JP2002261017A - Method of growing compound semiconductor crystal and optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of growing a compound semiconductor crystal, with which an n-type ZnTh-family substance doped at up to a high concentration is grown and a pn junction in a ZnTh substance is easily formed, and an optical semiconductor device thereby. SOLUTION: An n-type ZnTh layer 2 doped at a high concentration of 1×10<17> cm<-3> or higher is grown on a substrate 1 by using molecular-beam epitaxy for the crystal growth method, wherein Al is used for the dopant, and growth condition for the ZnTh is optimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for growing a compound semiconductor crystal and an optical semiconductor device.

[0002]

2. Description of the Related Art ZnTe is a semiconductor of direct transition having a band gap in a green region, and is a substance suitable for manufacturing optical devices such as a light emitting device, a light detecting device, a light modulating device and the like ranging from red to blue.

[0003] As a conventional prior art, there is one disclosed below. (1) V. N. J. Iodko et al. Cryst. Gr
owth 184/185 (1998) 1170-11
74. (2) H. Ogawa et al., Jpn. J. Appl. P
hys. 33, L980 (1994). (3) M.P. C. Phillips et al., Appl. Ph
ys. Lett. (4) I. W. Tao et al., Appl. Phys. Le
tt. 1848 (1994). (5) T. L. Larson, C.A. F. Varott
o, and D. A. Stevenson, J .; App
l. Phys, 43 (1972) 172.

[0004]

(A) The above document (1)
According to the report, in the formation of n-type ZnTe by bulk crystal, doping of about 10 ¹⁹ cm ⁻³ is achieved by diffusion of Al, but this method does not eliminate the formation of a heterojunction indispensable for forming an optical element. It is possible and practical optical elements cannot be developed.

(B) According to the above reference (2), regarding n-type ZnTe growth by the thin film growth method, the highest electron concentration achieved so far is the n-type ZnTe grown by the metalorganic vapor phase method. It is growth. That is, Al doping using Al alkyl is attempted, and the electron concentration is 4 × 1
0 ¹⁷ cm ^-3 was achieved. However, this concentration causes problems such as formation of an ohmic electrode, and is insufficient for practical optical device fabrication. Furthermore, at this maximum electron concentration, the optical properties are significantly degraded, making device application of thin films of this concentration substantially difficult.

(C) According to the above reference (3), although growth of n-type ZnTe by molecular beam epitaxy has been attempted, the electron concentration remains low. That is, with respect to the doping of Al, the resistance is high in the as-grown state, and the electron concentration attains only 9 × 10 ¹⁵ cm ⁻³ by annealing. At this concentration, of course, it cannot be applied to optical devices. The report does not specify growth conditions.

(D) According to the above reference (4), chlorine doping was attempted for the growth of n-type ZnTe by molecular beam epitaxy. However, the electron concentration is 3 × 10
It remains at ¹⁶ cm ^-3 , which is also insufficient for developing a practical optical device.

As described above, the only example of a high-concentration n-type ZnTe of 5 × 10 ¹⁷ cm ⁻³ or more reported so far is the formation of a high-concentration n-type ZnTe by diffusion in bulk. . From the viewpoint of practical device development, it is essential to establish a growth technique for high-concentration n-type ZnTe using a thin film technique capable of forming a heterojunction, but unfortunately, conventional thin film techniques cannot meet this demand. Was. For example, for a light emitting diode, 2 × 10
A high-quality thin film with an electron concentration of about ¹⁷ cm ^-3 is required, and 10 ¹⁸ c
A high concentration layer of m ^-3 or more is required. It should be noted that the barrier layer needs to show good optical properties, but the MOCVD thin films reported so far are not at the level of device application. The demand for this thin film becomes more severe in a practical level semiconductor laser, and the electron concentration of the barrier layer is required to be about 5 × 10 ¹⁷ cm ⁻³ , and that of the electrode contact layer is 2 × 10 ¹⁸ cm ^−3.
-3 is required. For this reason, it has not been applied to a light emitting element, a light detecting element, a light modulating element, or the like using a ZnTe-based material.

