JP2002326895A - Semiconductor crystal, method of growth, and photosemiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ZnO based crystal excellent in optical properties. SOLUTION: The method of growing semiconductor crystal of group II-V element on a substrate is comprised of following steps: (a) a step for preprocessing the substrate; (b) a step for growing a semiconductor crystal of group II-VI element on the surface of the substrate on a polar surface of group II element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor crystal and a method for growing the same, and more particularly, to a ZnO-based crystal, a method for growing the same, and an optical semiconductor device using the same.

[0002]

2. Description of the Related Art ZnO-based crystals are grown on a substrate by RF-MBE (also known as RS (radical source) -MBE) or laser ablation. As the substrate, for example, a sapphire substrate, ScAlM
A gO ₄ substrate, a ZnO substrate, or the like is used.

[0003]

By the way, many non-emission centers exist in ZnO crystals grown by the conventional method. When an optical semiconductor device is manufactured using a ZnO crystal having many non-light emitting centers, a problem occurs in optical characteristics. In addition, when doping the ZnO crystal with an impurity for imparting conductivity, the activation rate of the impurity is not good. It is necessary to supply more impurities during the growth, which causes problems such as difficulty in growing under high vacuum conditions or difficulty in growing a good crystal.

An object of the present invention is to grow a high-quality II-VI crystal having few non-light-emitting centers. further,
An object of the present invention is to improve the activation rate of impurities in a II-VI group crystal.

[0005]

According to one aspect of the present invention, there is provided a method for growing a group II-VI semiconductor crystal on a substrate, comprising: (a) performing a predetermined pretreatment on the substrate surface; (B) growing a group II-VI semiconductor crystal on the surface of the substrate on a polar plane of group II atoms.

According to another aspect of the present invention, there is provided an optical semiconductor device having a substrate, and a II-VI semiconductor crystal layer grown on the substrate at a polar plane of group II atoms.

According to yet another aspect of the present invention, a first cladding layer having a first conductivity type, comprising a substrate, a laminate formed on the substrate and including a II-VI semiconductor crystal layer, An active layer formed on the first cladding layer, and a second cladding layer formed on the active layer and having a second conductivity type opposite to the first conductivity type, At least one of the semiconductor crystal layers constituting the stack is a stack grown on the group II polar plane, and first and second electrically connected to the first clad layer and the second clad layer, respectively. An optical semiconductor device having an electrode is provided.

[0008] The semiconductor layer constituting the above-mentioned optical semiconductor element has particularly a small number of non-light-emitting centers and a good doping efficiency. Therefore, the optical semiconductor element has excellent optical characteristics.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor growth technique according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a schematic structure of a crystal growth apparatus based on the RF-MBE method. FIG. 2 shows that the ZnO layer grown on the sapphire substrate was subjected to the CAICISS method (C
oaxial Impact Collision I
on Scattering Spectroscop
It is a spectrum graph which shows the measurement result measured by y), and the simulation result. FIG. 3 shows the P of ZnO crystal.
It is a spectrum graph which shows the measurement result of L emission spectrum measurement.

FIG. 1 shows a high-frequency molecular beam epitaxy (R) as an example of an apparatus for growing a II-VI compound semiconductor crystal.
F-MBE) (hereinafter referred to as “RF-M”).
BE device ”. ).

The RF-MBE apparatus A includes a chamber 1 in which crystal growth is performed, and a vacuum pump P for keeping the chamber 1 in an ultra-high vacuum state. The chamber 1 has a Zn port 11 for evaporating Zn and a Mg port 11 for evaporating Mg.
Port 21 for irradiating O radicals, and an N radical port 41 for irradiating N radicals.

[0013] Zn port 11, Zn (purity 7N) Knudsen cell to heat-evaporated with containing ingredients 15 (Knudsen cell:. Hereinafter referred to as K cell) and a 17 and a shutter S _1.

The Mg port 21 contains a Knudsen cell (Knu) for containing the Mg raw material 25 and heating and evaporating it.
dsen cell: Hereinafter referred to as a K cell. ) 27 and has a shutter S _2.

