JP3396323B2 - High resistance compound semiconductor layer, crystal growth method thereof, and semiconductor device using the high resistance compound semiconductor layer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high resistance compound semiconductor layer, a crystal growth method thereof, and a semiconductor device using the layer, and more particularly to a high resistance compound semiconductor layer formed by a metal organic chemical vapor deposition method. The present invention relates to the crystal growth method and a semiconductor device using the layer.

[0002]

2. Description of the Related Art Recently, InP whose substrate material is InP
A ternary compound, AlInAs, has been attracting attention as a material for a compound semiconductor layer used for optical devices and electronic devices of the system. Then, as a typical method for crystal-growing a compound semiconductor layer such as AlInAs, there are a molecular beam epitaxy (hereinafter referred to as MBE) method and a metal organic chemical vapor deposition (hereinafter referred to as MOCVD) method. Yes, for example, Journal of Crystal Growth 131 (1993) P.186-192
"Electrical properties and deep levels of InGaAs l
ayers grown by metalorganic chemical vapor deposit
ion "(S.Naritsuka, T.Tada, A.Wagai, S.Fujita and Y.Ash
izawa), when the crystal growth of the undoped AlInAs layer is performed by using the MBE method, the undoped AlInAs layer has a high resistance, and the MOCV
It is known that when the undoped AlInAs layer is crystal-grown by the D method, the undoped AlInAs layer exhibits n-type conduction.

FIG. 14 shows an undoped AlInAs film formed by the MOCVD method at a growth temperature of 620 to 700 ° C.
FIG. 3 is an energy band diagram of a layer, in which Ec, E
v, ESD, EA, and EDD represent the energy levels of the conduction band, valence band, shallow donor, shallow acceptor, and deep donor, respectively. Here, the donor level ESD, EDD, and the acceptor level EA as shown in FIG. 14 do not exist if the undoped AlInAs layer is an intrinsic semiconductor, but the intrinsic semiconductor is an ideal semiconductor. Is extremely difficult to form, and when this undoped AlInAs layer is formed by a usual forming method using the MOCVD method, the donors ESD, EDD, and the acceptor due to impurities introduced unintentionally are formed. The level EA is formed.

Then, the energy gap Ec- between the conduction band and the valence band in the undoped AlInAs layer.
Ev is 1.45 eV at room temperature, and each donor level ES
D, EDD, and acceptor level EA are as shown below. First, the shallow donor level ESD is formed by impurities such as Si and Se.
And the above conduction band level Ec is Ec-ESD≈5 me
It becomes V. The shallow acceptor level EA is formed by impurities such as Zn, and this level EA
And the valence band level Ev is Ev-EA ≈ 20
It becomes meV. Further, the deep donor level EDD is formed by oxygen, and the difference Ec-EDD between this level EDD and the conduction band level Ec is 0.3,0.4.
It has many values of 5,0.5 eV.

As described above, when the undoped AlInAs layer is formed by MOCVD at the growth temperature of 620 to 700 ° C., the Fermi level of the undoped AlInAs layer is located near the conduction band because there are few shallow acceptors. Electrons are excited at room temperature from a donor forming an energy level close to the conduction band level of the shallow donor and the deep donor, and the carrier concentration is 10 ¹⁶ cm ^−3.
(Hall measurement) shows n-type conduction.

By the way, the resistivity of the current blocking layer, the high resistance buffer layer, or the like in the above InP-based optical device and electronic device is 5 × 10 ⁴ Ω · cm.
A compound semiconductor having a resistivity of the order of 10 ³ to 10 ⁸ Ω · cm is generally called a high resistance compound semiconductor. However, MO
The above carrier concentration 10 ¹⁶ which was crystal-grown by the CVD method
The cm ^-3 undoped AlInAs layer has a resistivity of 1
Since it is Ω · cm or less, it cannot be used for the current blocking layer, the high resistance buffer layer, or the like, which is required to be a high resistance compound semiconductor.

Therefore, in order to increase the resistance of the compound semiconductor when it is formed by the MOCVD method, the compound semiconductor is
It is known to dope Fe having a deep acceptor level. For example, in JP-A-1-241817, the AlGaAs layer is made to contain Fe and the AlG layer is made to contain Fe.
It has been described to increase the resistance of the aAs layer, and Jpn.J.
Appl.Phys.Vol.31 (1992) pp, L376-L378 Part2, No.4A, 1 A
pril 1992 "Highly Resistive Iron-Doped AlInAs Laye
rs Grown by Metalorganic Chemical Vapor Depositio
n "(H.Ishikawa, M.Kamada, H.Kawai and K.Kaneko) has a concentration of 2 in the undoped AlInAs layer showing a residual carrier concentration of 1 to 2 × 10 ¹⁵ cm ^-3 and n-type conductivity. × 1
It has been shown that by doping Fe with 0 ¹⁷ atoms · cm ⁻³ , a high resistance AlInAs layer having a resistivity of the order of 10 ⁴ to 10 ⁶ Ω · cm can be obtained.
That is, the conventional high-resistivity AlInAs layer is either crystal-grown using the MBE method or Fe-grown by the MOCVD method.
It was obtained by any one of the methods of doping and crystal growing.

[0008]

The conventional high-resistance compound semiconductor layer is formed by the crystal growth method as described above, and by performing crystal growth of an undoped compound semiconductor using the MBE method, the compound Although it is possible to increase the resistance of a semiconductor, the reason why the resistance can be increased by using the MBE method is still unknown, and the MBE method is difficult to apply to a phosphorus-based compound semiconductor. On the other hand, when the MOCVD method is used, it is possible to perform growth utilizing the plane orientation dependency such as selective growth on an insulating film, and this is applied to both phosphorus-based and arsenic-based compound semiconductors. On the other hand, the application thereof is easy, but there is a problem that, when crystal growth of an undoped compound semiconductor is performed, the compound semiconductor exhibits n-type conduction. In order to compensate for this, it is possible to increase the resistance by doping the compound semiconductor with Fe as a dopant. However, the doped Fe is added to the p-type semiconductor formed adjacent to the compound semiconductor. It is generally known that it diffuses at a very high speed, and this diffused Fe deteriorates the electrical and optical characteristics of the compound semiconductor crystal, and reduces the reliability of electronic devices and optical devices using the same. Will be lost. Therefore, there is a problem that the crystal growth method for doping the compound semiconductor with Fe to increase the resistance, and the electronic device and the optical device provided with the high resistance compound semiconductor layer obtained by this growth method are not practical. It was

The present invention has been made in order to solve the above-mentioned problems, and the MOCVD method is used to grow a compound semiconductor layer used for InP-based electronic devices and optical devices with high reproducibility and high resistance. And a device of an electronic device and an optical device including the high resistance compound semiconductor layer by suppressing the diffusion of impurities contained in the high resistance compound semiconductor layer obtained by this growth into another compound semiconductor layer. An object of the present invention is to obtain a high-resistance compound semiconductor layer and a crystal growth method thereof, which can prevent deterioration of characteristics, and a semiconductor device using the layer.

[0010]

A high resistance compound semiconductor layer according to the present invention (claim 1) is an organic metal containing In, A
It is composed of a compound semiconductor mixed crystal obtained by vapor-phase growth of an organic metal containing 1 or a hydrogen compound containing As, or an organic metal, and the concentration of p-type impurities in the compound semiconductor mixed crystal is determined by the Fermi of the compound semiconductor mixed crystal. The level is a concentration that is located approximately in the center of the forbidden band.

The high-resistance compound semiconductor layer according to the present invention (claim 2) is composed of a compound semiconductor mixed crystal vapor-grown with the above three kinds of raw materials, and has a shallow acceptor level in the compound semiconductor mixed crystal. The concentration of the impurities that form the is set to a concentration required to position the Fermi level of the compound semiconductor mixed crystal at approximately the center of the forbidden band.

The high-resistance compound semiconductor layer according to the present invention (claim 3) is composed of a compound semiconductor mixed crystal vapor-grown with the above-mentioned three kinds of raw materials, and contains a group IV element of the compound semiconductor mixed crystal. The concentration of the acceptor impurities is set to a concentration at which the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band.

In the high resistance compound semiconductor layer according to the present invention (claim 4), carbon is used as the acceptor impurity of the group IV element.