Further, formation of a pn junction is indispensable for fabricating the above-mentioned optical element.
It has been believed that molds are easy to grow, but n-type is difficult, especially high concentration n-type.

[0010] In view of the above situation, the present invention provides a high concentration of n
An object of the present invention is to provide a compound semiconductor crystal growth method and an optical semiconductor device that can grow a type ZnTe-based material and can easily form a pn junction of the ZnTe-based material.

[0011]

According to the present invention, there is provided a method for growing a compound semiconductor in which a high concentration resistance n-type ZnTe crystal is grown by doping an n-type impurity in ZnTe. In the above, a high concentration n-type ZnTe of 1 × 10 ¹⁷ cm ⁻³ or more is grown by growing a crystal using molecular beam epitaxy, using Al as an impurity, and optimizing the ZnTe growth conditions. It is characterized by the following.

[2] The method of growing a compound semiconductor crystal according to the above [1], wherein a ZnTe substrate is used.

[3] The method for growing a compound semiconductor crystal according to the above [1] or [2], wherein Zn and Te are used as growth raw materials.

[4] In the method for growing a compound semiconductor crystal according to the above [1] or [2], ZnT may be used as a growth material.
e and Te are used.

[5] The method for growing a compound semiconductor crystal according to the above [1] or [2], wherein ZnT is used as a growth material.
It is characterized by using e and Zn.

[6] In the method for growing a compound semiconductor crystal according to [1] or [2], ZnT may be used as a growth material.
It is characterized by using e, Zn and Te.

[7] The above [1], [2], [3],
[4] The method for growing a compound semiconductor crystal according to [5] or [6], wherein the substrate temperature is in a range of 220 ° C to 350 ° C.

[8] The above [1], [2], [3],
In the method for crystal growth of a compound semiconductor according to [4], [5] or [6], the molecular beam intensity ratio between Zn and Te is 1: 1.
2-1 to 5.0.

[0019]

[9] The above [1], [2], [3],
[4] The method for growing a compound semiconductor crystal according to [5] or [6], wherein the growth rate is in the range of 0.2 to 2.0 microns per hour.

[10] The above [1], [2], [3],
[4] The method for growing a compound semiconductor crystal according to [5] or [6], wherein the temperature of Al is set to 700 to 900 ° C.

[11] In an optical semiconductor device, a substrate;
And an Al-doped n-type ZnTe layer formed by molecular beam epitaxy formed on the substrate.

[12] In an optical semiconductor device, a substrate;
A buffer layer formed on the substrate and an n-type ZnTe layer doped with Al and formed on the buffer layer by molecular beam epitaxy are provided.

[13] An optical semiconductor device is characterized by comprising a semiconductor layer and an Al-doped n-type ZnTe layer formed on the semiconductor layer by molecular beam epitaxy.

[14] In an optical semiconductor device, a substrate;
It is characterized by including an Al-doped n-type ZnTe layer formed on the substrate by molecular beam epitaxy, and a semiconductor layer or a metal layer formed on the n-type ZnTe layer.

[15] In an optical semiconductor device, a semiconductor layer, an Al-doped n-type ZnTe layer formed on the semiconductor layer by a molecular beam epitaxy method,
A semiconductor layer or a metal layer formed on the n-type ZnTe layer.

[16] The above [11], [12] or [1]
4] In the optical semiconductor device described in [4], the substrate is GaSb.
It is a substrate, a semiconductor substrate such as an InAs substrate or a GaAs substrate, an insulating substrate such as sapphire or MgO, or a ZnTe substrate.

[17] In the optical semiconductor device according to the above [12], the buffer layer is made of Zn on a ZnTe substrate.
Te epitaxy layer, GaSb substrate for GaSb epitaxy layer, ZnTe epitaxy layer or ZnTe epitaxy layer on GaSb epitaxy layer, InA substrate for InA
s epitaxy layer, ZnTe epitaxy layer on ZnTe epitaxy layer or GaSb epitaxy layer, GaAs epitaxy layer, ZnSe epitaxy layer on GaAs substrate, Z
Zn on nTe epitaxy layer, GaAs epitaxy layer
ZnT on Se epitaxy layer, GaAs epitaxy layer
ZnS on e-epitaxy layer or GaAs epitaxy layer
An e-epitaxy layer and a ZnTe epitaxy layer, a sapphire substrate, and a MgO substrate include a ZnTe layer.

