JPH02101784A - Manufacture of quantum well fine wire and quantum well box and quantum well fine wire laser - Google Patents

Abstract

PURPOSE:To form a quantum well fine wire and a quantum well box with excellent controllability by a method wherein a step-difference is formed by etching corpuscular beam having directivity, a second semiconductor layer wherein lattice unconformity between a first semiconductor and the second semiconductor is made larger than or equal to a specified value is grown on the step-difference part, and the first semiconductor layer is grown on a substrate. CONSTITUTION:The lattice unconformity 1 between a first and a second semiconductors ¦(lattice constant of the first semiconductor)-(lattice constant of the second semiconductor)¦/(lattice constant of the first semiconductor) is made 10<-2> or more. By utilizing the GaAs substrate face orientation dependency on the growth speed of GaAs and InAs, an InAs layer 11 is selectively grown only on a step-difference part on a GaAs substrate 4 of (111) face wherein the step-difference having (100) face is formed, by corpuscular beam epitaxy. In the similar manner to the InAs growth, a GaAs layer 13 is grown on the GaAs substrate 4 by corpuscular epitaxy. Hence, the GaAs layer 13 is grown with almost the same growth speed on the whole surface of the GaAs substrate, and is grown on also the InAs layer 11 with almost the same growth speed as the growth speed. Thereby, the InAs layer 11 can be filled with the GaAs layer 13, and a quantum well fine wire 2 composed of the layer 11 can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a quantum well wire used in a semiconductor device, a method for manufacturing a quantum well box, and a quantum well wire laser using the quantum well wire as a light emitting region. It is.

Background of the Invention In recent years, there has been a demand for improved characteristics and functions of semiconductor devices, such as a reduction in the threshold current of semiconductor lasers, an improvement in temperature characteristics, a reduction in spectral line width, and an increase in the speed of FET devices. 2. Description of the Related Art Semiconductor devices using a quantum well structure (two-dimensional electronic system) in which ultra-thin films having gaps are alternately stacked are being actively developed in various fields. Figure 5 (-) is a conceptual diagram of the quantum well structure.
FIG. 5(b) is a characteristic diagram showing the density of states. Quantum well structure 1 includes potential barrier 100 and quantum well 110
Consisting of Figure 50 is a conceptual diagram of a quantum well thin wire, Figure 5) is a characteristic diagram showing its density of states, Figure 7 (a) is a conceptual diagram of a quantum well box, and Figure 7 (b) is its state. It is a characteristic diagram showing density. Quantum well structure 1 to quantum well thin wire 2. The degree of freedom of electrons decreases in the order of the quantum well box 3, and the density of states becomes sharper. Therefore, the quantum well thin wire 2 (one-dimensional electronic system) and the quantum well box 3 (O-dimensional electronic system), which further improve the characteristic 1 function of the quantum well structure 1, have been attracting attention, and semiconductor lasers etc. using these have been proposed. (Solid State Physics 22 (1987), pp. 71-82).

Currently, a method for manufacturing the quantum well thin wire 2 and the quantum well box 3 has not been established, but the following method is used. FIG. 8 is a process diagram showing a conventional method for manufacturing the quantum well thin wire 2. As shown in FIG. As shown in FIG. 8(,), an InAs layer 5 serving as a quantum well layer is formed on a GaAs substrate 4
A laminated structure including a GaAs layer 6 serving as a potential barrier layer having a larger energy gap than layer 5 is formed. Next, grooves 7 are formed by etching as shown in FIG. 8(b). At this time, the minimum dimension of dl is determined by the minimum dimension of phosphorography or the beam diameter of a focused ion beam for direct writing. This minimum dimension is approximately 0.1 μm. Furthermore, in order to obtain a dl smaller than about 0.1 μm, there is a method of utilizing side etching in wet etching. As shown in FIG. 8(C), the groove 7 is filled with the G a A B layer e to form a quantum well-like laminated structure, and this is etched to form a stacked structure as shown in FIG. 9(b).
) A groove 7 is formed as shown in FIG. d2 at this time. d3
The minimum dimension of is determined in the same manner as the minimum dimension of dl in FIG. 8(b), and the minimum dimension is approximately 0.1 μm.

Next, as shown in FIG. 9(C), a quantum well box 3 is obtained by the same embedding process as in FIG. 8(C).

Problems to be Solved by the Invention However, in the conventional manufacturing method of the quantum well thin wire 2 and the quantum well box 3, the minimum horizontal dimension on the substrate is the minimum dimension of phosphorography or the beam diameter of the focused ion beam for direct writing. The determined tb, D value is approximately 0.1 μm.

