JP2000021671A - Manufacture of magneto-optical device and the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a magneto-optical device, using magneto-optical effect, which can be integrated with a semiconductor optical device by forming a magnetic body particulate/semiconductor compound material and stacking the compound material on a semiconductor substrate by combining a crystal growing method, which has strong non-balance growth conditions and a heat treatment after the growth and the magnet-optical device. SOLUTION: On a semiconductor substrate 1, a magnetic mixed crystal semiconductor 3 is formed through epitaxial growth across a semiconductor layer 2, and a heat treatment is carried out in or after the epitaxial growth to form a magnetic body particulate/semiconductor compound material 4, having ferromagnetic particulates embedded in the semiconductor. This process is repeated to form a multilayered heterostructure which includes a magnetic body particulate/semiconductor compound structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magneto-optical device (magneto-optical device) using a magnetic fine particle / semiconductor composite material and a magneto-optical device thereof.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there has been a proposal disclosed by the present inventors as disclosed below. [1] Masaaki Tanaka, Minoru Hayashi, Akira Nishinaga, Hiroshi Shimada “II
Epitaxial growth and magnetic and electric conduction characteristics of Group IV diluted magnetic semiconductor GaMnAs "Journal of the Japan Society of Applied Magnetics, 21,
pp. 393-396 (1997). [2] T.I. Hayashi, M .; Tanaka, T .; N
ishinaga and H .; Shimada "Ga
MnAs: New III-V Based Diluted
Magnetic Semiconductors
GROWN BY MOLECULAR BEAM E
pitxy "J. of Crystal Growth
h 175/176 pp. 1063-1068 (19
97). [3] Masaaki Tanaka "Epitaxi
al Ferromagnetic Thin Film
ms and Heterostructures o
f Mn-based Metallic and S
emiconing Compounds o
n GaAs ", Institute of Select
Rikal Engineers of Japan,
MAG97-189, pp. 31-38, Ryukyu
University, November 199
7. [Masaaki Tanaka “Formation of Magnetic / Semiconductor Hybrid Structure and Its Physical Properties” IEICE Magnetics Research Group, MA
G-97-189, pp. 31-38, University of the Ryukyus, 19
November 1997] Both the above-mentioned papers [1] and [2] describe a method of manufacturing a magnetic semiconductor (GaMn) As, its structure evaluation, electric conduction, magnetic properties, and the like.

In addition, the above-mentioned paper [3] describes a method of manufacturing a superlattice composed of a magnetic semiconductor (GaMn) As / a non-magnetic semiconductor (AlAs), a structure evaluation, electric conduction, and magnetic properties.

[0004]

The inventor of the present application has further developed a superlattice composed of a magnetic semiconductor (GaMn) As / non-magnetic semiconductor (AlAs) as described above to use a magnetic fine particle / semiconductor composite material. Was developed. In view of the above situation, the present invention forms a magnetic fine particle / semiconductor composite material by combining a crystal growth method having a strong non-equilibrium growth condition and a heat treatment after growth, and laminates this composite material on a semiconductor substrate. Accordingly, an object of the present invention is to provide a method of manufacturing a magneto-optical device using a magneto-optical effect that can be integrated with a semiconductor optical device, and a magneto-optical device thereof.

[0005]

According to the present invention, there is provided a method for manufacturing a magneto-optical device, comprising: a step of epitaxially growing a magnetic mixed crystal semiconductor on a semiconductor substrate via a semiconductor layer; And performing a heat treatment during or after the epitaxial growth to form a magnetic fine particle / semiconductor composite material in which ferromagnetic fine particles are embedded in a semiconductor.

[2] In the method of manufacturing a magneto-optical device according to the above [1], the epitaxial growth is performed by a crystal growth method having strong non-equilibrium growth conditions. [3] In the method for manufacturing a magneto-optical device according to the above [2], the crystal growth method is a low-temperature growth molecular beam epitaxy method. [4] The method for manufacturing a magneto-optical device according to [1], wherein a large amount of magnetic ions are dissolved in the semiconductor by the epitaxial growth.