[0028]

Embodiments of the present invention will be described below in detail.

FIG. 1 is a schematic view of a compound semiconductor device according to a first embodiment of the present invention.

In this figure, reference numeral 1 denotes a substrate, and 2 denotes an A formed on the substrate 1 by a molecular beam epitaxy method.
1 is a heterostructure including a ZnTe layer doped with l, for example, ZnTe / ZnMgSeTe / ZnTe / ZnC
It is a dTe / ZnTe / ZnMgSeTe hetero quantum well structure. FIG. 2 schematically shows a hetero-band structure of this structure, in which electrons are converted to ZnTe / ZnCdTe.
The hole is confined at the hetero interface and the hole is ZnMgSeTe / Z
It can be confined at the nTe interface. Also, where
Instead of ZnTe / ZnCdTe / ZnTe, ZnS
An eTe layer or a ZnTe / ZnSeTe / ZnTe hetero layer can also be used.

Reference numeral 3 denotes a back contact layer (-), 4 denotes a metal electrode (+), and 5 denotes a wire bond. Here, the substrate 1 is a GaSb substrate, an InAs substrate, or a GaAs substrate.
A semiconductor substrate such as a substrate, an insulating substrate such as sapphire or MgO, or a ZnTe substrate is used.

FIG. 3 is a schematic view of a compound semiconductor device according to a second embodiment of the present invention.

In this figure, 11 is a substrate, 12 is a buffer layer formed on the substrate 11, and 13 is an Al formed on the buffer layer 12 by the molecular beam epitaxy method shown in the first embodiment. Doped Zn
Heterostructure including a Te layer, 14 a back contact layer, 1
5 is a metal electrode and 16 is a wire bond.

In this embodiment, an Al-doped Z formed on a substrate 11 by molecular beam epitaxy is used.
A buffer layer 12 is grown to alleviate irregularities between the heterostructure 13 including the nTe layer and the substrate 11. Al formed on the buffer layer 12 by molecular beam epitaxy
A heterostructure 13 including a ZnTe layer doped with is provided. Here, as the substrate 11, a GaSb substrate, In
Semiconductor substrates such as As substrates and GaAs substrates, sapphire,
An insulating substrate such as MgO or a ZnTe substrate is used. The buffer layer 12 is a ZnTe epitaxy layer for a ZnTe substrate, a GaSb epitaxy layer for a GaSb substrate,
An InAs substrate uses an InAs epitaxy layer, and a GaAs substrate uses a GaAs epitaxy layer. In the case of a sapphire substrate or an MgO substrate, a ZnTe layer is used.

FIG. 4 is a schematic view of an optical semiconductor device showing a third embodiment of the present invention.

In this figure, 21 is a semiconductor layer, 22 is a heterostructure including an Al-doped n-type ZnTe layer formed on the semiconductor layer 21 by the molecular beam epitaxy method as in the first embodiment, 23 is a back contact layer, 24 is a metal electrode, and 25 is a wire bond.

This embodiment is an example in which a heterostructure 22 including an Al-doped n-type ZnTe layer formed by molecular beam epitaxy on a semiconductor layer 21 other than those described above.

FIG. 5 is a schematic view of an optical semiconductor device showing a fourth embodiment of the present invention.

In this figure, reference numeral 31 denotes a substrate, and 32 denotes an Al-doped n-type ZnTe formed on the substrate 31 by the same method as in the first embodiment formed by molecular beam epitaxy.
A heterostructure including layers, 33 is a semiconductor layer or a metal layer formed on the n-type ZnTe layer 32, 34 is a back contact layer, 35 is a metal electrode, and 36 is a wire bond.

In this embodiment, a semiconductor layer or a metal layer 33 is formed on a heterostructure 32 including an Al-doped n-type ZnTe layer formed on a substrate 31 and formed by molecular beam epitaxy.

