JP2754549B2 - Ga <bottom 0>. ▲ lower 5 ▼ In ▲ lower 0 ▼. (5) Method of growing P crystal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor crystal.

Ga _0.5 In _0.5 P lattice matched to (prior art) GaAs substrate is a crystal of a basic promising AlGaInP system as a material for a visible semiconductor laser, the active layer of the semiconductor laser. The atomic arrangement of the active layer of this semiconductor laser is Ga, In, Ga, In.
A new degree of freedom can be added to the electro-optical properties by using a superlattice structure such as a structure in which Ga and In are alternately and regularly arranged on the group III sublattice of the 0) plane.

Conventionally, a Ga _0.5 In _0.5 P crystal lattice-matched to a GaAs substrate by a metal organic chemical vapor deposition method (MOVPE method)
Using a substrate whose growth surface is inclined by 2 ° in the [011] direction from the 01) plane, the material gas flow rate during crystal growth is kept constant at a growth temperature of 550 to 750 ° C and a V / III ratio of 500 or less, Was growing. When Ga _0.5 In _0.5 P crystal is grown under the above conditions, the band gap energy (Eg) at room temperature of Ga _0.5 In _0.5 P at room temperature remains lattice-matched to the GaAs substrate depending on the combination of the growth temperature and the V / III ratio. It had changed to 1.91 eV. This change in band gap energy was caused by a difference in atomic arrangement in the group III sublattice in the Ga _0.5 In _0.5 P crystal. That is, Ga and In on the group III sublattice are contained in a crystal having a band gap energy of 1.85 eV.
Is formed, and in a 1.9 eV crystal, Applied Physics Letters (Appl. Phys.), In which the group III atoms Ga and In are randomly arranged in the group III sublattice.
Lett.) 50: 673-675, 1987).

However, with the same phase or in the same direction,
It has not been possible to control the size of the region where the periodic superlattice is formed.

(Problems to be Solved by the Invention) Therefore, when a semiconductor element is manufactured using a superlattice, desired characteristics cannot be obtained.

However, until now, no method has been provided for controlling the size of a region where a superlattice having the same phase is formed.

The object of the present invention is to solve the above problems, phase, direction,
An object of the present invention is to provide a growth method for growing a Ga _0.5 In _0.5 P crystal having a superlattice structure while controlling periodicity and maintaining a constant flow rate of source gas during MOVPE growth.

(Means for Solving the Problems) In the present invention, Ga _0.5 In lattice-matched to a GaAs substrate is used.
_{A 0.5} P crystal is grown by MOVPE method at a temperature of 500 to 800 ° C., a net gas flow ratio (V / III ratio) of group V to group III of the raw material gas of 900 or less, and gallium and isodium are grown. An organic metal gas is allowed to coexist in the reaction tube to flow and grow, changing the combination of the growth temperature and the V / III ratio, and forming the growth surface of the GaAs substrate from a plane equivalent to the (001) plane. Ga _0.5 In _0.5 P by controlling the direction of deviation from the (001) plane using a plane with an angle within 10 °
Changes the superlattice structure formed in the crystal and controls the superstructure.

(Function) A superlattice structure in a Ga _0.5 In _0.5 P crystal on GaAs grown by MOVPE can be grown as follows.

FIG. 2 shows the relationship between the Eg of a Ga _0.5 In _0.5 P crystal lattice-matched to a GaAs substrate having a plane inclined by 2 ° in the [011] direction from the (001) plane, and the growth temperature, V / III ratio, and hole concentration. Is shown. The X axis represents the growth temperature, the Y axis represents the V / III ratio, and the Z axis represents the energy gap. P in FIG. 2 represents the hole concentration. Here, the V / III ratio and the hole concentration during the growth of the Ga _0.5 In _0.5 P crystal are changed as follows.

Ga _0.5 In _0.5 P Using trimethyl indium or triethyl indium as a group III In source for crystal growth, using trimethyl gallium or triethyl gallium as a Ga source, fixing the In and Ga source gases at a constant value, respectively, and reacting. V / II by changing the flow rate of PH ₃ using phosphine (PH ₃ ) as a group V raw material
Change the I ratio. Here, the group III flow rates are Ga and In
Is the sum of the net flow rates of the respective source gases.
When the hole concentration is p ≦ 1 × 10 ¹⁸ cm ⁻³ or less, the growth concentration is 60%.
Ga _0.5 In _0.5 P energy gap (E) lattice-matched to the GaAs substrate in the range of 0 to 750 ° C and the V / III ratio of 60 to 450.
g) varies continuously from 1.84 to 1.91 eV. The relationship between the growth temperature, the V / III ratio, and Eg is a curved surface with a V / III ratio of 410 and a growth temperature of 650 to 700 ° C. at 1.84 eV as the bottom surface.

As described above, Ga _0.5 In _0.5 P on GaAs by MOVPE method
The Eg of Ga _0.5 In _0.5 P changes depending on the combination of the growth temperature, the V / III ratio, and the hole concentration due to p-type doping. Against Eg of less than 1.9eV above the Ga _0.5 In _0.5 P, the crystal having a superlattice structure. This relationship is preserved when the angle between the growth plane and the plane equivalent to the (001) plane is within 10 °.

