JPH10261839A - Semiconductor thin film and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit favorably a high AlGaAs multilayer film on an Al element and to contrive to apply the multilayer film to the manufacture of a device by a method wherein a p-type AlGaAs film, which is doped with carbon and is specified, is formed on a GaAs substrate with the B-face (311) as its main surface. SOLUTION: A laminated structure constituted by laminating P-type Alx Ga1-x As/P-type Aly Ga1-y As (x>=0.5 and y<0.5) layers is formed on the B-face (311) by a doping of carbon in an organometallic vapor epitaxial growth method. In the conditions of this growth, the amount of the partial pressure of the arsenic is set at an amount less than half of that of the face (100), the temperature of a P-type GaAs substrate 1 is made higher by 50 to 150 deg.C than that of the face (100) and moreover, a halogen-containing and carbon-doped material, such as a CCl4 and a CBr, is used. In this case, a semiconductor film is formed by an organometallic vapor growth method in a state that the ratio of the partial pressure of the arsenic to the partial pressure of a group III element is a ratio of 1 to 10 to 60 and the temperature of the substrate 1 is 700 to 800 deg.C. Thereby, the carbon fully contributes as an acceptor also on the B-face (311) and an activated growth layer can be obtained on the B-face (311).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to GaAs (31)
1) p-type Al _x Ga ₁ -x As (x ≧ 0.
5) and a method for manufacturing the same.

[0002]

2. Description of the Related Art A typical GaAs optical device is (10
0) Although grown on a substrate, if it is formed on the (311) plane, its anisotropy makes it possible to manufacture an optical device such as a surface emitting laser or a surface modulator having good polarization controllability. In fact,
A surface emitting laser using the (311) A plane for polarization control of a surface emitting laser has been manufactured by ATR and a group of Tokyo Tech [M. Takahashi et al., IEEE Photonics Te.
chnol. Lett., vol. 8 No. 6, p737, 1996].

A surface emitting laser on the (311) B plane has also been manufactured [Y. Kaneko et al., Electron Lett. Vol.3.
1, No.10.p805, 1995].

[0004] However, these are MBE (Molesula).
r Beam epitaxy: The crystal is grown by molecular beam epitaxy (MOVPE).
ourPhase Epitaxy)
It is considered that the characteristics are inferior to the laser grown on the (100) plane by the method.

[0005] It is expected that an element having high crystallinity and excellent characteristics can be obtained by growth by the MOVPE method.
The surface emitting laser on the (311) plane has never been grown by the MOVPE method. The surface emitting laser is manufactured using an AlGaAs layer having a high Al composition of 50% or more. However, the doping characteristics and crystallinity of AlGaAs on the (311) plane are considerably different from those on the (100) plane when the MOVPE method is used. This is because it is difficult to find appropriate growth conditions.

In addition, a p-type AlGaAs semiconductor multilayer film is formed by using a distributed Bragg reflector (DBR) of a surface emitting laser.
g reflector), a monolithic structure can be realized, which is advantageous in terms of planarization and wavelength control, but
The surface-emitting laser of Y. Kaneko et al. Uses a dielectric instead of a p-type semiconductor multilayer film to make a reflecting mirror.

The reason is that the p-type dopant is less likely to enter the B-plane, and therefore it is difficult to produce a low-resistance dopant. Therefore, it has been difficult to realize p-type AlGaAs having a high Al composition (50% or more) on the (311) B plane, and there has been no example applied to an optical device.

For controlling the plane of polarization of a surface emitting laser,
The (311) plane (there are two types, the A plane and the B plane) may be used. However, MO that can provide high quality crystals
The growth on the (311) plane by the VPE method has the following problems. That is, if Al _x Ga ₁ -x As (x ≧ 0.5) required for the surface emitting laser is grown on the (311) A plane, the conductivity of the grown layer will always be p-type. On the other hand, on the (311) B plane, the conductivity type is likely to be n-type,
There is a problem that a high-concentration p-type semiconductor layer cannot be obtained.