The high-resistance compound semiconductor layer according to the present invention (claim 5) is composed of a compound semiconductor mixed crystal vapor-grown with the above-mentioned three kinds of raw materials, and contains a group II element of the compound semiconductor mixed crystal. The concentration of the acceptor impurities is set so that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band.

In the high resistance compound semiconductor layer according to the present invention (claim 6), beryllium or magnesium incorporated into the compound semiconductor mixed crystal by doping is used as the acceptor impurity of the group II element.

The high-resistance compound semiconductor layer according to the present invention (claim 7) has, in addition to the acceptor impurities of the group IV element or the group II element, 10 times the concentration of the acceptor impurities in the compound semiconductor mixed crystal. The impurities containing the deep donor level having the above concentration are contained. In the high-resistance compound semiconductor layer according to the present invention (claim 8), the impurity forming the deep donor level is oxygen taken into the compound semiconductor mixed crystal by doping.

Further, the high-resistance compound semiconductor layer according to the present invention (claim 9) is vapor-phase grown using an organic metal containing In, an organic metal containing Al, an organic metal containing Ga, and a hydrogen compound containing As as a raw material. Made of mixed compound semiconductor mixed crystal,
The concentration of impurities forming a deep donor and acceptor level in the compound semiconductor mixed crystal is set to a concentration at which the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band.

In the high-resistance compound semiconductor layer according to the present invention (claim 10), the impurities forming the deep donor and acceptor levels are oxygen incorporated into the compound semiconductor mixed crystal by doping. Is.

The crystal growth method for a high-resistance compound semiconductor layer according to the present invention (claim 11) uses an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal as a raw material. Crystals are grown at a predetermined low temperature by a metal chemical vapor deposition method, and an impurity having a concentration that causes the Fermi level of the compound semiconductor mixed crystal to be located at approximately the center of the forbidden band is added to the obtained compound semiconductor mixed crystal. It is designed to be imported.

The crystal growth method for a high-resistance compound semiconductor layer according to the present invention (claim 12) uses an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal as a raw material. Crystal growth is performed at a predetermined low temperature by the metal chemical vapor deposition method, and in the obtained compound semiconductor mixed crystal, the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of its forbidden band width. It is designed to take in impurities.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 13), the above-mentioned three kinds of raw materials are used to perform vapor phase growth at a predetermined low temperature by metal organic chemical vapor deposition method. Then, the compound semiconductor mixed crystal to be obtained is made to incorporate an impurity forming a shallow acceptor level in which the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the band gap. .

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (Claim 14), the above-mentioned three kinds of raw materials are used to perform vapor phase growth at a predetermined low temperature by metal organic chemical vapor deposition method. Then, the compound semiconductor mixed crystal thus obtained is made to incorporate a group IV element acceptor impurity having a concentration such that the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the band gap. Further, the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 15) is
The acceptor impurity of the group IV element is carbon.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 16), the compound semiconductor mixed crystal is crystal-grown by metal organic chemical vapor deposition using the above three kinds of raw materials. Further, at the time of this crystal growth, p-type impurities are doped at a concentration such that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 17), the compound semiconductor mixed crystal is grown by metal organic chemical vapor deposition using the above three kinds of raw materials. At the time of this crystal growth, the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band, and an impurity forming a shallow acceptor level is doped.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 18), the compound semiconductor mixed crystal is crystal-grown by metal organic chemical vapor deposition using the above three kinds of raw materials. Further, during the crystal growth, the Fermi level of the compound semiconductor mixed crystal is doped with an acceptor impurity of a group IV element at a concentration so as to be located in the approximate center of the forbidden band.

In the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 19), the above-mentioned doping is performed.
The acceptor impurity of the group IV element is carbon.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 20), the compound semiconductor mixed crystal is crystal-grown by the metal organic chemical vapor deposition method using the above three kinds of raw materials. In addition, during the crystal growth, the Fermi level of the compound semiconductor mixed crystal is doped with an acceptor impurity of a Group II element at a concentration so as to be located in the approximate center of the forbidden band.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 21), the above doping is performed.
Beryllium or magnesium is used as the acceptor impurity of the group II element.

In the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 22), impurities for forming a deep donor level are doped in addition to the acceptor impurities of the group II element. Is.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 23), oxygen is used as the impurity forming the deep donor level.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 24), the doping amount of oxygen is 10 times or more the doping amount of the acceptor impurity.

The crystal growth method for a high-resistance compound semiconductor layer according to the present invention (claim 25) is an organic metal containing In, an organic metal containing Al, a hydrogen compound or organic metal containing As, an organic metal containing Ga. Using metal as a raw material, crystal growth of compound semiconductor mixed crystal by metal organic chemical vapor deposition,
At the time of this crystal growth, the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band, and the impurities for forming the deep donor and acceptor levels are doped.

In the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 26), oxygen is used as the impurity forming the deep donor and acceptor levels.

In a semiconductor device according to the present invention (claim 27), the current blocking layer is the high resistance compound semiconductor layer according to any one of claims 1 to 10, and the p layer is p.
It has a -n-i-n structure.

A semiconductor device according to the present invention (claim 28) is a semiconductor device (claim 27) which is a long wavelength laser diode.

A semiconductor device according to the present invention (claim 29) is the semiconductor device (claim 27) used as a modulator.

A semiconductor device according to the present invention (claim 30) is a compound device in which the semiconductor device (claim 27) is integrated with a laser diode, a modulator, a waveguide and a photodiode.

Further, the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 31) is defined by claims 11 to 1.
5. In the crystal growth method for a high resistance compound semiconductor layer according to any one of 5 above, before crystal growth at the predetermined low temperature,
The substrate temperature is raised to a temperature higher than the growth temperature.

Further, the crystal growth method of the high resistance compound semiconductor layer according to the present invention (claim 32) is defined by claims 11 to 1.
In the crystal growth method of a high resistance compound semiconductor layer according to any one of 5), crystal growth is performed while adding an etching gas having an effect of removing a raw material species which becomes a nucleus of poly adhered to a mask. .

The crystal growth method for a high resistance compound semiconductor layer according to the present invention (claim 33) is the same as the crystal growth method for a high resistance compound semiconductor layer according to claim 32, wherein the etching gas is HCl gas or Cl2 gas was used.

[0041]

In the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, a compound obtained by crystal growth at a predetermined low temperature by the metal organic chemical vapor deposition method using the above three kinds of raw materials Since a p-type impurity having a concentration that positions the Fermi level of the compound semiconductor mixed crystal at approximately the center of the forbidden band is incorporated into the semiconductor mixed crystal,
The AlInAs mixed crystal exhibiting n-type conductivity in the undoped state can be made to have a high resistance by offsetting the donor concentration thereof, and by vapor phase epitaxy, the compound semiconductor layer adjacent to this can be formed. High resistance A with little impurity diffusion
An lInAs layer can be obtained.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the above three kinds of raw materials are used, and vapor phase growth is performed at a predetermined low temperature by metal organic chemical vapor deposition method, Impurities forming a shallow concentration of the acceptor level, which locates the Fermi level of the compound semiconductor mixed crystal in the approximate center of the forbidden band, are incorporated into the obtained compound semiconductor mixed crystal, so that the undoped state The AlInAs mixed crystal exhibiting n-type conductivity can be made to have a high resistance by offsetting the concentration of the shallow donor, so that the vapor phase epitaxy causes impurities in the compound semiconductor layer to be stacked adjacent thereto. It is possible to obtain a high resistance AlInAs layer with little diffusion.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the above three kinds of raw materials are used, and vapor phase growth is performed at a predetermined low temperature by metal organic chemical vapor deposition method, In the obtained compound semiconductor mixed crystal, the Fermi level of the compound semiconductor mixed crystal was made to take in the acceptor impurities of the group IV element at a concentration so that the compound semiconductor mixed crystal was positioned in the approximate center of the band gap. The AlInAs mixed crystal exhibiting type conductivity can be made to have a high resistance by offsetting the concentration of the shallow donor, and as a result, by vapor phase epitaxy, impurities to the compound semiconductor layer stacked adjacent thereto can be increased. High resistance AlInAs with little diffusion
Layers can be obtained.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metal organic chemical vapor deposition method using the above three kinds of raw materials, and During the crystal growth, p-type impurities are doped at a concentration such that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band. Therefore, AlIn showing n-type conductivity in the undoped state is formed.
A high resistance AlInAs layer can be obtained by offsetting the concentration of the shallow donor in the As mixed crystal to increase the resistance, and by vapor phase growth, the impurity diffusion into the compound semiconductor layer adjacent to this is small. Can be obtained.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metal organic chemical vapor deposition method using the above three kinds of raw materials, and Since the Fermi level of the compound semiconductor mixed crystal is located at the approximate center of the forbidden band at the time of this crystal growth, an impurity forming a shallow acceptor level is doped, so that the n-type of the undoped state is formed. The AlInAs mixed crystal exhibiting conductivity can be made to have a high resistance by offsetting the concentration of the shallow donor,
As a result, it is possible to obtain a high-resistance AlInAs layer in which the impurity diffusion into the compound semiconductor layer laminated adjacent thereto is small.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metal organic chemical vapor deposition method using the above three kinds of raw materials, and During this crystal growth, the Fermi level of the compound semiconductor mixed crystal is doped with an acceptor impurity of a group IV element at a concentration that positions the compound semiconductor compound crystal near the center of the forbidden band, so that n-type conduction occurs in the undoped state. The AlInAs mixed crystal shown can be made to have a high resistance by offsetting the concentration of the shallow donor, thereby obtaining a high resistance AlInAs layer with less impurity diffusion into the compound semiconductor layer laminated adjacent thereto. be able to.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metal organic chemical vapor deposition method using the above three kinds of raw materials, and During this crystal growth, the Fermi level of the compound semiconductor mixed crystal is doped with an acceptor impurity of a group II element at a concentration that positions it in the approximate center of the forbidden band, so that n-type conduction is achieved in the undoped state. The AlInAs mixed crystal shown can be made to have a high resistance by offsetting the concentration of the shallow donor, thereby obtaining a high resistance AlInAs layer with less impurity diffusion into the compound semiconductor layer laminated adjacent thereto. be able to.