The O radical port 31 introduces an oxygen gas, which is a raw material gas, into the electrodeless discharge tube.
O radicals generated by using 6 MHz) are jetted into the MBE chamber 1. The orifice 33 and the shutter S ₃ is provided for an O radical beam.

The N radical port 41 introduces a nitrogen gas as a raw material gas into the electrodeless discharge tube, and applies a high frequency (13.5).
N radicals generated by using 6 MHz) are jetted into the MBE chamber 1. Shutter S ₄ is provided with respect to the beam of the N radical.

The structure of the radical ports 31 and 41 is such that an induction coil is wound around a discharge tube provided in the outer shield tube.

In the chamber 1, there are provided a substrate holder 3 for holding a sapphire substrate S serving as a base for crystal growth, and a heater 3a for heating the substrate holder 3. The temperature of the sapphire substrate S can be measured by the thermocouple 5. The position of the substrate holder 3 can be moved by a manipulator 7 using bellows.

The chamber 1 includes a gun 51 of a reflection high energy electron diffraction device (RHEED device) and a screen 55 of the RHEED device provided for monitoring the grown crystal layer. Using the gun 51 of the RHEED device and the screen 55 of the RHEED device, the growth can be performed while monitoring the state of crystal growth (growth amount, quality of the grown crystal layer) in the MBE device A.

The temperature of crystal growth, the thickness of the crystal growth film, the degree of vacuum in the chamber, and the like are appropriately controlled by the controller C. Crystal growth by opening and closing the S ₄ as appropriate from the shutter S ₁ RF-
This is performed by the MBE method.

As a method for generating a radical source, RF is used. O radicals are generated by introducing O ₂ as a source gas into the electrodeless discharge tube using a high frequency of 13.56 MHz. For example, by blowing O radicals into the MBE chamber 1 in a high vacuum state, an O radical beam is generated. O radical beam and K
By simultaneously irradiating the sapphire substrate S with the Zn beam from the cell, a ZnO thin film can be grown. Similarly, when doping N as an impurity,
Irradiation with a radical beam may be performed.

Hereinafter, the step of growing ZnO on the substrate S will be described in detail. A predetermined pretreatment is performed on the sapphire substrate. First, the sapphire substrate is washed with an organic solvent. Next, phosphoric acid and sulfuric acid are mixed at a ratio of 1: 3, and the sapphire substrate is wet-treated for 30 minutes in a mixed solution heated to 110 ° C. Thereafter, the sapphire substrate is mounted on the substrate holder in the chamber, and the inside of the chamber is evacuated to a high vacuum of 10 ⁻¹⁰ Torr (1.33 × 10 ⁻⁸ Pa). After the chamber is brought into a high vacuum state, heat treatment is performed in a reducing gas, for example, hydrogen gas at a temperature higher than the subsequent growth temperature, for example, 1000 ° C. for about 30 minutes.

Next, the substrate temperature is lowered to a predetermined growth temperature, for example, 600 ° C., and the substrate is irradiated with a Zn beam and an O radical beam to start growing a ZnO crystal. A ZnO layer having a predetermined thickness is grown. In growing the MgZnO layer, the shutter S ₄ also drilled Mg beam also irradiated onto the substrate.

The ZnO crystal grown in the above growth step was evaluated by the CAICISS method.

FIG. 2 shows the signal intensity (vertical axis) of the ZnO film measured by the CAICISS method and the incident angle θ of He ions.
FIG. 6 is a diagram showing a relationship with the horizontal axis. FIG. 2 also shows a calculation result based on a simulation (theoretical calculation). The simulation is based on a three-dimensional two-atom three-time scattering model (Three dimensional tw
o-atom triple scattering
model) was used. The simulation result shown in FIG. 2 is a calculation result regarding the ZnO layer where the Zn polar plane is exposed.

FIG. 2 shows that the experimental results and the simulation results show good agreement. That is, it is considered that the ZnO layer grown under the above growth conditions is grown on the Zn polar plane. It is considered that this result can be extended not only to ZnO-based crystals but also to other II-VI group semiconductor crystals. By limiting the group II element to a system containing Zn, it is considered that the effects described below can be easily obtained.