[0009]

As described above, the reason why the MBE is conventionally used and the MOVPE method is not used is that GaAs or Al _x Ga ₁ -x As (x <0.
The reason 5) is that the p-type dopant does not easily enter and the resistance does not easily become low.

[0010] In addition, the optimum crystal growth conditions for the (100) plane and the (311) A plane by MOVPE are, for example, a substrate temperature of 650 ° C, a ratio of arsine partial pressure to group III source pressure (V / III ratio) of 60. : AlAs on the (311) B surface under the condition of
It has been found that, when 1 .mu.m is grown, the hole concentration is about one order of magnitude lower than that of the (100) plane and the (311) A plane, and a grown layer whose surface state is extremely poor can be obtained.

Under the same growth conditions as the (100) plane, (3
11) Even if a surface emitting laser is manufactured on the B surface,
It has been discovered that the hole concentration of the p-type DBR made of s is smaller than 10 ¹⁸ cm ⁻³ , has high resistance, and has an extremely poor surface state and poor characteristics.

Further, in MBE, Be is (31
1) It has been reported as a dopant for Al _x Ga ₁ -x As (x <0.5) film on B-plane (Y. Kaneko et al., Electron
Lett.vol.31, No.10.p805, 1995).
There is a report of a hole concentration of 10 ¹⁷ cm ^{-3 when} Zn or C is doped into an As film (Zn: J. Crystal Growth vol.10).
7, p772, 1991; C: J. Crystal Growth vol. 118, p467, 199
2) However, in any case, there is no report of carbon-doped p-type Al _x Ga ₁ -x As (x ≧ 0.5).

According to the present invention, a multilayer film of high (50% or more) AlGaAs having a high Al element, which cannot obtain a good film on the (311) B surface by the conventional method, is satisfactorily deposited and applied to a device. It is an object to provide a semiconductor thin film and a manufacturing method thereof.

[0014]

According to the present invention, there is provided a semiconductor thin film having a GaAs having a (311) B plane as a main surface.
p-type Al doped on s substrate and doped with carbon
It is characterized by being composed of _X Ga _{1 -X} As (x ≧ 0.5).

On the other hand, the method for producing a semiconductor thin film of the present invention comprises:
The semiconductor thin film is formed by a metal organic chemical vapor deposition method in a state where a partial pressure ratio of arsenic to a group III element is 10 or more and 60 or less and a substrate temperature is 700 ° C. or more and 800 ° C. or less.

In the method for manufacturing a semiconductor thin film, the doping gas for carbon is a halogenated carbon.

In the method of manufacturing a semiconductor thin film, the carbon halide is one of CCl ₄ and CBr ₄ .

[0018] That is, in the present invention, (311) B p-type on the surface _{Al x Ga 1-x As /} Al y Ga 1-y As (x ≧
A stacked structure of 0.5, y <0.5) is produced by carbon doping in the metalorganic vapor phase epitaxial growth method. Under these growth conditions, the arsenic partial pressure is set to less than half the amount of the (100) plane, and the substrate temperature is 50 to 1 lower than that of the (100) plane.
The temperature is raised by 50 ° C., and a carbon doping material containing halogen such as CCl ₄ or CBr ₄ is used. From this (31
1) A growth layer in which carbon is sufficiently activated as an acceptor can be obtained also on the B side.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings, but the present invention is not limited thereto.

[First Embodiment] FIG. 1 is a cross-sectional view of an Al alloy according to the present invention.
5 is a diagram illustrating a relationship between a V / III ratio of surface homology and a growth temperature in growing an As layer of 1 μm. In the drawing, the symbol “○” indicates a good surface, and “△” indicates a surface with only a slight undulation (unevenness),
“X” indicates that the surface is poor, three-dimensionally growing, and there is mobility degradation.