Further, in the high-resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, in addition to the acceptor impurity of the group II element, the impurity forming the deep donor level is doped. AlInAs
By increasing the control range of the Fermi level of the mixed crystal, it is possible to increase the resistance thereof, thereby obtaining a high-resistance AlInAs layer with less impurity diffusion into the compound semiconductor layer laminated adjacent thereto. be able to.

Further, in the high resistance compound semiconductor layer and the crystal growth method thereof according to the present invention, an organic metal containing In, an organic metal containing Al, a hydrogen compound or organic metal containing As, or an organic metal containing Ga is used. As a raw material, a compound semiconductor mixed crystal was crystal-grown by a metal organic chemical vapor deposition method, and at the time of this crystal growth, impurities forming deep donor and acceptor levels were doped in the compound semiconductor mixed crystal. From the above, the number of deep donor and acceptor levels in the obtained compound semiconductor mixed crystal is increased, and the deep donor and acceptor levels are formed in the state where a large number of energy levels are formed near the center of the forbidden band. As a result, the Fermi level is located almost in the center of the forbidden band and the resistance is increased. It becomes a.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention, in the crystal growth method of the high resistance compound semiconductor layer according to any one of claims 11 to 15, the crystal is grown at the predetermined low temperature. Before the growth, the substrate temperature was raised to a temperature higher than the growth temperature, so that decomposition of phosphorus atoms (or hydrogen atoms), which has the effect of suppressing poly adhering to the mask, from phosphine is promoted. As a result, the high resistance compound semiconductor layer can be grown thick.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention, in the crystal growth method of the high resistance compound semiconductor layer according to any one of claims 11 to 15, a nucleus of poly adhered to the mask is used. Since the crystal growth is performed while adding the etching gas having the effect of removing the raw material species to be grown, the temperature range in which the high resistance compound semiconductor layer can be grown can be widened.

In the semiconductor device according to the present invention, the current blocking layer is the high resistance compound semiconductor layer according to any one of claims 1 to 10 as an i layer, pn-
Since the in-n structure is adopted, the resistance of the current blocking layer can be further increased.

[0053]

【Example】

Example 1. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A shows a high resistance Al obtained by a crystal growth method of a high resistance compound semiconductor layer according to the first embodiment of the present invention.
It is an energy band diagram of an InAs layer, and in the figure, E
c, Ev, ESD, EA, and EDD represent the energy levels of the conduction band, valence band, shallow donor, shallow acceptor, and deep donor, respectively, and NSD, NA, and NDD represent shallow donor, shallow acceptor, and deep donor, respectively. Indicates the level concentration.

FIG. 1 (b) is a sectional view of a semiconductor laser showing its layer structure in a simplified form.
nP layer 1, active layer 2, and p-InP layer 3 are formed,
The above three layers 1, 2 and 3 are etched in a mesa shape, and the etched portion has a high resistance A which becomes a current block layer.
After the lInAs layer 4 is embedded and formed, the p-In layer is formed.
On the P layer 3 and the high resistance AlInAs layer 4, p-I
The nP layer 3 is formed.

Next, the crystal growth method of the high resistance AlInAs layer 4 will be described. First, a vertical MOCVD furnace is used as an apparatus for crystal growth. And trimethylindium (TMI), trimethylaluminum (TMA), arsine (ASH3) (10%) are used as raw materials,
Flow rate of these material gases is 19cc / min and 2.5cc respectively
/ Min, 170cc / min in the reactor. The growth temperature is about 600 ° C to 700 ° C, which is a normal growth temperature.
Vapor phase growth is performed at a temperature lower than 500 ° C.

FIG. 4 shows the growth temperature of AlInAs at 650.
The results of examining the resistivity of the AlInAs obtained at each growth temperature by sequentially lowering the temperature from 50 ° C. by 50 ° C. are shown.
High-resistance AlInAs layer 4 having a resistivity of 5 × 10 ⁴ Ω · cm can be obtained by vapor-phase growing a crystal at a low temperature of 0 ° C.

Next, the mechanism by which a high resistivity is obtained by lowering the growth temperature will be described in detail. Figure 2
FIG. 3 is a diagram showing the results of analysis by SIMS (Secondary Ion Mass Spectroscopy) of changes in the impurity concentration in the compound semiconductor with respect to the growth temperature of the compound semiconductor, that is, the growth temperature dependence of the impurity concentration. It can be seen that when the crystal is grown at the growth temperature of 500 ° C., the concentration of oxygen, which is a deep donor, slightly increases, and the concentration of carbon (C), which is a p-type impurity and an acceptor species, also increases.

FIG. 3 shows the shallow acceptor concentration N.
It is a figure which shows the relationship between A, Fermi level, and Ec-EF, and this is about 600 degreeC-700 degreeC of normal growth temperature.
Then, as in the case of carbon, Zn having a level of a shallow acceptor level EA is doped to grow AlInAs and crystallize AlInAs to increase the Zn concentration.
This is a graph showing changes in the Fermi level of. From the solid line 1 in FIG. 3, in the range of the acceptor concentration NA from 2 × 10 ¹⁶ cm ⁻³ to 3 × 10 ¹⁷ cm ⁻³ , the Fermi level and Ec-EF are from 430 to 600.
It can be seen that the change is gentle up to meV. However,
Journal of Crystal Growth 131 (1993)
As described with reference to P.186 to 192, the deep donor level E formed by oxygen is originally formed in undoped AlInAs.
Although there are many DDs, in FIG. 3 above,
Fermi level due to increase in acceptor concentration NA,
In order to make the change of Ec-EF easy to understand, one of them is the donor level, Ec-EDD = 500me.
The graph shows the levels of V and the donor concentration N dd ≈3 × 10 ¹⁷ cm ^-3 , and the undoped AlInAs at this time.
The concentration of NSD-NA is about 1 × 10 ¹⁶ cm ^-3 . here,
Even if there are many donors with a level shallower than the above donor level, Ec-EDD = 500 meV, the step change in the above Fermi level, Ec-EF only increases by the number of the levels, and AlInAs is increased. The controllability of the acceptor concentration NA for making resistance is not impaired. When the deep donor concentration N DD is increased, the acceptor concentration NA and the Fermi level, Ec-EF
The relationship between and is as shown by the solid line 1 to the broken line m in FIG. 3, which expands the control range of the acceptor concentration NA.