When growing a ZnO crystal on a sapphire substrate, depending on the substrate processing conditions before growing the ZnO-based crystal, the ZnO crystal is grown on the O-polar plane or
You can decide whether to grow on polar faces. When the surface of the sapphire substrate is subjected to a heat treatment at a temperature higher than the growth temperature, specifically, at a temperature of 800 ° C. or higher in a reducing gas atmosphere, ZnO crystals grow on the Zn polar plane. When the surface of the sapphire substrate is heat-treated in an atmosphere other than the reducing gas, or even in the reducing gas, for example, 800 ° C.
When heat treatment is performed at a temperature lower than the following crystal growth temperature,
A ZnO crystal grows on the O-polar plane.

The substrate processing atmosphere may be an atmosphere containing plasma-like hydrogen or atomic hydrogen other than hydrogen gas, or a reducing gas atmosphere such as an NH ₃ gas atmosphere.
Further, as a substrate processing condition, an AlN buffer layer or a Mg ₃ N ₂ buffer layer is formed
Group I-VI semiconductor crystals could also be grown on the polar plane of the group II atoms, including Zn.

Next, an experiment for doping N as an impurity in the ZnO crystal layer was performed. The sapphire substrate was irradiated with N radicals generated using the N radical port 41 toward the sapphire substrate during the growth of the ZnO crystal layer, thereby doping N impurities.

The ZnO crystal grows on the O polar plane or Z
Two experiments were performed so as to grow on either the n-polar plane, and the characteristics of ZnO crystals grown on the O-polar plane and ZnO crystals grown on the Zn-polar plane were compared. As mentioned earlier, O
In order to grow on the polar plane, heat treatment was performed at 1000 ° C. for 30 minutes in a high vacuum before growing the ZnO crystal.

As a result of measuring the N impurity concentration by the impurity concentration analysis, it was found that the ZnO crystal grown on the O-polar surface and the ZnO crystal grown on the Zn-polar surface showed the N impurity concentration in the ZnO crystal grown on the Zn-polar surface. Was about two orders of magnitude higher. As the N impurity concentration in the ZnO crystal grown on the Zn polar plane, for example, a value on the order of 10 ¹⁹ cm ⁻³ is obtained.

The optical characteristics of the ZnO crystal grown on the Zn plane and the ZnO crystal grown on the O-polar plane when the impurity (N) is doped are compared.

FIG. 3 shows a ZnO crystal grown on a Zn polar plane and a ZnO crystal grown on an O polar plane on a sapphire substrate.
FIG. 9 is a diagram showing a comparison between PL characteristics when a crystal and a crystal are doped with N under the same conditions. An N-doped ZnO crystal grown on the Zn polar face by heat treatment of the sapphire substrate in a reducing gas, and a sapphire substrate was heat-treated at 1000 ° C. for 30 minutes in a high vacuum to grow on the O polar face before growing the ZnO crystal. The PL characteristics with the N-doped ZnO crystal were compared. The PL measurement was performed at a substrate temperature of 4.2K.

As shown in FIG. 3, the PL intensity of the N-doped ZnO crystal grown on the Zn-polar surface is about eight times higher than the PL intensity of the N-doped ZnO crystal grown on the O-polar surface. Understand. From this result, even when N is doped as an impurity, ZnO grown on the Zn polar plane
It was found that the crystal had better optical characteristics than the ZnO crystal grown on the O-polar plane. As mentioned above, it is believed that these results can be extended to other II-VI semiconductor crystals.

According to the experiment of the inventor, N was set to 10 ¹⁹ c
It has been found that when doping is performed to a high concentration on the order of m ^{−3, the} non-emission center increases due to the self-compensation effect, and the optical characteristics tend to deteriorate. Considering this point and the result of the PL intensity, the ZnO crystal grown on the Zn polar plane and the ZnO crystal grown on the O polar plane have a higher impurity (N) content than the ZnO crystal grown on the Zn polar plane. The activation rate is fairly good. In other words, it can be said that the ZnO crystal grown on the Zn polar plane has better optical characteristics and the impurity activation rate than the ZnO crystal grown on the O polar plane.