It has been found that the lower the V / III ratio and the higher the substrate temperature, the better the surface of AlAs. FIG.
Means that the flow rate of CBr ₄ at the position corresponding to FIG.
The hole concentration of AlAs at 0 ^-6 mol / min is shown. According to FIG. 2, it was found that the hole concentration increased as the V / III ratio was reduced and the substrate temperature was increased. Also, it was confirmed that by increasing the flow rate of CBr ₄ , diffusion of the group III element was promoted by the effect of etching, and the surface condition was improved.

[Second Embodiment] FIG. 3 shows an embodiment of the present invention.
Is a surface emitting laser manufactured by the method described above. p type (311) B side
Using a GaAs substrate 1 for an oscillation wavelength of λ = 0.85 μm
And p-type Al with optical length λ / 4_0.25Ga_0.75Same as As layer
P-type Al with optical length λ / 4 _0.95Ga_0.05As layer as a pair
Reflective layer 2 composed of 37.5 pairs of repeating multilayer films
At a total pressure of 76 Torr, a substrate temperature of 700 ° C, and V / III = 15
And CBr_FourGrown using Then, three layers of GaAs
s quantum well layer and Al_0.3Ga_0.7Activity composed of As barrier layer
Spacer layer 3 having optical wavelength mλ including conductive layer, optical length λ / 4
N-type Al_0.25Ga_{0. 75}Like the As layer, the optical length λ / 4
n-type Al_0.95Ga_0.0526 pairs of pairs with As layer
Crystal growth structure composed of second reflective layer 4 composed of a turned multilayer film
Grew up.

Next, the SiO 2 is formed so as to have a diameter of 20 μmφ.
₂ was formed, and the element was separated by etching with reactive chlorine ions.

Next, the surface was flattened with polyimide 5, the SiO ₂ on the top of the device was peeled off, and an insulating film 6 of SiO ₂ was formed around the device again at 5000 °.

Finally, an n-electrode 7 made of AuGeNi was formed above the growth layer, and a p-electrode 8 made of AuZnNi was formed below the growth layer.

The characteristics of the surface emitting laser chip thus manufactured were examined. FIG. 4 shows a current-light output characteristic and a current-voltage characteristic of the surface emitting laser. It exhibited better characteristics than the conventional (100) surface emitting laser indicated by the broken line. Further, as shown in FIG.
1] It was confirmed that the control was performed so as to be orthogonal to the direction.

[0027]

As described above, according to the present invention, (3)
It was grown on 11) B plane _{Al X Ga 1- X As (x} ≧ 0.
5) / Al _y Ga _1-y As (y <0.5) stacked structure enables a p-type DBR to be formed on the (311) B plane, realizing a surface emitting laser with high characteristics. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a distribution diagram of the surface homology of AlAs.

FIG. 2 shows A when CBr ₄ flows at 2 × mol / min.
It is a distribution diagram of the hole concentration of 1As.

FIG. 3 is a sectional view of a surface emitting laser according to the present invention.

FIG. 4 is a diagram showing current vs. voltage characteristics and current vs. light output characteristics of a surface emitting laser according to the present invention.

FIG. 5 is a diagram showing a polarization direction of laser light of an 8 × 8 surface emitting laser array according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 p-type (311) B-plane GaAs substrate 2 first reflective layer 3 spacer layer 4 second reflective layer 5 polyimide 6 insulating film 7 n-electrode 8 p-electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Wakasada Onn 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Japan Telegraph and Telephone Corporation (72) Takashi Kurokawa 3-19, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. A (311) p-type Al _x G doped on carbon formed on a GaAs substrate having a B-plane as a main surface.
a _1-x As (x ≧ 0.5). 2. The semiconductor thin film according to claim 1, wherein the partial pressure ratio of arsenic to the group III element is 10 or more and 60 or less, and the semiconductor thin film is A method of manufacturing a semiconductor thin film, wherein the method is formed by a metal vapor deposition method. 3. The method for manufacturing a semiconductor thin film according to claim 2, wherein the doping gas for carbon is a halogenated carbon. 4. The method of manufacturing a semiconductor thin film according to claim 3, wherein the halogenated carbon is one of CCl ₄ and CBr ₄ .