That is, in order to increase the resistance of the compound semiconductor, it is necessary to set the Fermi level of the compound semiconductor to approximately the center of its forbidden band, and the forbidden band width is 1.45 eV.
When increasing the resistance of lInAs, the Fermi level is preferably set to about 0.45 to 1.0 eV. By setting the growth temperature to 500 ° C. as described above, the deep donor concentration N DD due to oxygen is slightly increased and the depth is shallow. The amount of carbon that forms the acceptor level is taken into the crystal to increase the carbon concentration, and this increase in the carbon concentration decreases the concentration obtained by subtracting the acceptor concentration NA from the shallow donor concentration NSD to decrease the Fermi of AlInAs. The level will be lowered. And the acceptor concentration NA by the above carbon is 2 ×
At about 10 ¹⁶ cm ⁻³ , the Fermi level of AlInAs becomes 430 meV, and as a result, the AlInAs has a high resistance AlInAs with a resistivity of 5 × 10 ⁴ Ω · cm.
Mixed crystals will be obtained.

As described above, in the first embodiment, T
Since MI, TMA, and AsH3 are used as raw materials and the MOCVD apparatus is used to grow the crystal in a vapor phase at a growth temperature of 500 ° C., carbon of p-type impurity that forms a shallow acceptor level is taken into the crystal. And the acceptor concentration NA increase, the Fermi level of the crystal decreases, which causes the Fermi level of the AlInAs mixed crystal formed by vapor phase growth to be at the center of the forbidden band. Located near 0.5 eV,
High resistance AlInAs can be used. For this reason,
Even when the high resistance AlInAs obtained by the vapor phase growth is used for the current blocking layer 4 of the semiconductor laser as shown in FIG. 1B, as in the conventional Fe-doped high resistance AlInAs, the adjacent p-InP is formed. High resistance AlI which does not cause impurity diffusion in the layer 3 to cause deterioration of device characteristics.
The nAs layer 4 can be obtained.

Although TMI, TMA, and AsH3 were used as raw materials for crystal growth in Example 1, an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal was used. It is sufficient if, for example, TE having an ethyl group is used in place of the above TMI and TMA.
Even if I and TEA are used, TBA is used instead of AsH3.
Needless to say, may be used.

Example 2. In the above Example 1, AlInA
Concentration of carbon that forms a shallow acceptor level that is naturally introduced into the crystal by setting the growth temperature when vapor-depositing the s mixed crystal to a temperature lower than the normal growth temperature of 600 ° C to 700 ° C. However, in Example 2, the acceptor raw material was introduced from the bubbler into the reaction tube to increase the resistance.

FIG. 5 is a graph for examining the Zn concentration dependence of the resistivity of AlInAs when Zn, which is an acceptor raw material, is examined. From FIG. 5, undoped AlInAs exhibiting n-type conduction is shown.
On the other hand, when the doping amount is gradually increased to increase the Zn concentration, the resistivity also gradually increases and the Zn concentration becomes 5 ×.
High resistance AlInAs around 10 ¹⁷ cm ^-3
Therefore, it can be seen that when the Zn concentration is further increased, AlInAs showing p-type conduction is obtained.

However, when Zn-doped AlInAs crystal-grown using Zn as the acceptor species is used for the current blocking layer 4'in a semiconductor laser as shown in FIG. 6, for example, the Zn-doped AlInAs high resistance is obtained. Zn diffuses from the layer 4 ′ to another layer adjacent thereto (or the opposite phenomenon occurs), and Zn contained in the layer 4 ′ decreases (or increases) and its resistivity decreases. As a result, the resistivity on both sides of the active layer 2 is lowered, and the current component that flows through the active layer and does not contribute to laser oscillation is increased to deteriorate the laser characteristics.

Therefore, in the second embodiment, beryllium, which is a p-type impurity that is less likely to diffuse than Zn and forms a shallow acceptor level as in the case of the first embodiment, is used as the dopant. did.

That is, as in the first embodiment, TMI, T is used as the raw material of AlInAs for crystal growth by the MOCVD method.
MA, AsH3 was used, and in addition thereto, Be (CH3C5H4) 2 (bismethylcyclopentadienylberyllium), which is an organic metal containing Be, was introduced into the reaction tube from a bubbler, and the Be was grown at a growth temperature of 600 ° C. The concentration is 2 × 10 ¹⁶ cm
By doping in the range of ⁻³ to 3 × 10 ¹⁷ cm ⁻³ , the Fermi level of the crystal formed by the vapor phase growth can be controlled in the vicinity of 0.5 eV.
High resistance AlInAs can be obtained. The above B
It is needless to say that even if the organic metal containing e is doped with beryllium using DEBe (diethyl beryllium), a high resistance AlInAs layer can be obtained by setting the Fermi level to around 0.5 eV.

Example 3. In the third embodiment of the present invention, magnesium is used as a dopant, and as shown in the second embodiment, Al is grown by MOCVD at a growth temperature of 600 ° C.
It is a vapor phase growth of InAs mixed crystal. At this time, the organic metal containing Mg includes Mg (CH3 C5 H4) 2
(Bismethylcyclopentadienylmagnesium) is used, and the doping Mg concentration is 2 × 10 ¹⁶ cm ⁻³ to 3
The range was × 10 ¹⁷ cm ^-3 .

Also in the third embodiment, the Fermi level of magnesium, which is a p-type impurity having a small diffusion coefficient and forming a shallow acceptor level, is set to be substantially at the center of the band gap in the crystal grown by vapor phase growth. Has high resistance A, which does not deteriorate device characteristics.
An lInAs layer can be obtained.

In Embodiments 3 and 2 above, the resistance of AlInAs can be increased because the p-type impurity forming the shallow acceptor level for doping cancels out the Fermi level of the shallow donor. Since it is due to the lowering, not the doping method, the above-mentioned magnesium or beryllium can be doped by using a generally known doping method, and the same effect can be obtained regardless of the doping method used. Further, carbon having a diffusion coefficient smaller than those of the two p-type impurities is introduced into the crystal by doping, rather than being spontaneously incorporated by lowering the growth temperature as in Example 1 above. It is good to do so.

Example 4. In the above-mentioned Examples 1 to 3, oxygen forming a deep donor level was naturally incorporated into the crystal by utilizing residual oxygen and H2O in the MOCVD apparatus. Is used to control the oxygen concentration in the crystal by doping. That is, 100 ppm oxygen gas based on He is MOC
TMA, TMI, AH3, Be in the reaction tube of the VD device
It is introduced together with (CH3 C5 H4) 2 to vapor-deposit oxygen and Be-doped AlInAs layers. At this time, since the deep donor concentration is about 1/10 with respect to the oxygen doping amount, oxygen doping is performed with an amount 10 times or more the beryllium doping amount.

In Example 4, since the oxygen concentration in the crystal was increased by doping, the control range of the Fermi level of the AlInAs mixed crystal formed by vapor phase growth can be expanded, and the high concentration can be obtained. Resistance AlI
There is an effect that the nAs layer can be obtained. Although the case where beryllium is used as the acceptor species has been described, this is not limited to beryllium, and the same effect can be obtained by using magnesium or carbon as in the third embodiment.

Example 5. Also, instead of oxygen gas, H
2 O gas or AlO (CH3) 3 [methoxyaluminum] may be bubbled with H2 to introduce oxygen, and the vapor pressure of the methoxyaluminum at 0.degree.
Since it is much smaller than the vapor pressure of TMA (9.2 mmHg) and 14 mmHg, it does not affect the composition of AlInAs. Also in the fifth embodiment, the same effect as in the fourth embodiment can be obtained.

Example 6. In Examples 1 to 5 described above, the Fermi level of the AlInAs mixed crystal grown by vapor phase epitaxy is positioned approximately at the center of the band gap by introducing the p-type impurity that forms the shallow acceptor level EA. In the sixth embodiment, Ga is
As shown in FIG. 7, the number of deep donor level ED D formed by oxygen is increased by adding Al.
The As mixed crystal has a high resistance.

That is, the oxygen level ET of the AlInAs mixed crystal having a composition that is lattice-matched to the InP substrate that is often used for InP-based optical devices or electronic devices has an oxygen level ET of 0.3,0.
45,0.05 eV, but G in the AlInAs mixed crystal
The composition (AlyGa1-y) xIn1-xAs that lattice-matches the InP substrate in the same manner as the above AlInAs mixed crystal by adding a.
When the AlGaInAs mixed crystal of (x = 0.48, 0 ≦ y ≦ 1) is used, the level of oxygen formation is deeper and increases, and Ec-ET ≈0.4 eV to EA
Many levels are formed up to -ET = 0.14 eV. Therefore, when the AlGaInAs mixed crystal is doped with oxygen, the AlGaInAs mixed crystal has a deep donor,
And because there is a deep acceptor, the Fermi level of the crystal is located in the center of the band gap,
This makes it possible to easily obtain a high resistance AlGaInAs layer.