The characteristics and functions of the quantum well thin wire 2 and the quantum well box 3 have a limit because they can only be improved if the D value is small (several 1008 or less). In addition, to obtain a value as small as about 0.1 μm, there is a method of using side etching in wet etching, but if uneven etching occurs depending on the amount of etching solution applied, stable etching speeds of 1000 or less 8 layers are not possible. This method had poor dimensional control, as it was difficult to obtain an etching solution with a

The present invention has been made in view of the above-mentioned problems, and proposes a method for manufacturing quantum well wires 2 and quantum well boxes 3 having dimensions smaller than the current minimum dimension of about 0.1 μm with good controllability. The purpose is to

Furthermore, regarding the semiconductor laser using the quantum well wire 2 (one-dimensional electronic system), there has been no proposal for a quantum well wire laser that is specific and easy to manufacture. Another object of the present invention is to provide a quantum well wire laser that uses a quantum well wire as an active layer, which is specific and easy to manufacture.

Means for Rounding to Solve the Problems In order to solve the above-mentioned problems, the present invention aims to solve the above-mentioned problems by providing a method for manufacturing quantum well thin wires having a (111) surface or the (111) surface.
11) forming a step formed by a (100) plane or a plane equivalent to the (100) plane on a substrate made of a first semiconductor which is a plane equivalent to the (100) plane by etching with a directional particle beam; A lattice mismatch 1 (lattice constant of the first semiconductor) - (lattice constant of the second semiconductor) |/(lattice constant of the first semiconductor) between the first semiconductor and the second semiconductor is formed in the stepped portion of the substrate. The method comprises the steps of growing the second semiconductor layer having a lattice constant (lattice constant) of 10@-2 or more, and growing the first semiconductor layer on the substrate.

In addition, for manufacturing a quantum well box, a substrate made of a first semiconductor whose surface is a (111) plane or a plane equivalent to the (111) plane is coated with a (100) plane or the (100) plane.
a step of forming a step consisting of a plane equivalent to a plane and a non-(1QO) plane by etching with a directional particle beam; Matching 1 (lattice constant of the first semiconductor) - (second
(lattice constant of the first semiconductor) |/(lattice constant of the first semiconductor)
The method comprises the steps of growing a layer of the second semiconductor having a thickness of 10 or more, and a step of growing a layer of the first semiconductor on the substrate.

Another invention provides a GaAs substrate whose surface is a (111) plane or a plane equivalent to the (111) plane, and a GaAs substrate formed on the GaAs substrate to solve the above-mentioned problems. a first cladding layer formed on the first cladding layer, the interface between the GaAs layer and the InAs quantum well wire is at least in the (100) plane or in the (100) plane;
a second active layer formed on the active layer;
This is a quantum well thin wire laser with a structure consisting of a cladding layer.

Effect of the present invention The surface is (111) or (111)
Since a directional particle beam is used as a means for forming a step consisting of a (100) plane or a plane equivalent to the (100) plane on the first semiconductor substrate, which is a plane equivalent to the (100) plane,
By simply keeping the irradiation direction of the particle beam at a certain angle, steps of several hundred or less can be obtained with good controllability. Good controllability can also be obtained for a step formed by a (100) plane or a plane equivalent to the (100) plane and a non-(100) plane.

In addition, when growing a first semiconductor layer or a second semiconductor layer on a first semiconductor substrate, the growth of the first semiconductor layer is performed approximately with respect to the surface of the substrate with either plane orientation. While the single crystal of the first semiconductor layer grows at the same growth rate, the lattice mismatch in the growth of the second semiconductor layer is 10-2 or more.
The single crystal of the second semiconductor layer grows at the fastest growth rate on the (100) plane, and the plane orientation of the substrate surface is (100).
) There is a phenomenon in which the growth rate rapidly decreases as the surface deviates from the plane. The present invention utilizing this phenomenon is (1o○)
If a second semiconductor layer and a first semiconductor layer are grown on a substrate made of a first semiconductor having a (111) plane with a step formed by a plane, a layer of the second semiconductor and a first semiconductor layer are grown on the (100) plane. Only the second semiconductor layer can be selectively grown;
A layer of semiconductor may be embedded with the layer of first semiconductor.