FIG. 6 is a schematic view of an optical semiconductor device showing a fifth embodiment of the present invention.

In this figure, reference numeral 41 denotes a semiconductor layer; 42, a heterostructure including an Al-doped n-type ZnTe layer formed by molecular beam epitaxy as in the first embodiment; 43, a semiconductor layer or a metal layer; Is a back contact layer, 45 is a metal electrode, and 46 is a wire bond.

In this embodiment, an example in which a heterostructure 42 including an Al-doped n-type ZnTe layer formed by molecular beam epitaxy on a semiconductor layer 41 and a semiconductor layer or a metal layer 43 is further stacked. It is.

The present invention can be applied not only to the growth of high-concentration n-type ZnTe but also to the formation of an n-type layer of a II-VI compound mixed crystal semiconductor containing Zn and Te.
Therefore, ZnTe or always containing Zn and Te II
The present invention can also be applied to a light emitting element, a light detecting element, and a light modulating element using a group VI compound mixed crystal semiconductor.

According to the present invention, a high-concentration n-type ZnTe layer can be grown.

FIG. 7 is a diagram showing the relationship between the substrate temperature and the electron concentration of the compound semiconductor device according to the embodiment of the present invention.

In this embodiment, the Al cell temperature is 860 ° C.
And the molecular beam intensity ratio of Te: Zn is 1: 1.5 to 1: 5.
Was changed within the range. Growth rate 0.2-0.6μ / h
m.

An example of the measurement of the dependence of the electron concentration of the n-type ZnTe of the present invention on the Al cell temperature will be described. The growth conditions were a substrate temperature of 300 ° C., and Zn and Te were used as growth raw materials. The substrate was a ZnTe substrate, a low-temperature buffer layer was provided on the substrate, and an Al-doped layer was grown thereon. In this example, an n-type ZnTe crystal having a hole concentration of 1 × 10 ¹⁷ to 4 × 10 ¹⁸ cm ⁻³ is obtained.

As a result, a high-quality ZnTe-based light emitting element, light detecting element, and light modulating element can be realized.

FIG. 8 is a diagram showing the characteristics of the electron concentration with respect to the molecular beam intensity ratio of the compound semiconductor device according to the embodiment of the present invention.

In this embodiment, the Al cell temperature is 860 ° C.
Substrate temperature 300 ° C, growth rate 0.2-0.6μ / h
m.

FIG. 9 is a graph showing the characteristics of the electron concentration with respect to the Al cell temperature of the compound semiconductor device according to the embodiment of the present invention.

In this example, the substrate temperature is 300 ° C., and Te:
The Zn flux ratio is 1: 1.7 to 1: 4, and the growth rate is 0.4 μm / hour.

FIG. 10 is a graph showing the characteristics of the electron concentration with respect to the growth rate of the compound semiconductor device according to the embodiment of the present invention.

In this example, the substrate temperature is 300 ° C., the Al cell temperature is 860 ° C., and the molecular beam intensity ratio of Te: Zn is 1: 1.
7 to 1: 3.

[Experimental Example 1] Next, A was added to the n-type ZnTe layer grown on the ZnTe substrate by molecular beam epitaxy.
An experimental example of l doping is reported.

Here, the MBE of the solid source gives
A ZnTe: Al layer was grown on a p-ZnTe (001) substrate. The growth conditions for the ZnTe: Al layer were determined based on homoepitaxy conditions. The growth rate and growth temperature were fixed at 0.4 μm / h and 300 ° C., respectively.

The VI / II ratio was controlled to be about 2, that is, rich in Te. Al was used as a dopant source,
It was deposited by a Knudsen cell. In this experiment, Al
The cell temperature was varied from 700 ° C to 860 ° C.

Under the above growth conditions, the surface remained atomically smooth during growth. The thickness of the thin film is RH
EED intensity vibration (intensity oscilla)
1 μm. In addition, measurements using high-resolution triaxial X-ray diffraction were performed to numerically express the structural characteristics. The carrier concentration was measured by a measurement method using the Hall effect in a van der Pauw configuration using In as the ohmic junction electrode. When performing photoluminescence (PL) measurement, a He-Cd (325 nm) laser and an Ar ⁺ ion laser (488 nm) were used as excitation light sources.