The above AlGaInAs mixed crystal is In
Composition (AlyGa1-y) xIn1-x lattice-matched to P substrate
As (x = 0.48, 0 ≦ y ≦ 1),
A high resistance AlGaInAs layer can be obtained not only by the AlGaInAs layer having a composition that lattice-matches but also by the crystal growth method of the sixth embodiment.

Example 7. The seventh embodiment of the present invention is to manufacture a long wavelength semiconductor laser using a high resistance compound semiconductor layer. Before describing the present embodiment, first, a structure of a conventional long wavelength semiconductor laser and a manufacturing method thereof will be described. FIG. 8 is a diagram for explaining a structure of a conventional long wavelength semiconductor laser and a manufacturing method thereof. In the figure, 10
0 is an n-InP substrate, 1 is an n-InP layer formed on the n-InP substrate 100, 2 is an n-InP layer 1 and p-I.
An active layer sandwiched between the nP layer 3 and 200 is p-InP
The p-InGaAsP contact layer 10 formed on the layer 3a is Fe-doped I for realizing a current confinement structure.
It is an nP high resistance layer, and by setting the Fe concentration to 10 ¹⁶ cm ⁻³ , a resistivity of about 10 ⁸ Ωcm can be obtained, and it is the most used high resistance layer at present.

Next, a method of manufacturing this long wavelength semiconductor laser will be described. First, MO is formed on the n-InP substrate 100.
Using the CVD method, the n-InP layer 20 and the undoped layer 3
After sequentially growing the 0, p-InP layer 40, an SiO2 film is formed by sputtering, and an SiO2 stripe 50 is formed by using a normal photoresist technique (FIG. 8 (a)).

Next, a mesa as shown in FIG. 8 (b) is formed by wet etching using the SiO2 stripe 50 as a mask, and then the Fe--InP layer 10 is selectively embedded and grown on both sides of the mesa by MOCVD (FIG. 8 (c)). .

Then, after removing the SiO 2 stripes 50 with HF, the p-InP layer 3 is again formed by MOCVD.
An a, p-InGaAsP contact layer 200 is sequentially grown (FIG. 8 (d)).

As shown in FIG. 8D, the long-wavelength semiconductor laser thus formed has the Fe-InP layer 10, which is a high resistance layer, buried on both sides of the active layer 2 so that
The injected current is concentrated in the active layer 2 and the Fe-In
Since the refractive index of the P layer 10 is smaller than that of the active layer 2, the active layer 3
Although the light can be efficiently confined in the laser and the characteristics of the laser can be improved, there are the following problems.

FIG. 9 shows the result of SIMS analysis of the distributions of the respective dopants (Fe, Zn) in the crystal when the Fe-InP layer and the p-InP (dopant Zn) layer were adjacent to each other. In the figure, the horizontal axis is the depth from the surface, and the vertical axis is the concentrations of Fe and Zn. The solid and dotted lines show the profiles of Fe and Zn, respectively. From this figure, Fe
Diffuses into the Zn—InP layer by about 10 μm, and the Fe concentration at that time is close to the solid solution limit of Fe in InP 10 ¹⁷
It can be seen that it is about cm ^-3 .

That is, the long-wavelength semiconductor laser (see FIG.
In the laser structure shown in (d), diffusion of Fe from the Fe-InP layer 10 to the p-InP layer 3 and the active layer 3, and p
-Diffusion of Zn from the InP layer 4 to the active layer 3 deteriorates the electrical and optical characteristics of the laser.

The long wavelength semiconductor laser of this embodiment will be described below. First, the electrical characteristics of an undoped AlInAs layer grown by MOCVD at a growth temperature of 500 ° C. will be described. Undoped Al on n-InP substrate
A 0.48In0.52As layer is grown at a growth temperature of 500 ° C. for 3 μm, and then n and p-InP layers are grown at a growth temperature of 650.
Each was grown at 0.5 ° C. for 0.5 μm to form a p-n-i-n structure. This is processed into a mesa type and the current-voltage characteristic is n
It was compared with the -i-n structure and the p-i-n structure. In Figure 1,
The current-voltage characteristics of each structure are shown. In the n-i-n structure, only electrons are injected into the undoped AlInAs layer, so that the resistivity is as high as 2 × 10 ⁸ Ωcm, whereas in the p-i-n structure, n and p-InP are formed. Electrons and holes were injected into the undoped AlInAs layer from the layers and recombined, so that the resistivity became 1 Ωcm or less.
On the other hand, in the p-n-i-n structure, the injection of holes into the undoped AlInAs layer is suppressed by the n-InP layer between the p-InP layer and the undoped AlInAs layer, so that it is higher than 1 × 10 ¹⁰ Ωcm. The resistivity was obtained.

Therefore, in order to use the AlInAs layer as the current blocking layer of the long wavelength LD, the buried structure is p-type.
It is necessary to have an n-i-n structure. However, this is not the case when it is used as a high resistance layer when electrons or holes are used alone in an electronic device.

Next, as a current blocking layer, AlInAs is used.
FIG. 11 shows a long-wavelength LD manufacturing process in which a layer is used and the buried structure is a p-n-i-n structure. n-In
N-InP layer (1 μm, 1 × 10 ¹⁸ cm) on P substrate 100
^-3 ) 1, active layer (0.1 μm) 2, p-InP layer (0.
5 μm, 1 × 10 ¹⁸ cm ⁻³ ) 3 at a growth temperature of 600 ° C.
Sequential growth is performed using the OCVD method (FIG. 11 (a)). A SiO2 film is formed on the surface by sputtering, and a SiO2 stripe 50 is formed in the (110) direction by using a normal photoengraving technique. Next, a mesa is formed using an HBr-based etching solution (FIG. 11 (b)). Using the MOCVD method again, the undoped AlInAs layer (3 μm,
(High resistance) 6 and then n−I at a growth temperature of 600 ° C.
nP current blocking layer (0.5 μm, 1 × 10 ¹⁸ cm ⁻³ ) 7
Is selectively grown on the SiO2 stripe 5 without growing a polycrystal (FIG. 11 (c)). After the SiO2 stripe 5 were removed by HF series etching solution, p-InP layer ^{(1μm, 1 × 10 18 cm} -3) 3a, p-InGaAs contact layer ^{(1μm, 1 × 10 19 cm} -3) 200 again M
A long-wavelength LD structure is produced by growing by the OCVD method (FIG. 1).
1 (d)).

The point of this manufacturing method is the process shown in FIG. 11 (c). Figure 1 shows the growth temperature profile at this time.
2 shows. Normally, the growth temperature of the high resistance undoped AlInAs layer 4 is 500, as described in the first embodiment.
Growth is started after the temperature is raised to ° C by the phosphorus pressure (profile a). However, in this case, the undoped AlInAs layer 4 can be selectively grown only about 1 μm (about 1 hour in time). If an attempt is made to grow a film thickness greater than that, poly-AlInAs crystals are deposited on the SiO2 stripes 50. In order to operate the laser at high speed, it is necessary to reduce the parasitic capacitance of the laser, and for that purpose, it is necessary to make the undoped AlInAs layer 4 as thick as possible. For example, if the transmission rate of the laser output is 2.5 to 10 Gb / s, the film thickness of the undoped AlInAs layer 4 needs to be about 3 μm.

Then, once the substrate temperature (for example, 600 ° C.) higher than the growth temperature of the undoped AlInAs layer is raised, the temperature is lowered to 500 ° C. to grow the undoped AlInAs layer 4 up to about 3 μm SiO 2 Buried growth can be performed without depositing a poly-AlInAs crystal on the stripe 5 (profile b).

This is because the phosphorus atom (or hydrogen atom) decomposed from phosphine before the growth covers the entire surface of the SiO2 stripe 5, so that the polyAlInAs crystal is changed to SiO2.
This is to prevent adhesion to the film. Further, since the decomposition of phosphine can be promoted by increasing the temperature at which the phosphine is flowing before the growth of the undoped AlInAs layer 4, the profile of (b) is more undoped than that of (a) of FIG. The InInAs layer 4 can be selectively grown thick.

