure of a group III element such as Ga, In, or Al is low, and that of a group V element such as As or P is large. For this reason, the group V element evaporates first at a high temperature, and the surface of the substrate becomes a group III excess state. When a group II-VI compound semiconductor crystal is grown on this substrate, the excess group III element diffuses into the group II-VI compound semiconductor and becomes a donor impurity, making it difficult to control the carrier concentration near the interface. . Further, it may optically cause SA emission, which may hinder optical property control, particularly blue emission.

In addition, since the stoichiometry on the substrate surface is shifted, there is a problem that the crystallinity of the grown II-VI compound semiconductor crystal deteriorates and the surface morphology becomes rough. This phenomenon became more remarkable when the temperature of MOCVD was increased.

However, according to the present invention, the atmosphere of the group V element is maintained before the growth of zinc selenide on the semiconductor substrate, and the scattering of the group V element from the semiconductor substrate is prevented. , It can be kept as a mirror surface. Also, it has become possible to obtain a high-quality zinc sulphide selenide crystal formed on the base semiconductor substrate with a mirror surface and with reduced SA emission.

(Example of the invention)

An embodiment in which a ZnSe crystal is grown on a GaAs substrate will be described. Since ZnSe has a lattice constant close to that of GaAs, ZnS by MOCVD
Many attempts have been made to grow e / GaAs, but it has been difficult to obtain a crystal with good surface conditions and low SA emission with good reproducibility.

ZnSe crystals were grown on a GaAs substrate using dimethyl zinc (DMZ) as a Zn raw material and dimethyl cereed (DMSe) as a Se raw material. The growth conditions are as follows: DMZ supply amount 1.6 × 10 ^-5 mol /
min, DMSe feed rate 3.2 × 10 ^-5 mol / min, therefore VI / II te = 2.0
It is. The substrate temperature is 600 ° C., and the decomposition As pressure of GaAs at this time is 1010 ⁻¹⁰ atm. Under these conditions, 10% H ₂ diluted AsH ₃
Introduce 10 ^-4 atm as As pressure, then cut off the introduction of AsH ₃
When the s pressure dropped to 10 ^-8 atm (higher than the GaAs decomposition pressure and lower than the Mo material at this value), crystal growth was started.

The surface state of the ZnSe crystal layer obtained according to this embodiment can be obtained with a very clean mirror surface and as shown in FIG.
It was a PL spectrum. For reference, using the same raw materials, Zn on a GaAs substrate without the introduction of AsH ₃ in the same substrate temperature
Se crystals were grown. The surface of the obtained crystal layer was rough, and the PL spectrum had a strong SA. Second it
Shown in the figure.

As is clear from this, it has been found that the crystallinity is significantly improved under the conditions of the present invention as compared with the conditions conventionally used.

The present invention is not limited to the above embodiment. For example, other raw materials such as diethyl zinc (DEZ) and diethyl selenide (DESe) may be used as the organic metal compound raw material. As for the semiconductor substrate, in addition to the above-mentioned GaAs, a mixed crystal such as GaAsP, GaAl-As, and InAsP can be used.

[Brief description of the drawings]

FIGS. 1 and 2 show Zn grown by the present invention and the conventional method.
FIG. 3 is a view showing a PL spectrum of Se.

Claims (2)

(57) [Claims] When a group II-VI compound semiconductor crystal is epitaxially grown on a group III-V compound semiconductor substrate by vapor phase growth using an organic metal, the substrate is heated to a temperature at which a group V element evaporates. After that, the group V element is introduced, the pressure of the group V element is raised to maintain the atmosphere of the group V element, and then the introduction of the group V element is stopped. Lower than the decomposition pressure of
-A method for producing a compound semiconductor crystal, wherein crystal growth of a group VI compound semiconductor is started. 2. A III-V compound semiconductor substrate comprising GaAs, II-V
The group I compound semiconductor crystal is ZnSxSel-x (0 ≦ x ≦ 1), and ZnSxSel-x / GaAs
3. The method for producing a compound semiconductor crystal according to claim 1, wherein said compound semiconductor crystal has a structure.