Another invention is that an active layer having a width of several hundred or less quantum well wires can be produced with good control using the method for manufacturing quantum well wires described above. GaAs still consists of (111) surface
Since the substrate has a step formed of at least the (100) plane, the plane of the quantum well thin wire becomes the (oll) plane or an equivalent plane, and the resonator can be easily formed by cleavage. Furthermore, in the combination of InAs and Ga As, for example, Ga As and AI x Ga 1
Since it has a large energy gap difference of 1.1 eV compared to a combination of -, As, etc., the characteristics of the semiconductor laser due to the quantum well effect are considerably improved, and the emission wavelength range can be widened.

Example (Example 1) FIG. 1 shows a process diagram of a method for manufacturing a quantum well thin wire according to an example of the present invention. As shown in FIG. 1(a), on a GaAs substrate 4 whose surface is a (711) plane,
An etching mask 8 having a linear opening end along the [011] direction is formed. As the mask 8, S 1
02 thin film, resist, etc. can be used. Next, Cl
Etching is performed using a particle beam such as an ion beam 300. As shown in Figure 1), the inclination angle θ of the particle beam
is the (11
1) Set the distance from the normal direction of the surface to 36 degrees around the cloth on the paper surface of Figure 1. Thereby, a step 200 whose etched side surface is a (100) plane can be formed on the GaAs substrate 4.

Width D1 of the etch side surface, which becomes the width of the quantum well thin line in a later process
is determined uniquely from the etch rate in particle beam etching, and a value of several hundred Å or less can be easily obtained with good controllability. For example, 600 people/mm for Ga As
If you use the etch speed of 30 seconds, G
250 said widths were obtained on the aAs substrate 4.

As shown in FIG. 3, the G a A s using the molecular beam epitaxial growth method and the G a A
sSubstrate surface orientation dependence. As the G a A g substrate plane orientation deviates from the (100) plane, the growth rate of InAs decreases rapidly, and the growth rate of InAs decreases to the (311) plane.

Almost no growth was observed on the (111) plane. On the other hand, the growth rate of GaAs was almost constant for any surface orientation. The growth conditions at this time were: growth temperature 550°C, A84/In7 lux ratio 6, As4
The pressure (flux amount) is 2×10-” Torr.

Generally, the lattice mismatch 1 (
When the ratio (lattice constant of the first semiconductor)−(lattice constant of the second semiconductor) l/(lattice constant of the first semiconductor) is 10 −2 or more, the above phenomenon is observed. G a As and In
Utilizing the dependence of the As growth rate on the Ga As substrate surface orientation, the Ga As substrate with the (111) plane provided with a step having the (100) plane was grown as shown in FIG. 1(c). 4
InAgnAg was deposited on top by molecular beam epitaxial growth method.
Selective growth can be performed only on all 11 parts.

In order to grow all 11 InAsnAs, atomic beam In9 made from metal In and molecular beam AB410 made from metal arsenic were used as raw materials.

Next, as shown in FIG. 1(d), molecular beam epitaxial growth is used, similar to InAs growth! 1lGaAs layer 13
When grown on the G a A s substrate 4, G a A
As shown in FIG. 3, the S layer 13 has Ga on all sides.
It grows at almost the same growth rate as the InA substrate.
Since the InAs layer 11 can be buried with the GaAs layer 13 because it grows on snAs at almost the same growth rate as the growth rate described above, the quantum well thin wire 2 made of the layer 11 can be formed. In order to grow the GaAs layer 13, an atomic beam Ga12 made from metal Ga is used as a raw material.
A molecular beam AB410 made from metal arsenic and metal arsenic was used. Further, by repeating the steps of FIG. 1(C) and FIG. 1(d) nine times, a multilayer structure of the quantum well thin wire 2 can be formed, and I n A s is compared to G a A s. Since the energy gap is small, InAs is used as a quantum well layer.

A thin quantum well wire can be formed using GaAs as a potential barrier layer. In this example, InAs is grown.

Although G a A g growth was performed using a particle beam typified by molecular beam epitaxial growth, it may also be performed using non-equilibrium vapor phase growth typified by organometallic vapor phase growth. Further, instead of the molecular beam A s 4, A a 2 may be used.

(Example 2) FIG. 2 shows a process diagram of a method for manufacturing a quantum well box in an example of the present invention. As shown in Figure 2(a), (11
1) On the G a A g substrate 4 consisting of the surface, [o11
] An etching mask 14 is formed having an opening end in the shape of a sine wave or a sawtooth wave along the direction. mask 14
As the material, S102 thin film, resist, etc. can be used. As shown in Figure 2), etching with a particle beam such as a C1 ion beam 300 similar to that in Figure 1) is performed to form a step with the etched side surface consisting of a (100) plane and a non-(10o) plane. It can be formed on the aAs substrate 4.