As described above, when the surface of the sapphire substrate is treated so that ZnO crystal grows on the Zn polar plane, and then the ZnO crystal is actually grown on the Zn polar plane, excellent optical characteristics can be obtained. It was found that ZnO crystals could be grown.

Next, a semiconductor crystal according to a second embodiment of the present invention will be described. In the present embodiment, a ZnO crystal is grown on a hexagonal SiC substrate. Si
As the C substrate, a substrate having a (0001) plane (+ C plane) as a main surface is used. An etching process is performed on the surface of the SiC substrate using predetermined conditions. Thereafter, the substrate is attached to the RF-MBE apparatus, and the substrate temperature is raised to a predetermined substrate temperature, for example, 800 ° C. Thereafter, the shutter S ₃ of the oxygen plasma gun 31
Open. At this time, the flow rate of oxygen was set to 3 sccm, and RF
The power is 300 W. Although the required processing time varies depending on the substrate temperature, for example, when the substrate temperature is 800 ° C., the processing time is preferably 30 minutes or more.

After terminating the oxygen treatment, the temperature of the SiC substrate is lowered to a predetermined temperature, for example, 600 ° C., and a ZnO crystal layer is grown. That is, the growth of the ZnO crystal is preferably performed at a temperature lower than the heat treatment temperature in the oxygen plasma atmosphere.

Using the above process, ZnO crystals grow on the Zn polar plane. By growing on the Zn-polar plane, the ZnO crystal exhibits good optical characteristics and a high activation rate, as in the case of the semiconductor growth techniques according to the first and second embodiments.

As the processing gas before the ZnO crystal growth,
At least one selected from the group consisting of oxygen gas, N ₂ O, NO _X and ozone may be selected and used. Heat treatment may be performed using atomic oxygen formed by cracking these oxidizing gases. On this occasion,
The oxidizing gas may be cracked using a method selected from an RF method, an ECR method, and a heat treatment method using heat of a filament or the like. After performing the above processing, Zn
When the O crystal is grown, the ZnO crystal can be grown on the Zn polar plane.

As described above, when the semiconductor growth technique according to the second embodiment of the present invention is used, Zn is deposited on the SiC substrate.
O-based crystals can be grown on the polar plane of Zn. Therefore, it is possible to grow a ZnO-based crystal having a small number of non-emission centers and excellent optical characteristics. In addition, the activation rate of impurities can be increased.

In the semiconductor crystal growth techniques according to the first and second embodiments, the case where a ZnO-based crystal is grown on a SiC substrate or a sapphire substrate has been described as an example. ZnO on (+ C plane)
If a crystal is grown, it can be grown on the Zn polar plane,
It is clear that the optical characteristics of the ZnO-based crystal layer can be improved.

As described above, as described above, Z
When growing the nO-based crystal, the pretreatment conditions for growing the ZnO-based crystal on the Zn polar plane differ depending on the type of the substrate to be used.
By selecting pretreatment conditions that allow the O-based crystal to grow, the ZnO-based crystal can actually be grown on the Zn polar plane.

Next, an optical semiconductor device according to a third embodiment of the present invention will be described with reference to FIG.

LED (Light Emitting)
The crystallinity of a semiconductor crystal material constituting an optical semiconductor device such as a diode (LD) or a laser diode (LD) has a significant effect on the electrical characteristics, optical characteristics, and reliability (device life) of the optical semiconductor device. . The better the crystallinity of the semiconductor crystal material constituting the optical semiconductor device, the better the optical / electrical characteristics and reliability of the optical semiconductor device.

First, on the starting substrate surface, ZnO
If a treatment for growing a system crystal is performed, and a ZnO-based crystal layer constituting the structure of the optical semiconductor device is grown on the Zn polar plane, an optical semiconductor device having good optical characteristics can be manufactured.