Hereinafter, the results of the experiment will be described with reference to the drawings.

FIG. 11 shows doped ZnTe: Al
It is a figure which shows the result of having scanned the layer by (004) (omega) -2 (theta) X-ray diffraction (XRD), and an interference fringe is observed. Also, Zn
The Te: Al (T _Al : 800 ° C.) layer shows different diffraction peaks at low diffraction angles. This is due to the reduced lattice (la
This indicates that the T.sub.taction has occurred. Further, the full width at half maximum (FWHM) at the peak of ZnTe: Al is as narrow as 24 arcsecs, indicating that the ZnTe: Al layer has a structurally high quality.

In this figure, the observed lattice reduction can be explained in terms of Vegard's law, in which the lattice constant changes linearly with the Al mixed as an alternative. This relational expression is as follows.

Δa⊥ = (4 / √3) [(Δr _Zn Al _Zn +
Δr _Te Al _Te ) / (1.759 × 10 ²² )] Here, Δr _zn = −0.05 ° is the difference between the covalent valence radii of Al and Zn, and Δr _Te = −0.06 ° is the difference between Al and Te.
_Where Al _zn is the atomic concentration of Al at the Zn site and Al _Te is the atomic concentration of Al at the Te site. 1.759 × 10 ²² is the unit volume (un
It is the number of Zn (Te) atom sites in (it volume).

Using this equation, it can be calculated that the Al concentration is 3 × 10 ¹⁹ cm ^-3 , assuming that all Al atoms occupy alternative sites at the ratio Al _zn = 0.33 Al _Te. . This value is based on Zn grown under the same conditions.
It is considered that this substantially agrees with the electron concentration of the Se: Al layer (-32 × 10 ¹⁹ cm ⁻³ ).

Next, using In as the ohmic junction electrode, the carrier concentration was measured at room temperature by the van der Pauw method. To improve ohmic properties, a thin ZnSe: Al layer (（5 nm) was deposited on the Al-doped ZnTe layer. Typical resistivity is 10 ^-1 Ω.
cm. It was below.

FIG. 12 plots electron mobilities for a series of samples as a function of electron concentration. Here, ■ is obtained from the result of the n-type ZnTe: Al layer grown on ZnTe by MOCVD. The ZnTe: Al layer grown at an Al cell temperature of 800 ° C.
N _d = 8 × 10 ¹⁷ c at a carrier mobility of 9 cm ² / Vs
m- ³ . The highest carrier concentrations were obtained from samples grown at an Al cell temperature of 860 ° C. At this time, carrier concentration, while increases to ^{_{N d = 4 × 10 18 cm}} -3, the carrier mobility is reduced to 45cm ² / Vs.

In general compound semiconductors, the main scattering mechanism at room temperature is polar optical phonon scattering (po
lar-optical phonon squatte
ring) and ionized impurity scattering. The latter is particularly important for heavily doped semiconductors, while the former has nothing to do with the carrier concentration at room temperature. In the results obtained in this experiment, the mobility changes slowly in the low carrier concentration region (<5 × 10 ¹⁷ cm ⁻³ ). However, in a higher carrier concentration region, the concentration decreases with a fast movement. This is because polar-optical photon scattering (polar-optical scattering) occurs in a low carrier concentration region.
Only phonon scattering is dominant, suggesting that the scattering mechanism then changes to ionized impurity scattering. This agrees very well with the theoretical calculation of the carrier transport mechanism in n-type ZnTe.

It should be noted that the electron concentration obtainable from the n-type ZnTe layer shows completely different results depending on the impurities and the growth method. The ZnTe: Al layer grown by MOCVD on ZnTe was reported to have a concentration of 4 × 10 ¹⁷ cm ⁻³ and a mobility of 150 cm ² / Vs. on the other hand,
The n-type ZnTe: Cl layer grown by MBE on GaAs has an electron concentration of 3 × 10 ¹⁶ cm ⁻³ , indicating that it is preferable to select Al over Cl as the chemical species of the n-type dopant.