[5] In the method for manufacturing a magneto-optical device according to the above [1], the size of the magnetic fine particles can be controlled by the concentration of magnetic ions and the heat treatment temperature. [6] In the method for manufacturing a magneto-optical device according to the above [5], the magnetic fine particle / semiconductor composite material has properties of a semiconductor and a ferromagnetic material, and can control the magneto-optical characteristics at room temperature. .

[7] In the magneto-optical device, a magneto-optical layer having a magnetic fine particle / semiconductor composite material is inserted at an interface between a semiconductor layer having a low refractive index and a semiconductor optical waveguide layer having a high refractive index or in the waveguide layer. Due to the refractive index difference, light is confined in the semiconductor optical waveguide layer and becomes a waveguide, but the Faraday effect is generated by the magneto-optical layer having the magnetic fine particles / semiconductor composite material having a strong magneto-optical effect. It was made.

[8] In the magneto-optical device, at the interface between the semiconductor layer having a low refractive index and the semiconductor optical waveguide layer having a high refractive index,
A magneto-optical layer having a magnetic fine particle / semiconductor composite material is inserted, and light is confined in the semiconductor optical waveguide layer due to the difference in refractive index to become a waveguide, but the magnetic fine particle / semiconductor having a strong magneto-optical effect A magneto-optical layer having a composite material is connected to an output-side waveguide of a semiconductor laser to be integrated, and is made of a semiconductor light emitting element whose wavelength is tunable by a magnetic field.
For a semiconductor device whose emission wavelength can be varied by a magnetic field, for example, by inserting magnetic fine particles / semiconductor composite material near the active layer of a semiconductor laser, the oscillation wavelength can be changed by an external magnetic field through the large magneto-optical effect of this layer. Is made possible.

According to the present invention, as described above, a magnetic fine particle / semiconductor composite material can be formed by combining a crystal growth method having strong non-equilibrium growth conditions with annealing after growth. It has been found that a new magneto-optical device such as a device using the magneto-optical effect and a high-performance non-reciprocal optical device can be obtained by integrating the composite material with a semiconductor. In particular, a magneto-optical device having a high degree of freedom in design has been made possible by a semiconductor heterostructure including magnetic fine particles at an arbitrary position. These new devices have unprecedented features such as being operable at room temperature and being able to be integrated with conventional semiconductor optical devices.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a manufacturing process of a magneto-optical device using a magnetic fine particle / semiconductor composite material according to an embodiment of the present invention. (1) First, as shown in FIG. 1A, a magnetic mixed crystal semiconductor 3 is epitaxially grown on a semiconductor substrate 1 via a semiconductor layer 2.

Here, the epitaxial growth of the magnetic mixed crystal semiconductor layer is performed by a crystal growth method having a strong non-equilibrium growth condition (for example, a low temperature growth molecular beam epitaxy method). That is, a crystal growth method having strong non-equilibrium growth conditions (for example,
Si, Ga by low-temperature growth molecular beam epitaxy)
A large amount of magnetic ions (Fe, Mn, Co, Ni, etc.) are dissolved in a semiconductor such as As, InP, InGaAs or the like.

Under such strong non-equilibrium growth conditions, a new mixed crystal semiconductor in which a large amount of magnetic ions (several%) having a concentration exceeding the solid solution limit (about 0.01%) is mixed in the semiconductor. Can be produced. (2) Next, annealing (heat treatment) during or after growth
As a result, as shown in FIG. 1B, the magnetic fine particles / semiconductor composite material 4 is formed on the semiconductor substrate 1 and the semiconductor layer 2.
To form

By this heat treatment, the magnetic element existing as a single atom (or ion) in the semiconductor becomes a fine particle of a ferromagnetic compound by taking in some of the constituent elements of the semiconductor. That is, a magnetic fine particle-semiconductor composite material system in which ferromagnetic fine particles are embedded in a semiconductor can be produced. The size of the ferromagnetic fine particles can be controlled by the original concentration of magnetic ions and the heat treatment temperature (300 ° C. to 800 ° C.). For example, in the case of a composite material system composed of GaAs-MnAs fine particles, it can be varied from about 1 nm to about several μm.

