Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With heterojunction
Reexamination Certificate
1999-08-30
2001-12-04
Chaudhuri, Olik (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With heterojunction
C257S096000, C257S103000, C257S190000, C257S200000
Reexamination Certificate
active
06326645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor photonic device, and more particularly to a semiconductor photonic device comprising group III-V compound semiconductor, such as GaN, InGaN, GaAlN, InGaAlN.
2. Description of the Related Art
As a material for forming a semiconductor photonic device such as light emitting diode (LED) or laser diode (LD) for generating lights from a blue light through an ultraviolet light, there has been known a group III-V compound semiconductor represented by a general formula In
x
Ga
y
Al
z
N (x+y+z=1, 0≦x≦1, 0≦y≦1, 0≦z≦1). Since such kind of compound semiconductor is a direct transition type, it has a high light emitting efficiency. Further, since it is possible to control the wave length of a light being emitted by controlling In concentration, said compound semiconductor has attracted public attention.
Since it is difficult to manufacture a large scale single crystal by using the In
x
Ga
y
Al
z
N when a film of such crystal is to be manufactured, a process called hetero-epitaxial growth is used to grow the crystal on substrates of different materials, in general, it is usual that the crystal is allowed to grow on a C surface sapphire substrate and a Si substrate.
However, since the C surface sapphire substrate and Si substrate do not have a matched lattice with the compound In
x
Ga
y
Al
z
, there is a problem that a large amount of crystal defects having a density of 10
8
/cm
2
-10
11
/cm
2
will occur in the crystals grown on the C surface sapphire or Si substrate. As a result, it is impossible to obtain a crystal film having a good quality and an excellent crystallinity.
Accordingly, it has been suggested that ZnO film be formed as a buffer film on the C surface sapphire substrate and Si substrate. Although it is possible to obtain a good quality ZnO orientated film with the light emitting element obtained by forming an In
x
Ga
y
Al
z
N layer on the C surface sapphire substrate through ZnO film, there is a problem in that such a substrate has to be manufactured with a high cost. Further, with the light emitting element obtained by forming a In
x
Ga
y
Al
z
N layer on the Si substrate through the ZnO film, although such a substrate can be manufactured with a low cost, there is another problem in that it is impossible to obtain a ZnO orientated film with a good quality, whereby it is further impossible to grow a In
x
Ga
y
Al
z
N having an excellent crystallinity on the ZnO film.
SUMMARY OF THE INVENTION
The present invention is directed to a semiconductor photonic device which comprises an excellent In
x
Ga
y
Al
z
N layer formed using a Si substrate. The semiconductor photonic device is characterized in that ZnO film is formed on Si substrate with SiO
2
film interposed therebetween so as to obtain a base substrate, a compound semiconductor layer represented by In
x
Ga
y
Al
z
N (x+y+z=1, 0≦x≦1, 0≦y ≦1, 0≦z≦1) is formed on said base substrate.
According to the experiments conducted by the inventor of the present invention, when SiO
2
film was formed on Si substrate and ZnO film was formed on the SiO
2
film, it was able to obtain ZnO film having a good crystallinity. In particular, when the surface of Si substrate was thermally oxidized slightly and a SiO
2
film (thermally oxidized film) having a thickness of 100 Å is formed on the Si substrate, one could obtain ZnO film having a good crystallinity. In addition, even under a condition where the SiO
2
film has been formed on the surface of the Si substrate by means of a physical deposition such as sputtering, it was still able to obtain a ZnO film having a good crystallinity.
Therefore, according to the present invention, it is possible to grow a ZnO film having a good crystallinity on a cheap Si substrate, and it is also possible to grow an In
x
Ga
y
Al
z
N crystal thereon with the ZnO film serving as a buffer layer. Thus, it has become possible to manufacture with a reduced cost a semiconductor photonic device of In
x
Ga
y
Al
z
N series capable of emitting light from a blue light through an ultraviolet light.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
REFERENCES:
patent: 5815520 (1998-09-01), Furushima
patent: 6015979 (2000-01-01), Sugiura et al.
patent: 6045626 (2000-04-01), Yano et al.
patent: 6168659 (2001-01-01), Yuri et al.
patent: 19931300A1 (1999-07-01), None
patent: 8-075940 (1996-03-01), None
patent: 8-083928 (1996-03-01), None
patent: 08139361A (1996-05-01), None
patent: 9-45960 (1997-02-01), None
patent: 9-045960 (1997-02-01), None
“Growth of ZnO thin films on GaAs by pulsed laser deposition”; V. Craciun, et al.;Thin Solid Films; 259 (1995); 1-4.
“Properties of thick ZnO layers on oxidized silicon”; F. Moeller, et al.; 1994 Ultrasonics Symposium; vol. 1, 94 CH3468-6; ISSN: 1051-0117 Nov. 1-4, 1994; pp. 403-407.
Chaudhuri Olik
Louie Wai-Sing
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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