In this experiment, ZE grown by MBE was used.
The nTe: Al layer has a higher electron concentration and mobility than the MOCVD grown layer. To understand this difference, the definition of the compensation rate, ie, θ = (N _a ⁻ / N _d ⁺ )
, The compensation rates of these layers were estimated. here,
N _a ^- the total concentration of all residual acceptor unintended,
N _d ⁺ corresponds to the concentration of the ionized donor. The compensation rate θ was obtained from a calculated value obtained from the relationship between the carrier concentration and the carrier mobility as a function of the compensation rate. N _d = 4 × 10 ¹⁷
When the compensation rate of the ZnTe: Al layer grown by MOCVD at cm ⁻³ is calculated, θ = 0.94. This is a value obtained from a sample of similar concentration, θ = 0.85, N _d = 8.
It is larger than × 10 ¹⁷ cm ⁻³ . Despite limited detailed information, it is the growth temperature (MOCVD layer grown at 380-420 ° C.) that, based on the available data, a distinct difference between the samples is observed.

FIG. 13 is a graph showing the PL spectrum at a low temperature. FIG. 13 (a) is a graph showing a case without doping, and FIG. 13 (b) is a graph showing a case with a ZnTe: Al layer (T _Al : 700 ° C.). 13 (c) shows a ZnTe: Al layer (T _Al : 800)
° C). The undoped layer shows strong band edge emission with free exciton (X) emission.
The release at the deep level is almost negligible, suggesting high crystal quality.

However, the luminescence intensity of the Al-doped layer is increased by mixing Al as compared to the undoped layer. ZnTe: Al layer (T _Al : 7
The low temperature (00 ° C.) PL spectrum shows a free exciton (2.381 eV), a few bound exciton lines, a donor-acceptor pair (DAP) line, a deep emission (d
eep level emission). Among them, the relative peak intensity has a peak at 2.367 eV as compared with the case of the free exciton line, and shows an overwhelming increase due to Al mixing. Therefore, it can be specified as a donor-bound exciton line related to the Al donor. The exciton binding energy of this line can be estimated to be 14 meV, which indicates that Hayne's
Impurity binding energy ~ 140m due to s rule
eV.

On the other hand, the activation energy of the hydrogen donor was assumed to be 18.3 meV. 2.376 eV and 2.
The peak at 342 eV is considered to be for the acceptor-bound exciton line, as compared to the PL spectrum of the undoped layer. As the doping level increases, NB reaches a maximum at T _Al = 725 ° C.
E emission intensity increases. Deep level emission also increases as doping levels increase. This is probably the most major defect syndrome in Al-doped ZnTe bulk crystals in (5) above, V _Zn -A
It is thought to be due to the formation of multiple defects such as _lZn .

The DAP emission near 2.318 eV and the LO-phonon replica of the DAP line
It shows the meV energy difference, which is the L
It corresponds to the O-phonon energy. The line width of DAP emission is wide due to the various separation distances between ionized impurities. As shown in FIG. 14, the power dependency of the DAP line is examined using an Ar ⁺ laser 488 nm line. When the pumping power increased, the normal distance between impurities was shortened, so that the peak position of DAP shifted to a higher energy side. This indicates that the blue shift is 7 meV.

[Experimental Example 2] An example of manufacturing a light emitting device using Al doping will be described.

FIG. 15 schematically shows the structure of a light emitting diode manufactured by the molecular beam epitaxy method of the present invention.

In this figure, reference numeral 51 denotes p-type ZnTe: P
The layer 52 is a p-type ZnTe: N layer (16 nm) (this 51
And 52 function as LT buffer layers) and 53 is H
P-type ZnTe: N layer (104 n
m) and 54 are p-type ZnMgSe as a p-type grading layer
Te: N (312 nm), 55 is a non-doped ZnTe / ZnCdTe quantum well layer as an active layer, 56 is an n-type ZnMgSeTe: Al (312
nm), 57 is n-type ZnTe (8 nm), 58 is n-type Z
nSe (8 nm) (these 57 and 58 function as LT buffer layers), 59 is a p-type metal electrode, and 60 is an n-type metal electrode.