The optical semiconductor device C shown in FIG. 4 uses a sapphire substrate 51 as a starting substrate. The surface of the sapphire substrate 51 is subjected to a heat treatment at a temperature higher than the growth temperature in a reducing gas. Thereafter, when the ZnO-based crystal is grown by the RF-MBE method, the ZnO-based crystal grows on the Zn polar plane.

In this embodiment, the design of the LED
As a ZnO-based crystal, Z
Mg other than nO layer_xZn_1-xAn O layer was also grown. Mg_x
Zn_{1 -x}The O layer is provided separately in the RF-MBE apparatus shown in FIG.
In the process, a port for Mg is provided and the beam of Zn, O and Mg is
It can be grown by irradiating the plate.

The pressure in the chamber during crystal growth is 1 × 10 ⁻⁵ Torr (1.33 × 10 ⁻³ Pa) for all layers.

Hereinafter, examples of the growth temperature, film thickness, and growth material of each layer will be described.

First, after performing a pretreatment on the sapphire substrate 51 to make it a Zn polar plane, the growth temperature, for example, 600 ° C.
Down to

Note that N is used as the n-type dopant.

On the Mg _0.05 Zn _0.95 O buffer layer 53,
grown n-Mg _0.33 Zn _0.67 O cladding layer 55 is then grown Mg _0.05 Zn _0.95 O buffer layer 53. An n-ZnO cladding layer may be further formed as a cladding layer. Mg _0.05 Zn _0.95 O buffer layer 53 and n-Mg
_An n-ZnO cladding layer may be inserted between the _0.33 Zn _0.67 O cladding layer 55.

Next, the multiple quantum of MgZnO / ZnO
An active layer 61 having a well structure is grown. On the active layer 61
Next, a p-MgZnO cladding layer 63 is grown. p-
Mg_{0 .33}Zn_0.67P-ZnO core on the O cladding layer 63
A contact layer 65 is grown.

The laminated structure grown as described above is processed.

The active layer 61, the clad layer 63, and the clad layer 65 are processed into an island shape to form an island-shaped laminated structure SS1. A part of the surface of the n-type Mg _x Zn _{1 -x} O clad layer 65 is exposed.

The side wall of the island-shaped stacked structure SS 1 is covered with a side spacer insulating film 71. An opening 72 is formed above the side spacer insulating film 71, and the surface of the p-ZnO contact layer 65 is exposed from the opening 72.

The active layer 61 may be made of ZnCdO / ZnO or MgZnC in addition to the above-described multiple quantum well structure.
A multiple quantum well structure such as dO / MgZnCdO can also be used.

The active layer 61 is formed by combining the n-type cladding layer 55 with the p-type cladding layer 55.
A double hetero structure sandwiched between the mold cladding layers 63 may be formed. In that case, for example, the thickness of the active layer 61 is 10 to 100 nm. When a multiple quantum well structure is formed, well layers and barrier layers are formed alternately. In this case, the total thickness of one well layer and one barrier layer is 10 nm.
The following is preferred. However, the thickness of one well layer is 1
Preferably, it is thinner than the thickness of the barrier layer. It is preferable that one unit is composed of one well layer and one barrier layer, and this one unit is repeated for three to five periods.

A lower electrode 73 is formed in contact with the n-type ZnO cladding layer 55, and an upper electrode 75 having an opening 72 on the light receiving surface is formed on the p-type ZnO contact layer 65. Thus, a light emitting diode LED can be formed. In the light emitting diode LED, the ZnO-based crystal layer, in particular, the active layer 61 is grown on the Zn polar plane through the above-described steps, so that the number of non-light emitting centers is small. Compared with the same non-light-emission center amount, the doping amount of the impurity can be increased, so that, for example, the resistivity in the contact layer 65 can be reduced, and the contact resistance between the electrodes can be reduced.

Therefore, the optical characteristics of the LED can be improved. For example, the present invention is applicable to short-wavelength (UV to blue) LEDs and various indicators and displays using the same. Further, the present invention can be applied to a white LED and a lighting fixture using the same, various indicators, a display, and a backlight of each display.