By repeating the process shown in FIGS. 1A and 1B, a multilayer composite material containing magnetic fine particles at an arbitrary position as shown in FIG. 1C is formed. You can also. The crystallinity and magnetic characteristics of a magneto-optical device using the magnetic fine particles / semiconductor composite material manufactured in this manner will be described.

FIG. 2 is a graph showing the single crystallinity of the semiconductor and the magnetic fine particles in the composite structure of the magneto-optical device of the present invention.
It is a line diffraction spectrum characteristic view. In this figure, the horizontal axis is 2θ (θ is the incident angle of X-rays), and the vertical axis is X-ray diffraction intensity (relative unit). As is clear from this figure, it is clear that both the semiconductor and the magnetic fine particles in the composite structure maintain good single crystallinity.

In the magnetic fine particle-semiconductor composite material system, the value of the saturation magnetization is increased by changing the temperature and time of annealing (heat treatment), so that the magnetic characteristics can be significantly changed. FIG. 3 shows an embodiment of the present invention before and after heat treatment of a magnetic mixed crystal semiconductor (GaAs) Mn and MnA.
FIG. 4 is a diagram illustrating an example of magnetization characteristics at room temperature after heat treatment of s-magnetic fine particles.

As is apparent from this figure, the heat treatment of the MnAs magnetic fine particles can improve the magnetization characteristics. Further, the magneto-optical effect can be greatly changed. FIG. 4 shows magnetic circular dichroism (Magnetic circular dichroic) of MnAs magnetic fine particles embedded in a GaAs matrix showing an embodiment of the present invention.
FIG. 2 is a diagram showing a spectrum of ism, MCD). Here, the horizontal axis is photon energy (eV), and the vertical axis is MCD (m
deg).

As shown in the figure, comparing the spectra of magnetic circular dichroism (MCD) measured using the reflected light, both the spectral shape and the intensity greatly change.
Therefore, by changing the manufacturing conditions, it is possible not only to change the structure, but also to change (control) the magnetic properties and the magneto-optical effect at room temperature.

As described above, it is a characteristic of this material system to have both the properties of a semiconductor and a ferromagnetic material and to be able to control the magnetic and magneto-optical properties at room temperature. On the other hand, in the conventional magnetic semiconductor, since the ferromagnetic transition temperature is low, it is not possible to control the magneto-optical characteristics at room temperature. Next, a new magneto-optical device using a heterostructure will be described.

In a conventional non-magnetic semiconductor material, a superlattice / heterostructure can be manufactured by using a crystal growth technique such as molecular beam epitaxy having a film thickness controllability at an atomic level. The above-mentioned magnetic fine particle-semiconductor composite material system has extremely good crystallinity, and is manufactured using epitaxial growth. Therefore, a heterostructure or a superlattice can be easily manufactured, and a semiconductor heterostructure in which magnetism strongly appears at room temperature. Can be formed.

The method for fabricating the semiconductor heterostructure is as follows. First, a heterostructure composed of a nonmagnetic semiconductor and a magnetic mixed crystal semiconductor is grown using non-equilibrium crystal growth such as low-temperature molecular beam epitaxy. Magnetic fine particles are formed only in the portion of the mixed crystal semiconductor. Since the magnetic fine particles do not diffuse and move in the crystal,
A semiconductor heterostructure containing magnetic fine particles at an arbitrary position is formed.

As a result, a new degree of freedom of magnetism (or spin effect) can be brought to the world of a semiconductor heterostructure originally made of a nonmagnetic material (at room temperature), and various devices can be provided. Application becomes possible. Hereinafter, a device application example using such a magnetic fine particle / semiconductor composite material system will be described.