In this structure, p-ZnTe is used as a substrate, and p-Zn doped with nitrogen is used as a buffer layer.
Te is used. Also, ZnT as a p-cladding layer
p-ZnMgS doped with nitrogen lattice matched to e
An eTe layer is used. Further, a quantum well layer made of undoped ZnTe / ZnCdTe is used as the active layer. n- doped with Al as n-cladding layer
Using an ZnMgSeTe layer, an n-ZnTe layer doped with Al as an n-electrode contact layer and an n-ZnSn
A stack of layers is used.

FIG. 16 shows an emission spectrum obtained by this light emitting diode, which is used for an active layer. ZnCdTe
An example in which the Cd concentration of the layer is 15% and 30% is shown. As shown in FIG.
m, emission at 607 nm was observed. When the Cd composition is 12%, pure green laser oscillation at 553 nm is obtained.

The present invention is not limited to the above embodiment, but various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0080]

As described above in detail, according to the present invention, by optimizing the growth conditions of ZnTe, a high-quality and high-concentration n-type ZnT of 1 × 10 ¹⁷ cm ⁻³ or more can be obtained.
e, which can be applied to optical devices such as a light emitting device, a photodetector, and a light modulator at a practical level.

[Brief description of the drawings]

FIG. 1 is a schematic view of a compound semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a hetero band structure of the compound semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a compound semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a schematic view of an optical semiconductor device showing a third embodiment of the present invention.

FIG. 5 is a schematic view of an optical semiconductor device showing a fourth embodiment of the present invention.

FIG. 6 is a schematic view of an optical semiconductor device showing a fifth embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between an electron concentration and a substrate temperature in a compound semiconductor device according to an example of the present invention.

FIG. 8 is a diagram showing characteristics of an electron concentration with respect to a molecular beam intensity ratio of a compound semiconductor device according to an example of the present invention.

FIG. 9 shows an Al of a compound semiconductor device according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating characteristics of electron concentration with respect to cell temperature.

FIG. 10 is a graph showing characteristics of electron concentration with respect to a growth rate of a compound semiconductor device according to an example of the present invention.

FIG. 11 is a diagram showing the results of high-resolution X-ray diffraction measurement.

FIG. 12 is a diagram showing carrier concentration and mobility of a ZnTe: Al layer.

FIG. 13 is a diagram showing a low-temperature PL spectrum.

FIG. 14: DAP of ZnTe: Al (T _Al : 700 ° C.)
FIG. 4 is a diagram showing the excitation power dependence of the emission band.

FIG. 15 is a schematic view illustrating a structure of a light emitting diode manufactured by a molecular beam epitaxy method of the present invention.

16 is a diagram showing an emission spectrum obtained by the light emitting diode shown in FIG.

[Explanation of symbols]

1,11,31 substrate 2,13,22,32,42 heterostructure including Al-doped ZnTe layer formed by molecular beam epitaxy 3,14,23,34,44 back contact layer (-) 4,15 , 24, 35, 45 Metal electrode (+) 5, 16, 25, 36, 46 Wire bond 12 Buffer layer 21, 41 Semiconductor layer 33, 43 Semiconductor layer or metal layer 51 P-type ZnTe: P layer 52 p-type ZnTe: N layer (16 nm) 53 p-type ZnTe: N layer (104 nm) 54 p-type ZnMgSeTe: N (312 nm) (p
Type non-doped ZnTe / ZnCdTe quantum well layer (active layer) 56 n-type ZnMgSeTe: Al (312 nm)
(N-type grad layer) 57 n-type ZnTe (8 nm) 58 n-type ZnSe (8 nm) 59 p-type metal electrode 60 n-type metal electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G077 AA03 AB01 DA05 EA02 EB01 ED06 EF02 EF03 SC02 5F041 AA40 CA05 CA34 CA35 CA41 CA46 CA55 CA57 CA66 5F103 AA04 DD30 HH03 HH04 JJ03 KK10 LL02 LL04 LL17 NN05 NN01