In this embodiment, an example has been described in which an LED is manufactured as an optical semiconductor element.
In addition, it goes without saying that the optical characteristics can be improved even when a laser device or the like is formed.

In addition to the sapphire substrate, the above-described S
A similar ZnO-based optical semiconductor element can be formed on an iC substrate or a substrate having a ZnO (0001) plane (+ C plane) as a main surface.

Further, the RF-MBE method has been exemplified as a method for growing the ZnO-based crystal.
For example, a gas source MBE method may be used. Or M
An OCVD method may be used.

In particular, in the growth technique using the MOCVD method, a step of performing a substrate surface treatment in an H ₂ atmosphere and then growing a semiconductor crystal of II-VI group or the like is generally used. Therefore, it is easy to continuously perform the substrate surface treatment step and the crystal growth step in one MOCVD apparatus. That is, a technique of performing a pretreatment of a substrate by using the MOCVD method and then growing a II-VI group semiconductor crystal is included in the present invention and can be said to be one of the leading techniques among them.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these embodiments. Various conditions for crystal growth and other process parameters can also be selected. It will be obvious to those skilled in the art that various changes, improvements, combinations, and the like can be made.

[0067]

According to the present invention, a ZnO-based crystal having excellent optical characteristics can be grown. Further, II-
The doping amount of impurities into the group VI semiconductor crystal can be increased. Using these II-VI semiconductor crystals, an optical semiconductor device having excellent optical characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an RF-MBE apparatus used for a method for growing a ZnO-based crystal according to a first embodiment of the present invention.

FIG. 2 shows the signal intensity (vertical axis) of the ZnO crystal measured by the CAICISS method and the incident angle θ of He ions (horizontal axis).
6 is a spectrum graph showing a relationship with. FIG. 2 also shows the simulation results.

FIG. 3 is a spectrum graph showing the results of PL measurement at 4.2 K and a ZnO crystal grown on a Zn polar plane and a ZnO crystal grown on an O polar plane.

FIG. 4 is a cross-sectional view illustrating a structure of an LED device including a pn junction diode using a ZnO-based crystal according to a third embodiment of the present invention.

[Explanation of symbols]

A RF-MBE apparatus P Vacuum pump 1 Chamber 3 Substrate holder 3a Heater 5 Thermocouple 7 Manipulator 11 Zn port 11 21 Mg port 31 O radical port 41 N radical port 17, 27, 47 Knudsen cell 33 Orifice S substrate 51 Sapphire substrate 53 Mg _0.05 Zn _0.95 O buffer layer 55 n-Mg _0.33 Zn _0.67 O clad layer 61 active layer 63 p-MgZnO clad layer 65 p-ZnO contact layer SS1 laminated structure 71 side spacer insulating film 72 opening 73 lower electrode 75 upper electrode

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takafumi Yao 2-1-1 Katahira, Aoba-ku, Sendai-shi, Miyagi F-term in the Institute for Materials Research, Tohoku University 4G077 AA03 AB02 BB07 DA05 DB08 ED06 EE01 5F041 AA40 AA43 CA04 CA05 CA41 CA65 CA66 CA73 5F045 AA04 AB22 AC11 AC15 AD10 AD12 AF02 AF09 AF13 CA11 DA53 DA55 EB02 HA06 5F073 AA74 CA22 DA05 DA06 DA16

Claims (21)