Magnetic fine particles-semiconductor composite material (Fer
romantic Particles-Semi
conductor Hybrid Material
s, here simply referred to as FP-S for simplicity). (1) Faraday rotator having a waveguide structure FIG. 5 is a schematic view of a Faraday rotator having a waveguide structure according to an embodiment of the present invention. FIG. (B) is a sectional view showing a modified example thereof.

As shown in FIG. 5A, FP-S (eg, GaAs) is formed at the interface between the semiconductor layer 11 (eg, AlGaAs) having a low refractive index and the semiconductor optical waveguide layer 13 (eg, GaAs, InGaAs) having a high refractive index. GaAs-MnAs) layer 1
Insert 2. Due to the refractive index difference, light is confined in the semiconductor waveguide layer 13 and becomes a waveguide having a light intensity distribution as shown in 14, but the Faraday effect is reduced by the influence of the FP-S layer 12 having a strong magneto-optical effect. Occurs. FP-
By inserting the S layer 12 at the interface between the semiconductor layer 11 having a low refractive index and the semiconductor optical waveguide layer 13 having a high refractive index, a structure in which an increase in loss is prevented.

As shown in FIG. 5 (b), very thin (about several nm) FP-S layers 12A, 12B, 12C, 12D,.
Is inserted several layers. Light is confined in the semiconductor optical waveguide layer 13 and becomes a waveguide having a light intensity distribution shown in FIG. 14 as in FIG.
The Faraday effect occurs due to the influence of the S layer. The loss is prevented by making the thickness of each FP-S layer very thin, and the Faraday effect is increased by using several layers in the waveguide.

The features of the Faraday rotator having this waveguide structure are a waveguide including a magnetic material formed on a semiconductor substrate, and have excellent matching with a conventional semiconductor optical device, and a thickness of each layer. The degree of freedom in design, such as the composition, composition, and concentration of the magnetic substance, is large, and a large Faraday effect can be expected even at room temperature. (2) Optical Isolator FIG. 6 is a perspective view showing an optical isolator integrated on the same substrate as the optical device according to the embodiment of the present invention.
(A) is a perspective view of the ridge waveguide device, and FIG.
(B) is a perspective view of the embedded waveguide device.

As shown in these figures, the semiconductor laser 2
Same substrate 20A, 20B as optical device such as 1A, 21B
Waveguide-type optical isolators 22A and 22B composed of Faraday rotators connected to the output waveguides of the semiconductor lasers 21A and 21B integrated above are provided. in this way,
A small optical isolator can be manufactured over a semiconductor substrate.

Conventionally, the isolator is a component completely separate from the semiconductor laser. However, according to this embodiment, the integration can be downsized and the cost can be reduced. (3) Semiconductor Light Emitting Device Variable in Wavelength by Magnetic Field FIG. 7 is a schematic view of a semiconductor light emitting device variable in wavelength by a magnetic field according to an embodiment of the present invention. Note that the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in this figure, by embedding the FP-S layer 32 near the active layer 31 of the semiconductor laser,
The oscillation wavelength can be controlled through the magneto-optical effect. The light emission of the semiconductor laser propagates through the waveguide, but is affected by the FP-S layer 32 at that time, and the wavelength shifts in proportion to the magnetization of the FP-S layer 32. Since the magnetization of the FP-S layer 32 can be continuously changed by the applied magnetic field, the oscillation wavelength of the laser can be controlled by an external magnetic field. That is, a semiconductor laser having a variable wavelength can be obtained.

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

[0032]

As described above, according to the present invention, the following effects can be obtained. (A) The functions can be combined. That is, characteristics of completely different materials such as a magnetic material and a semiconductor can be combined. The magnetic particles / semiconductor composite material
It has both functions of magnetic material and semiconductor.