As described above, Al at a low temperature of 500 ° C.
The InAs layer is formed on the SiO2 stripe 5 by poly-AlIn.
In order to perform selective burying growth without attaching As crystals, it is extremely important to control the temperature profile before growth.

Long-wavelength LD manufactured by the manufacturing method of this embodiment
FIG. 13 shows the optical output / injection current characteristics of the. The long wavelength LD
Oscillates at a threshold current of 8 mA, and it can be seen that good characteristics are obtained.

In the seventh embodiment as described above, the undoped AlInAs layer 4 is selected in the manufacturing process of the long wavelength LD in which the unblocked AlInAs layer is used as the current blocking layer and the buried structure is the p-n-i-n structure. The embedded growth is performed by raising the substrate temperature to a temperature higher than the growth temperature (500 ° C.) and then decreasing the temperature to 500 ° C. Therefore, the temperature at which the phosphine flows before the growth of the undoped AlInAs layer 4 becomes high, The decomposition of phosphine into phosphorus atoms (or hydrogen atoms) is promoted, the phosphorus atoms (or hydrogen atoms) cover the entire surface of the SiO2 stripe 5, and it is possible to suppress the adhesion of polyAlInAs crystals to the SiO2 film. . Therefore, undoped AlInA
The s-layer 4 film can be selectively grown thick, and a long-wavelength LD capable of operating the laser at high speed can be obtained.

Further, the undoped AlInAs layer 4 has F
It does not contain very diffusible dopants such as Fe in the e-InP layer. Therefore, by using Be, which is more difficult to diffuse than Zn, as the p-type dopant of the p-type InP layer, the amount of impurities diffused into the active layer 3 can be suppressed, so that the long-wavelength LD has an impurity profile as designed. Can be manufactured. In this embodiment, a SiO2 film is used as a mask, but this is SiO1-x.
The same effect can be obtained by using an Nx (0 <x≤1) film.

Example 8. In Example 7 above, undoped A
It has been described that the buried layer thickness of the undoped AlInAs layer 4 is increased by changing the temperature profile before the growth of the lInAs layer 4. In this case, the temperature at which the selective burying growth can be performed is 500 ±, as described in the first embodiment.
Very narrow at 25 ° C. In this embodiment, the growth temperature range is expanded by adding a trace amount of etching gas during growth.

The long wavelength semiconductor laser of this embodiment will be described below. Undoped AlInAs layer 4 of FIG. 11 (c)
HCl gas (or Cl2 gas) 5-20 CC /
Grow while adding about min. At this time, the heating profile may be either (a) or (b) in FIG.
HCl is poly AlI attached to the SiO2 stripe 50.
Since it has the effect of removing the raw material species that become the nuclei of the nAs crystal, the temperature range in which selective burying growth is possible is 475 to 600
Can be expanded up to ° C.

When removing the SiO 2 stripes 50 from the structure of FIG. 11C, the undoped AlInAs layer 4 is removed.
The exposed portion of the surface, that is, the portion where the SiO2 stripe 50 is in contact with the undoped AlInAs layer 6 is easily oxidized. If the oxidized region is wide, the p-InP layer 3a will not grow flat. Then p
Before the -InP layer 3a is grown, HCl gas is caused to flow, and the oxidized surface layer is lightly etched so that the p-InP layer 8 can be grown flat.

In the eighth embodiment, the undoped AlInAs layer 4 is selected in the manufacturing process of the long wavelength LD in which the unblocked AlInAs layer is used as the current blocking layer and the buried structure is the p-n-i-n structure. Buried growth is performed by adding HCl gas (or Cl2 gas) 5 to 5
Since it was done while adding about 20 CC / min, HC
Poly AlInA attached to the SiO2 stripe 50
By removing the raw material seed that becomes the nucleus of the s crystal, the temperature range in which the selective burying growth can be performed can be expanded to 475 to 600 ° C. Therefore, even if the growth temperature is not severely controlled, it is possible to obtain a long-wavelength LD capable of operating at high speed, in which the film of the undoped InInAs layer 4 is selectively grown thick.

Further, the undoped AlInAs layer 4 has F
It does not contain very diffusible dopants such as Fe in the e-InP layer. Therefore, by using Be, which is more difficult to diffuse than Zn, as the p-type dopant of the p-type InP layer, the amount of impurities diffused into the active layer 3 can be suppressed, so that the long-wavelength LD has an impurity profile as designed. Can be manufactured.

In the seventh and eighth embodiments, the long wavelength LD
Although the single unit is described, it may be applied to a single modulator configured by reversing the operating voltage, or an embedded layer of a composite device in which an LD, a modulator, a waveguide, and a PD are integrated, The same effect as above can be obtained.

[0099]

According to the present invention, an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, and an organic metal are used as raw materials, and a vapor phase is formed at a predetermined low temperature by a metal organic chemical vapor deposition method. By growing the compound semiconductor mixed crystal, an impurity having a concentration that locates the Fermi level of the compound semiconductor mixed crystal in the approximate center of the forbidden band was introduced. AlI showing conduction
The resistance of the nAs mixed crystal can be increased by canceling out the donor concentration thereof, and as a result, high resistance in which impurity diffusion into the compound semiconductor layer adjacent to the nAs mixed crystal is suppressed by using the vapor phase growth method. There is an effect that the compound semiconductor layer can be formed with good reproducibility.

According to the present invention, an organic metal containing In,
A compound semiconductor mixed crystal is obtained by subjecting an organic metal containing Al, a hydrogen compound containing As, and an organic metal as a raw material to vapor phase growth at a predetermined low temperature by a metal organic chemical vapor deposition method to obtain a compound semiconductor mixed crystal. Since a p-type impurity having a concentration that positions the Fermi level of Al in the vicinity of the forbidden band is introduced, Al that exhibits n-type conduction in the undoped state is introduced.
The resistance of the InAs mixed crystal can be increased by canceling out the donor concentration, and as a result, high resistance in which impurity diffusion into the compound semiconductor layer adjacent to the InAs mixed crystal is suppressed by using the vapor phase growth method. There is an effect that the compound semiconductor layer can be formed with good reproducibility.

Further, according to the present invention, the above-mentioned three kinds of raw materials are used to carry out vapor phase growth at a predetermined low temperature by a metal organic chemical vapor deposition method, and the compound semiconductor is mixed in the compound semiconductor mixed crystal obtained. Impurities that form a shallow acceptor level with a concentration that positions the Fermi level of the mixed crystal at approximately the center of the forbidden band were introduced, so that an AlInAs mixed crystal exhibiting n-type conduction in the undoped state was selected. The resistance of the shallow donor can be offset to increase the resistance, and as a result, the high resistance compound semiconductor in which the impurity diffusion into the compound semiconductor layer adjacent to the compound semiconductor layer is suppressed by using the vapor phase growth method. The layer can be obtained with good reproducibility.

According to the present invention, the compound semiconductor is mixed in the compound semiconductor mixed crystal obtained by vapor-depositing the above-mentioned three kinds of raw materials by a metalorganic chemical vapor deposition method at a predetermined low temperature. Since a group IV element acceptor impurity having a concentration that positions the Fermi level of the mixed crystal at approximately the center of the forbidden band is introduced, an AlInAs mixed crystal exhibiting n-type conduction in an undoped state is The resistance of the shallow donor can be increased by offsetting the concentration of the shallow donor, and as a result, a high resistance compound semiconductor layer in which impurity diffusion into the compound semiconductor layer adjacent to the compound semiconductor layer is suppressed by the vapor phase growth method. There is an effect that can be obtained with good reproducibility.

According to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metalorganic chemical vapor deposition method using the above-mentioned three kinds of raw materials, and during the crystal growth, the compound semiconductor mixed crystal is grown. Since the Fermi level of the compound semiconductor mixed crystal is doped with a p-type impurity at a concentration that is located approximately in the center of the forbidden band, an AlInAs mixed crystal exhibiting n-type conduction in an undoped state is The resistance of the shallow donor can be increased by offsetting the concentration of the shallow donor, and as a result, a high resistance compound semiconductor layer in which impurity diffusion into the compound semiconductor layer adjacent to the compound semiconductor layer is suppressed by the vapor phase growth method. There is an effect that can be obtained with good reproducibility.