The width D2 of the etched side surface, which becomes one width of the quantum well box in the later process, is uniquely determined from the etch rate in particle beam etching, similar to the width D1, and a value of several hundred or less can be easily controlled with good controllability. can be obtained. On the other hand, the cross-sectional shape of the InAs layer 11 perpendicular to the direction of the width D3 of the quantum well box is determined by the shape of the opening end of the mask 14. The width D3 of the quantum well box depends, for example, on the radius of curvature at the (100) tangent surface A, and the larger the radius of curvature, the longer D3 becomes. The width D4 of the quantum well box can be determined by the growth time of InAs. As shown in FIG. 2(c), the InAs layer 11 is selectively grown in the same manner as in the step of FIG. 1(c). Next, as shown in FIG. 2(d), a GaAs layer 13 can be formed in the same manner as in the step of FIG. 1(d). Further, by repeating the steps shown in FIG. 2(C) and FIG. 2(d), a multilayer structure of the quantum well box 3 can be formed.

(Example 3) FIG. 4 shows a process diagram of a method for manufacturing a quantum well thin wire laser according to an example of the present invention. As shown in FIG. 4(a), an n-type GaAs substrate 15 having a (111) surface
A first cladding layer of n-type AlGaAs 16 is grown thereon. As shown in FIG. 4(b), G a A
The s-layer 17 is grown. Next, by performing the steps shown in FIGS. 1(a) to 1(d), an active layer 19 having a single, discrete InAs quantum well thin wire 18 as shown in FIG. 4(c) is obtained. Furthermore, if the steps in Fig. 1(C) and (d) are repeated twice, a group as shown in Fig. 4(d) is formed, and a discrete I
An active layer 20 having nAs quantum well wires 18 is obtained.

Next, as shown in Fig. 4(,), the p-type A I G a A
Grow a second cladding layer consisting of s21 and AlZn
When a p-type electrode made of 22 and an n-type electrode made of AuGe 23 are formed, a first
cladding layer, InAs quantum well wire 18 and Ga
Active layer 19 consisting of As layer 17. A quantum well thin wire laser in which the second cladding layer is laminated is obtained.

In addition, a GaAs substrate 15 having a (111) surface
Since there is a step formed by the (10o) plane on the top, In
The step plane of the As quantum well wire 18 becomes an (oll) plane or an equivalent plane, and a resonator can be easily formed by cleaving. In this embodiment, a GaAs substrate, an InAs quantum well thin wire, and an AlGaAs cladding layer are used, but the combinations shown in the table below may be used.

Effects of the Invention As is clear from the above description, the present invention provides a first semiconductor substrate whose surface is a (111) plane, and a side surface of which is a (10) plane.
o) Since a directional particle beam is used as the means for forming the step, a step of several hundred or less can be obtained with good controllability simply by keeping the irradiation direction of the particle beam at a certain angle. Good controllability can also be obtained for a step formed from the (10o) plane or the above-mentioned (100) plane, a special plane, or a non-(100) plane. In addition, when growing a second semiconductor or a layer of the first semiconductor on a substrate made of a first semiconductor, the growth of the first semiconductor layer has approximately the same orientation with respect to the surface of the substrate having either plane orientation. Whereas the single crystal of the first semiconductor layer grows at a growth rate, the growth rate of the second semiconductor layer is fastest on the (100) plane of the substrate surface because the lattice mismatch is 10 or more. There is a phenomenon in which the single crystal of the second semiconductor layer grows at a certain growth rate, and the growth rate rapidly decreases as the plane orientation of the substrate surface deviates from the (100) plane. The present invention, which utilizes this phenomenon, (
If a second semiconductor layer and a first semiconductor layer are grown on a substrate made of a first semiconductor having a (111) plane with a step formed by a (100) plane, the (100) plane A second semiconductor layer can be selectively grown only on the top,
The second semiconductor layer can be embedded with the first semiconductor layer.

Another advantage is that by using the above-described method for manufacturing quantum well wires, active layers having a width of several hundred or less quantum well wires can be fabricated with good controllability. Also, GaA consisting of (111) surface
Since the s-substrate has a step formed of at least a (100) plane, the cross section of the quantum well thin wire becomes a (011) plane or an equivalent plane, and a resonator can be easily formed by cleavage. Furthermore, in the combination of InAs and GaAs, for example, GaAs and A1
Since it has a large energy gap difference of 1.1 eV compared to a combination such as -xAs, the characteristics of the semiconductor laser due to the quantum well effect are considerably improved, and the emission wavelength range can be widened.