Here, the superlattice on the group III sublattice is formed using the steps on the GaAs substrate as growth nuclei. GaAs substrate is (00
1) When the surface is close to the surface, the superlattice is 2
Ga and In are alternately formed in the [11] direction or the [11] direction perpendicular to the plane (110) of the tongue bond bond. When the steps on the GaAs substrate are formed in the [10] direction close to the [11] direction, that is, when the growth surface is a surface inclined from the (001) surface to the [10] direction, Ga _0.5 In _0.5 The superlattice formed in P is predominantly one in which Ga plane and In plane are alternately arranged in the [11] direction, and the superlattice in the [11] direction is hardly formed. Also, the angle between the growth plane and the (001) plane is changed from 0 ° to 1 °.
By changing the angle to 0 °, the ratio between the superlattice formed in the [11] direction and the superlattice formed in the [11] direction can be changed.

When the growth plane is inclined from the (001) plane in the [110] direction, superlattices in the [11] and [11] directions are formed at a ratio of approximately 1: 1.

(Example) Hereinafter, an example in which the superlattice in the Ga _0.5 In _0.5 P crystal grown by the MOVPE method is controlled will be described.

G of the plane inclined 2 ° from the (001) plane to the [10] direction on the substrate
An aAs substrate and a GaAs substrate inclined by 2 ° in the [011] direction from the (001) plane were used. Using trimethylindium and triethylgallium as group III raw materials, each 2.16 ×
The flow rates were fixed at 10 ⁻⁵ mol / min and 2.64 mol / min. Phosphine (PH ₃ ) was used as a group V material, growth temperature was 700 ° C, and group V flow rate / I
Growth was performed at a group II flow rate of 410. At that time, the above two types of GaA
The band gap energy of Ga _0.5 In _0.5 P on s substrate is 1.
It was 85 eV. FIG. 1 schematically shows the arrangement of superlattices in a Ga _0.5 In _0.5 P crystal whose growth plane is inclined by 2 ° in the [10] direction from the (001) plane. Ga face and In in [11] direction
The arrangement in which planes were alternately arranged as Ga, In, Ga, In, Ga... Was dominant. Also, in this crystal, Ga, In, Ga, Ga, In
.., Etc., were hardly observed and a uniform superlattice was formed over a wide range.

In addition, I in the Ga _0.5 In _0.5 P crystal grown on the GaAs substrate whose growth surface is inclined by 2 ° in the [011] direction from the (001) plane.
The arrangement of group II atoms was a mixture of a superlattice in which Ga planes and In planes were alternately arranged in the [11] direction and a superlattice in which Ga planes and In planes were alternately arranged in the [11] direction. Also, the size of the superlattice in phase was a plate-like size having an average length of 50 ° in the growth direction.

At the growth temperature of 750 ° and V / III ratio of 450, the above two types of GaAs
When Ga _0.5 In _0.5 P crystal was grown on the substrate, the band gap energy was 1.89 eV. The superlattice present in the crystal is less than that of the crystal grown at 700 ° C. and a V / III ratio of 410 in the previous embodiment, and the superlattice is partially formed in an aligned state. The relationship between the azimuth of the tilt and the azimuth of the formed superlattice was the same as in the previous example.

The same was true when the growth was performed at a growth temperature of 600 ° C. and a V / III ratio of 60.

Furthermore, when the growth temperature is 500 ° C and the V / III ratio is 30,
Growth was also possible at 800 ° C and a V / III ratio of 1750.

The relationship between the orientation of the growth substrate and the direction in which the superlattice structure is formed was obtained with good reproducibility. In addition, (00
1) The electrical and optical properties of Ga _0.5 In _0.5 P were not degraded within a range of 10 ° C. or less from the plane.

(Effect of the Invention) According to the present method, the direction in which the superlattice structure formed in the Ga _0.5 In _0.5 P crystal is formed can be controlled. By using this for a semiconductor device, a new degree of freedom can be added to the electrical and optical properties of the device.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a Ga _0.5 In _0.5 P superlattice structure grown on a plane inclined by 2 ° in the [10] direction from the (001) plane. FIG. 2 shows Ga lattice-matched to a GaAs substrate.
FIG. 4 is a diagram showing the relationship between the growth temperature of _0.5 In _0.5 P, the V / III ratio, and the band gap energy.

Claims (1)

(57) [Claims] 1. A GaAs substrate is placed in a reaction tube, a source gas containing a group III element and a dopant source gas are introduced into the reaction tube, and the substrate is placed on the GaAs substrate at a predetermined growth temperature. In a crystal growth method for forming a Ga _0.5 In _0.5 P crystal lattice-matched to a metalorganic vapor phase epitaxy, a gallium and indium organometallic gas is supplied to a reaction tube at a growth temperature of 500 to 800 ° C. and a V / III ratio of 1800 or less. The growth surface of the GaAs substrate is formed at an angle of 10 ° or less from a plane equivalent to the (001) plane, and the growth plane of the GaAs substrate is (00).
1) Controlling the superlattice structure formed on the group III sublattice of group III primitive Ga and In in the Ga _0.5 In _0.5 P crystal by controlling the direction of deviation from the plane equivalent to the plane. Characteristic crystal growth method.