Further, according to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metalorganic chemical vapor deposition method using the above three kinds of raw materials, and at the time of this crystal growth, the compound semiconductor mixed crystal is formed in the compound semiconductor mixed crystal. Since the Fermi level of the compound semiconductor mixed crystal is located near the center of the forbidden band, the impurity forming the shallow acceptor level is doped, so that AlIn that exhibits n-type conductivity in the undoped state is obtained.
The resistance of the As mixed crystal can be increased by offsetting the concentration of the shallow donor, and as a result, diffusion of impurities into the compound semiconductor layer adjacent to the As mixed crystal can be suppressed by using the vapor phase growth method. The high resistance compound semiconductor layer can be obtained with good reproducibility.

According to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metalorganic chemical vapor deposition method using the above three kinds of raw materials, and the compound semiconductor mixed crystal is grown in the compound semiconductor mixed crystal during the crystal growth. Since the Fermi level of the compound semiconductor mixed crystal is doped with an acceptor impurity of a group IV element at a concentration that locates the Fermi level at approximately the center of the forbidden band, an AlInAs mixed crystal exhibiting n-type conduction in an undoped state is formed. ， By reducing the concentration of the shallow donor, it is possible to increase the resistance. As a result, using the vapor phase epitaxy method,
There is an effect that a high-resistance compound semiconductor layer in which the diffusion of impurities into the adjacent compound semiconductor layer is suppressed can be obtained with good reproducibility.

According to the present invention, the compound semiconductor mixed crystal is crystal-grown by the metalorganic chemical vapor deposition method using the above-mentioned three kinds of raw materials, and during the crystal growth, the compound semiconductor mixed crystal is formed in the compound semiconductor mixed crystal. Since the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band, the group II element acceptor impurity is doped,
The AlInAs mixed crystal exhibiting n-type conduction in the undoped state can be made to have a high resistance by offsetting the concentration of the shallow donor, and as a result, by using the vapor phase growth method,
There is an effect that a high-resistance compound semiconductor layer in which the diffusion of impurities into the adjacent compound semiconductor layer is suppressed can be obtained with good reproducibility.

Further, according to the present invention, in addition to the acceptor impurities of the group II element, impurities forming a deep donor level are doped, so that the AlInA
By expanding the control range of the Fermi level of the s mixed crystal, the resistance becomes higher, and as a result, the diffusion of impurities into the compound semiconductor layer adjacent thereto can be suppressed by using the vapor phase growth method. There is an effect that a high resistance compound semiconductor layer can be obtained with higher reproducibility.

Further, according to the present invention, an organic metal containing In, an organic metal containing Al, a hydrogen compound or organic metal containing As, or an organic metal containing Ga is used as a raw material, and a compound is prepared by a metal organic chemical vapor deposition method. Since the semiconductor mixed crystal is crystal-grown and the compound semiconductor mixed crystal is doped with impurities that form a deep donor and acceptor level during the crystal growth, the obtained compound semiconductor mixed crystal has a deep donor and acceptor level. With the number of acceptor levels increasing and a large number of energy levels formed near the center of the forbidden band, the Fermi level of the deep donor and acceptor levels is doped by doping with impurities. Is located almost in the center of the forbidden band, and as a result, a high resistance compound in which diffusion of impurities into the compound semiconductor layer adjacent to this is suppressed. There is an effect that it is possible to obtain a conductive layer with good reproducibility.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention, in the method of crystal growth of the high resistance compound semiconductor layer according to any one of claims 11 to 15, at the predetermined low temperature. Since the substrate temperature is raised to a temperature higher than the growth temperature before crystal growth, the decomposition of phosphorus atoms (or hydrogen atoms) from the phosphine, which has the effect of suppressing poly adhering to the mask, is prevented. This is promoted, which has the effect of allowing the high-resistance compound semiconductor layer to grow thick.

Further, in the crystal growth method of the high resistance compound semiconductor layer according to the present invention, in the method of crystal growth of the high resistance compound semiconductor layer according to any one of claims 11 to 15, a method of depositing poly on the mask is used. Since the crystal growth is performed while adding the etching gas having the effect of removing the raw material species serving as the nuclei, there is an effect that the temperature range in which the high resistance compound semiconductor layer can be grown can be widened.

In the semiconductor device according to the present invention, the current blocking layer has the high resistance compound semiconductor layer according to any one of claims 1 to 10 as an i layer, pn-
Since it has the in-n structure, there is an effect that the resistance of the current blocking layer can be further increased.

[Brief description of drawings]

FIG. 1 is a high resistance AlI according to a first embodiment of the present invention.
Energy band diagram of nAs layer and the high resistance AlInA
Sectional drawing of the semiconductor laser provided with an s layer.

FIG. 2 is a diagram showing the growth temperature dependence of the impurity concentration in the first embodiment.

FIG. 3 is a diagram showing a relationship between an acceptor concentration and a Fermi level in Example 1 described above.

FIG. 4 is a diagram showing the growth temperature dependence of the resistivity of the AlInAs mixed crystal in Example 1 at room temperature.

FIG. 5 is a view for explaining Embodiments 2 and 3 of the present invention,
The figure which shows the Zn concentration dependence of the resistivity of a Zn dope AlInAs mixed crystal.

FIG. 6 is a cross-sectional view of a semiconductor laser including a Zn-doped AlInAs layer for explaining the above-mentioned Examples 2 and 3.

FIG. 7 is a high resistance AlG according to a sixth embodiment of the present invention.
Energy band diagram of aInAs layer.

FIG. 8 is a diagram for explaining a conventional method for manufacturing a long wavelength semiconductor LD using a high resistance buried layer.

FIG. 9: Fe-InP layer and p-InP (dopant Z
The figure which shows the result of SIMS analysis of the distribution of each dopant (Fe, Zn) in a crystal | crystallization when it was adjacent to the (n) layer.

FIG. 10 is a diagram showing current-voltage characteristics due to the difference in the upper and lower structures of the AlInAs layer for explaining the seventh embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the method of manufacturing the long wavelength semiconductor laser device according to the seventh embodiment.

FIG. 12 is a diagram showing a temperature profile before growing an AlInAs burying layer in Example 7;

FIG. 13 is a diagram showing optical output-injection current characteristics of the long wavelength semiconductor laser according to the seventh embodiment.

FIG. 14 is an energy band diagram of a conventional AlInAs layer.

[Explanation of symbols]

1 n-InP, 2 active layer, 3,3 ap-InP,
4 High resistance AlInAs layer (current blocking layer), 4 '
Zn-doped AlInAs high resistance layer (current blocking layer),
10 Fe-doped InP high resistance layer (current blocking layer),
20 n-InP layer, 30 undoped layer, 40 p-
InP layer, 50 SiO2 stripe, 100 n-I
nP substrate, 200 p-InGaAsP contact layer,
Ec conduction band level, Ev valence band level, ESD shallow donor level, EA shallow acceptor level, EDD
Deep donor level, NSD shallow donor concentration, NDD deep donor concentration, NA acceptor concentration.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takuji Sonoda 4-1-1, Mizuhara, Itami City, Hyogo Prefecture Mitsubishi Electric Corp. Optical & Microwave Device Development Laboratory (56) Reference JP-A-4-72720 (JP) , A) JP 3-22519 (JP, A) JP 3-218008 (JP, A) JP 3-148112 (JP, A) JP 61-48917 (JP, A) JP 1-138784 (JP, A) JP-A-1-241817 (JP, A) JP-A-59-124170 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/205 C30B 25/00 C30B 29/40 502 H01S 5/30

Claims (33)