[Claims] 1. A method for growing a II-VI group semiconductor crystal on a substrate, comprising: (a) performing a predetermined pretreatment on the substrate surface; and (b) II-VI group on the substrate surface. Growing the group III semiconductor crystal on the polar plane of the group II atom. 2. The method according to claim 1, wherein the step (a) includes a step of performing a substrate treatment in the step (b) such that the II-VI group semiconductor crystal grows on the polar plane of the group II atom. A method for growing a semiconductor crystal. 3. The method of claim 2, wherein the group II atom comprises Zn,
3. The method for growing a semiconductor crystal according to claim 1, wherein the group atoms include O. 4. The method of growing a semiconductor crystal according to claim 1, wherein the step (a) includes a step of (a-1) heat-treating the sapphire substrate in a reducing gas atmosphere. . 5. The method of growing a semiconductor crystal according to claim 4, wherein the step (a-1) includes a step of heat-treating the sapphire substrate at a temperature of 850 ° C. or more in a reducing gas. 6. The method of growing a semiconductor crystal according to claim 4, wherein the step (a-1) includes a step of heat-treating the sapphire substrate in a hydrogen gas atmosphere. 7. The method of growing a semiconductor crystal according to claim 6, wherein said step (a-1) includes a step of heat-treating the sapphire substrate in an atomic hydrogen atmosphere formed by cracking hydrogen gas. 8. The semiconductor according to claim 4, wherein a temperature at which the sapphire substrate is heat-treated is higher than a crystal growth temperature in the step of growing the II-VI group semiconductor crystal. Crystal growth method. 9. A method for growing a II-VI group semiconductor crystal on a SiC substrate, comprising: (a) performing a predetermined pre-treatment on the surface of the SiC substrate; and (b) forming a pre-treatment on the surface of the SiC substrate. Growing a group II-VI semiconductor crystal on the polar plane of group II atoms. 10. The method according to claim 9, wherein the step (a) includes a step of performing a substrate treatment such that the II-VI group semiconductor crystal grows on the polar plane of the group II atom in the step (b). A method for growing a semiconductor crystal. 11. The method of claim 11, wherein the group II atom comprises Zn,
The method for growing a semiconductor crystal according to claim 9, wherein the group I atom contains O. 12. The semiconductor crystal growth according to claim 9, wherein said step (a) includes a step of (a-1) heat-treating said SiC substrate in an oxidizing gas atmosphere. Method. 13. The step (a-1) comprises: (a-1-1) at least one kind selected from an oxidizing gas group consisting of oxygen, N ₂ O, NO _x and ozone. The method of growing a semiconductor crystal according to claim 12, further comprising a step of performing a heat treatment in a gas atmosphere. 14. A heat treatment temperature for the SiC substrate,
The method of growing a semiconductor crystal according to any one of claims 9 to 13, wherein the temperature is higher than a crystal growth temperature in the growing step of the II-VI group semiconductor crystal. 15. The (a-1-1) step is at least one kind selected from the group consisting of an RF plasma processing method, an ECR plasma processing method, and a heat treatment method using heat generated from a filament. 15. The method for growing a semiconductor crystal according to claim 13, further comprising a step of performing a heat treatment using atomic oxygen formed by cracking the oxidizing gas using a method. 16. A semiconductor comprising: a) preparing a ZnO single crystal substrate having (0001) (+ C plane) as a main surface; and (b) growing a II-VI group semiconductor crystal on the main surface. Crystal growth method. 17. The method according to claim 17, wherein the step (b) comprises:
The method for growing a semiconductor crystal according to any one of claims 1 to 16, further comprising a step of growing the II-VI group semiconductor crystal by an RF-MBE method supplied by plasma excited by the method. 18. An optical semiconductor device comprising: a substrate; and an active layer including a II-VI group semiconductor crystal layer grown on a polar plane of a group II atom on the substrate. 19. A substrate, a first cladding layer formed on the substrate and including a II-VI group semiconductor crystal layer, the first cladding layer having a first conductivity type.
An active layer formed on the first cladding layer, and a second cladding layer formed on the active layer and having a second conductivity type opposite to the first conductivity type, At least one of the semiconductor crystal layers constituting the stack is II
An optical semiconductor device comprising: a stack grown on a group polarity surface; and first and second electrodes electrically connected to the first cladding layer and the second cladding layer, respectively. 20. The II-VI group semiconductor crystal layer,
The optical semiconductor device according to claim 18, wherein the optical semiconductor device is an nO-based semiconductor crystal layer. 21. The step (b) is performed by MBE or MO
17. The method of growing a semiconductor crystal according to claim 1, further comprising a step of growing a II-VI group semiconductor crystal using a CVD method.