(B) Good crystallinity. That is, it is a material system composed entirely of single crystals and has few structural defects. (C) Structural control at the atomic level. That is, structural parameters such as film thickness and fine particle size can be controlled at the atomic level. (D) Various device applications are possible. That is, it can be applied to a device using a magneto-optical effect that can be integrated with a semiconductor and a high-performance non-reciprocal optical device. In particular, by combining with a semiconductor heterostructure, the design flexibility of this composite material system is greatly expanded.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a magneto-optical device using a magnetic fine particle / semiconductor composite material according to an embodiment of the present invention.

FIG. 2 is an X-ray diffraction spectrum characteristic diagram showing single crystallinity of a semiconductor and magnetic fine particles in a composite structure of the magneto-optical device of the present invention.

FIG. 3 shows a magnetic mixed crystal semiconductor (GaAs) showing an embodiment of the present invention.
s) An example of magnetization characteristics at room temperature before heat treatment of Mn and after heat treatment of MnAs magnetic fine particles.

FIG. 4 is a view showing a magnetic circular dichroism (MCD) spectrum of MnAs magnetic fine particles embedded in a GaAs matrix showing an example of the present invention.

FIG. 5 is a schematic view of a Faraday rotator having a waveguide structure according to an embodiment of the present invention.

FIG. 6 is a perspective view showing an optical isolator integrated on the same substrate as the optical device according to the embodiment of the present invention.

FIG. 7 is a schematic view of a semiconductor light emitting device that can be tuned by a magnetic field according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Semiconductor layer 3 Magnetic mixed crystal semiconductor 4, 32 Magnetic fine particle / semiconductor composite material 11 Semiconductor layer with low refractive index 12, 12A-12D, 32 FP-S layer 13 Semiconductor optical waveguide layer with high refractive index 14 Conduction Light intensity distribution in wave path 20A, 20B Same substrate 21A, 21B Semiconductor laser 22A, 22B Waveguide optical isolator 31 Active layer of semiconductor laser

Claims (8)

[Claims] (A) a semiconductor substrate having a semiconductor layer interposed therebetween;
A step of epitaxially growing a magnetic mixed crystal semiconductor;
(B) forming a magnetic fine particle / semiconductor composite material in which ferromagnetic fine particles are embedded in a semiconductor by performing a heat treatment during or after the epitaxial growth. 2. The method for manufacturing a magneto-optical device according to claim 1, wherein said epitaxial growth is performed by a crystal growth method having a strong non-equilibrium growth condition. 3. The method of manufacturing a magneto-optical device according to claim 2, wherein said crystal growth method is a low-temperature growth molecular beam epitaxy method. 4. The method of manufacturing a magneto-optical device according to claim 1, wherein a large amount of magnetic ions are dissolved in a semiconductor by the epitaxial growth. 5. The method of manufacturing a magneto-optical device according to claim 1, wherein the size of the magnetic fine particles can be controlled by the concentration of magnetic ions and a heat treatment temperature. . 6. The method of manufacturing a magneto-optical device according to claim 5, wherein the magnetic fine particle / semiconductor composite material has properties of a semiconductor and a ferromagnetic material, and can control the magneto-optical characteristics at room temperature. A method for manufacturing a magneto-optical device, comprising: 7. A magneto-optical layer having magnetic fine particles / semiconductor composite material is inserted at an interface between a semiconductor layer having a low refractive index and a semiconductor optical waveguide layer having a high refractive index or in a waveguide layer, and the difference in the refractive index is determined. Wherein the light is confined in the semiconductor optical waveguide layer and becomes a waveguide, but the Faraday effect is generated by the magneto-optical layer having the magnetic fine particles / semiconductor composite material having a strong magneto-optical effect. apparatus. 8. A magneto-optical layer having a magnetic fine particle / semiconductor composite material is inserted at an interface between a semiconductor layer having a low refractive index and a semiconductor optical waveguide layer having a high refractive index. The magneto-optical layer containing the magnetic fine particles / semiconductor composite material having a strong magneto-optical effect is confined in the waveguide layer and becomes a waveguide. A magneto-optical device comprising a variable semiconductor light emitting element.