(57) [Claims] 1. A high-resistance compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are stacked, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal is used as a raw material. It is composed of a phase-grown compound semiconductor mixed crystal, and the compound semiconductor mixed crystal contains a p-type impurity having a concentration that positions the Fermi level of the compound semiconductor mixed crystal in the approximate center of the forbidden band. A high resistance compound semiconductor layer characterized by the above. 2. A high-resistance compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are stacked, and an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal is used as a raw material. Impurities that form a phase-grown compound semiconductor mixed crystal and that form a shallow acceptor level in the compound semiconductor mixed crystal in a concentration that positions the Fermi level of the compound semiconductor mixed crystal in the approximate center of the forbidden band A high-resistance compound semiconductor layer, which comprises: 3. In a high-resistance compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are stacked, an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal is used as a raw material. It is composed of a phase-grown compound semiconductor mixed crystal, and the compound semiconductor mixed crystal contains a group IV element acceptor impurity in a concentration such that the Fermi level of the compound semiconductor mixed crystal is located approximately in the center of the forbidden band. A high resistance compound semiconductor layer characterized in that 4. The high resistance compound semiconductor layer according to claim 3, wherein the acceptor impurity of the group IV element is carbon. 5. A high-resistivity compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are stacked, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic metal is used as a raw material. It is composed of a phase-grown compound semiconductor mixed crystal, and the compound semiconductor mixed crystal contains a group II element acceptor impurity in a concentration such that the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band. A high resistance compound semiconductor layer characterized in that 6. The high-resistance compound semiconductor layer according to claim 5, wherein the acceptor impurity of the group II element is beryllium or magnesium incorporated in the compound semiconductor mixed crystal by doping. Resistive compound semiconductor layer. 7. The high-resistance compound semiconductor layer according to claim 3, wherein, in addition to the acceptor impurities of the group IV element or the group II element, the concentration is 10 times or more as deep as the concentration of the acceptor impurities. A high-resistance compound semiconductor layer, which contains an impurity forming a donor level. 8. The high resistance compound semiconductor layer according to claim 7, wherein the impurity forming the deep donor level is oxygen taken into the compound semiconductor mixed crystal by doping. Resistive compound semiconductor layer. 9. A high-resistivity compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are laminated, wherein an organic metal containing In, an organic metal containing Al, an organic metal containing Ga, a hydrogen compound containing As, or It is composed of a compound semiconductor mixed crystal vapor-grown from an organic metal as a raw material, and the compound semiconductor mixed crystal contains a deep donor having a concentration such that the Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band. And a high-resistance compound semiconductor layer containing impurities forming an acceptor level. 10. The high-resistance compound semiconductor layer according to claim 9, wherein the impurity forming the deep donor and acceptor levels is oxygen incorporated into the compound semiconductor mixed crystal by doping. High resistance compound semiconductor layer. 11. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. Using a metal as a raw material, crystal growth is performed at a predetermined low temperature by a metal organic chemical vapor deposition method, and in a compound semiconductor mixed crystal obtained, the Fermi level of the compound semiconductor mixed crystal is set at approximately the center of the band gap. Of the concentration to be placed,
A crystal growth method for a high-resistance compound semiconductor layer, which is characterized by incorporating impurities. 12. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising a stack of compound semiconductor layers having different compositions, comprising: an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. Using a metal as a raw material, crystal growth is performed at a predetermined low temperature by a metal organic chemical vapor deposition method, and in a compound semiconductor mixed crystal obtained, the Fermi level of the compound semiconductor mixed crystal is set at approximately the center of the band gap. Of the concentration to be placed,
A crystal growth method for a high-resistance compound semiconductor layer, characterized by incorporating p-type impurities. 13. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, comprising: an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. Using a metal as a raw material, crystal growth is performed at a predetermined low temperature by a metal organic chemical vapor deposition method, and in a compound semiconductor mixed crystal obtained, the Fermi level of the compound semiconductor mixed crystal is set at approximately the center of the band gap. Of the concentration to be placed,
A crystal growth method for a high-resistance compound semiconductor layer, characterized by incorporating impurities forming a shallow acceptor level. 14. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic compound containing As. The Fermi level of the compound semiconductor mixed crystal obtained by vapor-depositing a metal as a raw material at a predetermined low temperature by a metalorganic chemical vapor deposition method at a predetermined low temperature, and the Fermi level of the compound semiconductor mixed crystal is almost at the center of the band gap. Of the concentration to be placed in
A crystal growth method for a high-resistance compound semiconductor layer, which is characterized in that acceptor impurities of group IV elements are incorporated. 15. The crystal growth method of a high resistance compound semiconductor layer according to claim 14, wherein the acceptor impurity of the group IV element is carbon. 16. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device in which compound semiconductor layers having different compositions are stacked, comprising: an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. Using a metal as a raw material, a compound semiconductor mixed crystal is crystal-grown by a metal organic chemical vapor deposition method, and at a concentration such that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band during the crystal growth, A crystal growth method for a high-resistance compound semiconductor layer, which comprises doping with a p-type impurity. 17. A method of crystal-growing a high resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic compound containing As. Using a metal as a raw material, a compound semiconductor mixed crystal is crystal-grown by a metal organic chemical vapor deposition method, and at the time of this crystal growth, a Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band. , A method for crystal growth of a high-resistance compound semiconductor layer, which is characterized by doping an impurity that forms a shallow acceptor level. 18. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. Using a metal as a raw material, a compound semiconductor mixed crystal is crystal-grown by a metal organic chemical vapor deposition method, and at a concentration such that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band during the crystal growth, A crystal growth method for a high-resistance compound semiconductor layer, characterized by doping an acceptor impurity of a group IV element. 19. The crystal growth method of a high resistance compound semiconductor layer according to claim 18, wherein the acceptor impurity of the group IV element to be doped is carbon. . 20. A method of crystal-growing a high resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, wherein an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As or an organic compound containing As. Using a metal as a raw material, a compound semiconductor mixed crystal is crystal-grown by a metal organic chemical vapor deposition method, and at a concentration such that the Fermi level of the compound semiconductor mixed crystal is located in the approximate center of the forbidden band during the crystal growth, A crystal growth method for a high-resistance compound semiconductor layer, characterized by doping an acceptor impurity of a group II element. 21. The crystal of a high resistance compound semiconductor layer according to claim 20, wherein the acceptor impurity of the group II element to be doped is beryllium or magnesium. Growth method. 22. The crystal growth method for a high resistance compound semiconductor layer according to claim 18, further comprising an impurity forming a deep donor level in addition to the acceptor impurities of the group II element or the group IV element. A crystal growth method for a high-resistance compound semiconductor layer characterized by doping. 23. The crystal growth method of a high resistance compound semiconductor layer according to claim 22, wherein the impurity forming the deep donor level is oxygen. . 24. The high resistance compound semiconductor layer according to claim 23, wherein the doping amount of oxygen is 10 times or more the doping amount of the acceptor impurity. Layer crystal growth method. 25. A method of crystal-growing a high-resistance compound semiconductor layer in a semiconductor device comprising compound semiconductor layers having different compositions, comprising: an organic metal containing In, an organic metal containing Al, a hydrogen compound containing As, or an organic material containing As. A metal or an organic metal containing Ga is used as a raw material, and a crystal is grown by a metal organic chemical vapor deposition method, and at the time of this crystal growth, a Fermi level of the compound semiconductor mixed crystal is located at approximately the center of the forbidden band. , A method for crystal growth of a high-resistance compound semiconductor layer, which comprises doping impurities forming deep donor and acceptor levels. 26. The crystal of a high resistance compound semiconductor layer according to claim 25, wherein the impurity forming the deep donor and acceptor levels is oxygen. Growth method. 27. A semiconductor device in which compound semiconductor layers having different compositions are laminated, wherein the current blocking layer is the high resistance compound semiconductor layer according to any one of claims 1 to 10 as an i-layer, pn -I-
A semiconductor device having an n structure. 28. The semiconductor device according to claim 27, wherein the semiconductor device is a long-wavelength laser diode. 29. The semiconductor device according to claim 27, wherein the semiconductor device is a modulator. 30. The semiconductor device according to claim 27, wherein the semiconductor device is a composite device in which a laser diode, a modulator, a waveguide, and a photodiode are integrated. 31. The crystal growth method for a high resistance compound semiconductor layer according to claim 11, wherein the substrate temperature is set to a temperature higher than the growth temperature before crystal growth is performed at the predetermined low temperature. A method for growing a crystal of a high resistance compound semiconductor layer, which comprises raising the temperature. 32. The crystal growth method for a high resistance compound semiconductor layer according to claim 11, while adding an etching gas having an effect of removing a raw material species which becomes a nucleus of poly adhered to the mask. A crystal growth method for a high-resistance compound semiconductor layer, which comprises crystal growth. 33. The crystal growth method of a high resistance compound semiconductor layer according to claim 32, wherein the etching gas is HCl gas or Cl 2 gas.