[Brief explanation of the drawing]

FIGS. 1(a) to (d) are process diagrams showing a method for manufacturing a quantum well thin wire according to an embodiment of the present invention, and FIGS. 2(a) to (d)
) is a process diagram showing a method for manufacturing a quantum well box in an embodiment of the present invention, FIG. 3 is a characteristic diagram showing the dependence of GaAg and InAs growth rate on GaAs substrate surface orientation, and FIG. (,) to (,) are process diagrams showing a method for manufacturing a quantum well thin wire laser in an embodiment of the present invention, FIG. 5(-) is a conceptual diagram of the quantum well structure, and FIG. 5(b) is a quantum well Characteristic diagram showing the density of states of the structure. Figure 5 (,) is a conceptual diagram of a quantum well wire. Figure 5 (b) is a characteristic diagram showing the density of states of a quantum well wire. Figure 7 (,) is a diagram of a quantum well wire. Conceptual diagram of the box, Figure 7 (
b) is a characteristic diagram showing the density of states of a quantum well box, and Fig. 8(a)
) to (C) are process diagrams showing a conventional method for manufacturing a quantum well thin wire, and FIGS. 9(a) to (C) are process diagrams showing a conventional method for manufacturing a quantum well box. 2...Quantum well thin wire, 3...Quantum well box, 4...GaAs substrate, 8,14...
...Etching mask, 9...In, 10.
...As4.11 ...InAs layer, 12
・++−++Ga, 13.17===GaAs layer, 1
5 ・-・-・-n-type GaAs substrate, 16-・-n-type A
lGaAs, 18...InAg quantum well thin wire, 19.20...Active layer, 21 =--p type AIGaAs, 22-=・AuZn, 2
3...AuGe0 Name of agent Patent attorney Shigetaka Awano and 1 other person
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Claims (9)

[Claims] (1) On a substrate made of a first semiconductor whose surface is a (111) plane or a plane equivalent to the (111) plane,
) plane or a plane equivalent to the (100) plane by etching with a directional particle beam, and forming a lattice of the first semiconductor and the second semiconductor in the step part of the substrate. Mismatch | (lattice constant of first semiconductor) −
(lattice constant of the second semiconductor) |/(lattice constant of the first semiconductor) of growing the second semiconductor layer of 10^-^2 or more; A method for manufacturing a quantum well thin wire, which consists of a step of growing a semiconductor layer. The method for manufacturing a quantum well thin wire according to claim 1, which comprises the step of (2) growing the second semiconductor layer using a particle beam typified by molecular beam epitaxial growth. (3) The method for manufacturing a quantum well thin wire according to claim 1, which comprises the step of growing the second semiconductor layer using non-equilibrium vapor phase epitaxy typified by organometallic vapor phase epitaxy. (4) The method for manufacturing a quantum well thin wire according to claim 1, wherein the first semiconductor is GaAs and the second semiconductor is InAs. (5) On a substrate made of a first semiconductor whose surface is a (111) plane or a plane equivalent to the (111) plane,
) plane or a plane equivalent to the (100) plane and non-(1
00) plane by etching with a directional particle beam, and forming a lattice mismatch between the first semiconductor and the second semiconductor in the step part of the substrate. lattice constant) - (lattice constant of second semiconductor) |/
A quantum well comprising a step of growing a layer of the second semiconductor whose lattice constant (lattice constant of the first semiconductor) is 10^-^2 or more, and a step of growing a layer of the first semiconductor on the substrate. How to make a box. (6) The method for manufacturing a quantum well box according to claim 5, which comprises the step of growing the second semiconductor layer using a particle beam typified by molecular beam epitaxial growth. (7) The method for manufacturing a quantum well box according to claim 5, which comprises the step of growing the second semiconductor layer using non-equilibrium vapor phase epitaxy typified by organometallic vapor phase epitaxy. (8) The method for manufacturing a quantum well box according to claim 5, wherein the first semiconductor is GaAs and the second semiconductor is InAs. (9) a GaAs substrate whose surface is a (111) plane or a plane equivalent to the (111) plane, a first cladding layer formed on the GaAs substrate, and a GaAs substrate formed on the first cladding layer; an active layer consisting of the GaAs layer and the InAs quantum well wire embedded in the GaAs layer, wherein the interface between the layer and the InAs quantum well wire is at least a (100) plane or a plane equivalent to the (100) plane; A quantum well thin wire laser consisting of a second cladding layer formed on top of the second cladding layer.