Claims (17)

[Claims] 1. A compound semiconductor crystal growth method for growing a high-concentration low-resistance n-type ZnTe crystal by doping an n-type impurity into ZnTe, wherein the crystal is grown using molecular beam epitaxy and Al is used as an impurity. By optimizing the growth conditions of ZnTe, high-concentration n-type Zn of 1 × 10 ¹⁷ cm ⁻³ or more can be obtained.
A method for growing a crystal of a compound semiconductor, comprising growing Te. 2. The method of growing a compound semiconductor crystal according to claim 1, wherein a ZnTe substrate is used. 3. The method of growing a compound semiconductor crystal according to claim 1, wherein Zn and Te are used as growth raw materials. 4. The method of growing a compound semiconductor crystal according to claim 1, wherein ZnTe and Te are used as a growth material. 5. The method for growing a compound semiconductor crystal according to claim 1, wherein ZnTe and Zn are used as growth raw materials. 6. The method for growing a compound semiconductor crystal according to claim 1, wherein ZnTe, Zn, and Te are used as growth raw materials. 7. The method for growing a compound semiconductor crystal according to claim 1, wherein the substrate temperature is set at 22.
A crystal growth method for a compound semiconductor, wherein the temperature is in the range of 0 ° C to 350 ° C. 8. The compound semiconductor crystal growth method according to claim 1, wherein the molecular beam intensity ratio of Zn to Te is in the range of 1: 1.2 to 1: 5.0. A method for growing a crystal of a compound semiconductor, comprising: 9. The compound semiconductor crystal growth method according to claim 1, wherein the growth rate is in the range of 0.2 to 2.0 microns per hour. A semiconductor crystal growth method. 10. The method for growing a compound semiconductor crystal according to claim 1, wherein the temperature of Al is set to 700 to 900 ° C. 11. An optical semiconductor device comprising: (a) a substrate; and (b) an Al-doped n-type ZnTe layer formed on the substrate by a molecular beam epitaxy method. 12. An (a) substrate, (b) a buffer layer formed on the substrate, and (c) an Al-doped n-type ZnTe formed on the buffer layer by molecular beam epitaxy. An optical semiconductor device comprising: 13. An optical semiconductor device comprising: (a) a semiconductor layer; and (b) an Al-doped n-type ZnTe layer formed on the semiconductor layer by a molecular beam epitaxy method. . 14. An (a) substrate, (b) an Al-doped n-type ZnTe layer formed by molecular beam epitaxy formed on the substrate, and (c) a n-type ZnTe layer formed on the n-type ZnTe layer. An optical semiconductor device comprising a semiconductor layer or a metal layer. 15. An Al-doped n-type ZnTe layer formed on the semiconductor layer by molecular beam epitaxy, and (c) the n-type ZnT.
An optical semiconductor device comprising: a semiconductor layer or a metal layer formed on an e-layer. 16. The optical semiconductor device according to claim 11, wherein said substrate is a GaSb substrate, InAs.
Substrate, semiconductor substrate such as GaAs substrate, sapphire, Mg
An optical semiconductor device, which is an insulating substrate such as O or a ZnTe substrate. 17. The optical semiconductor device according to claim 12, wherein the buffer layer is a ZnTe epitaxy layer for a ZnTe substrate, a GaSb epitaxy layer for a GaSb substrate,
ZnTe epitaxy layer on ZnTe epitaxy layer or GaSb epitaxy layer, InAs epitaxy layer on InAs substrate, ZnTe epitaxy layer on ZnTe epitaxy layer or GaSb epitaxy layer, G on GaAs substrate
aAs epitaxy layer, ZnSe epitaxy layer, ZnTe
An epitaxy layer, a ZnSe epitaxy layer on a GaAs epitaxy layer, a ZnSe epitaxy layer on a GaAs epitaxy layer, or a ZnSe epitaxy layer and a ZnTe epitaxy layer on a GaAs epitaxy layer, a sapphire substrate, M
An optical semiconductor device comprising a ZnO layer in a gO substrate.