Coherent light generators – Particular active media – Semiconductor
Reexamination Certificate
2000-04-19
2003-06-10
Davie, James (Department: 2828)
Coherent light generators
Particular active media
Semiconductor
Reexamination Certificate
active
06577662
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor laser, its manufacturing method, semiconductor device and its manufacturing method, especially suitable for use in a ridge —structured semiconductor laser using nitride III-compound semiconductors.
2. Description of the Related Art
Vigorous researches and developments have been made in recent years about semiconductor lasers using nitride III-V compound semiconductors like A1GaInN as being semiconductor lasers capable of emitting light over the blue to ultraviolet regions necessary for realization of higher density of optical discs. In order to realize write type optical discs. optical power at least not less than 20 mW is required. A group of Nakamura et al. reported about fabrication of a high power laser using these kinds of material (Appl. Phys. Lett., 72(1998) 2014, Jpn. J. Appl. Phys., 37(1998)L627). This semiconductor laser has a ridge-shaped stripe, side surfaces of the ridge are protected by an insulating film such as SiO
2
, and its p-side electrode is configured to contact only the part of a p-type contact layer on the top surface of the ridge.
The reported semiconductor laser has practical problems, namely, exhibiting kinks in its optical output-electric current property and an increase of the current immediately after the power supply. Kinks demonstrate that higher mode oscillation occurs along with an increase of the optical output. To suppress it, it is necessary to decrease the. difference in refractive index between the ridge portion and the portion outside the ridge or reduce the stripe width. In this case, however, the portion outside the ridge is SiO
2
or air having a small refractive index. Therefore, it is not easy to change the difference of refractive indices. Reducing the stripe width is attended with difficulties in the process.
On the other hand, the increase of the current immediately after the power supply is considered to be induced by thermal deterioration of the active layer. To prevent it, it is necessary to effectively discharge the heat generated in the active layer. In this structure of the semiconductor laser, however, since the portion of the ridge top surface other than the p-type contact layer surface is covered by SiO
2
having a low heat conductivity, it is difficult to dissipate the heat.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a semiconductor laser capable of suppressing higher mode oscillation during high power output by stably controlling transverse modes and excellent in heat dissipation property, and a manufacturing method thereof.
Another object of the invention is to provide a semiconductor device excellent in heat dissipation property and having a long lifetime, and a manufacturing method thereof.
According to the first aspect of the invention, there is provided a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising:
a buried layer made of A1
x
Ga
1-x
As (0≦×1) to bury opposite sides of the ridge-shaped stripe.
According to the second aspect of the invention, there is provided a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising:
a buried layer made of (A1
x
Ga
1-x
)
y
In
1-x
P (0≦×≦1, 0≦y≦1) to bury opposite sides of the ridge-shaped stripe.
According to the third aspect of the invention, there is provided a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising:
a buried layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) to bury opposite sides of the ridge-shaped
According to the fourth aspect of the invention, there is provided a method for manufacturing a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising the steps of:
making the ridge-shaped stripe; and
growing a buried semiconductor layer made of A1
x
Ga
1-x
As (0≦×≦1) to bury opposite sides of the ridge-shaped stripe.
According to the fifth aspect of the invention, there is provided a method for manufacturing a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising the steps of:
making the ridge-shaped stripe; and
growing a buried semiconductor layer made of (A1
x
Ga
1-x
)
y
In
1-y
P (0≦×≦1, 0≦y≦1) to bury opposite sides of the ridge-shaped stripe.
According to the sixth aspect of the invention, there is provided a method for manufacturing a semiconductor laser having a ridge-shaped stripe and made by using nitride III-V compound semiconductors, comprising the steps of:
making the ridge-shaped stripe; and
growing a buried semiconductor layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) to bury opposite sides of the ridge-shaped stripe.
According to the seventh aspect of the invention, there is provided a semiconductor device having a projection on a nitride III-V compound semiconductor base body, comprising:
a buried semiconductor layer made of A1
x
Ga
1-x
As (0≦×≦1) to bury a portion around the projection.
According to the eighth aspect of the invention, there is provided a semiconductor device having a projection on a nitride III-V compound semiconductor base body, comprising:
a buried semiconductor layer made of (A1
x
Ga
1-x
)
y
In
1-y
P (0≦×≦1, 0≦y≦1) to bury a portion around the projection.
According to the ninth aspect of the invention, there is provided a semiconductor device having a projection on a nitride III-V compound semiconductor base body, comprising:
a buried semiconductor layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) to bury a portion around the projection.
According to the tenth aspect of the invention, there is provided a method for manufacturing a semiconductor device having a projection on a nitride III-V compound semiconductor base body and including a buried semiconductor layer made of A1
x
Ga
1-x
As (0≦×≦1) which buries a portion around the projection, comprising the steps of:
making the projection; and
growing the buried semiconductor layer made of A1
x
Ga
1-x
As (0≦×≦1) to bury the portion around the projection.
According to the eleventh aspect of the invention, there is provided a method for manufacturing a semiconductor device having a projection on a nitride III-V compound semiconductor base body and including a buried semiconductor layer made of (A1
x
Ga
1-x
)
y
In
1-y
P (0≦×≦1, 0≦y≦1) which buries a portion around the projection, comprising the steps of:
making the projection; and
growing the buried semiconductor layer made of (Al1
x
Ga
1-x
)
y
In
1-y
P (0≦×≦1, 0≦y≦1) to bury the portion around the projection.
According to the twelfth aspect of the invention, there is provided a method for manufacturing a semiconductor device having a projection on a nitride III-V compound semiconductor base body and including a buried semiconductor layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) which buries a portion around the projection, comprising the steps of:
making the projection; and
growing the buried semiconductor layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) to bury the portion around the projection.
In the present invention, all of the buried semiconductor layer made of A1
x
Ga
1-x
As (0≦×≦1), buried semiconductor layer made of (A1
x
Ga
1-x
)
y
In
1-y
P (0≦×≦1, 0≦y≦1) and buried semiconductor layer made of Zn
x
Mg
1-x
S
y
Se
1-y
(0≦×≦1, 0≦y≦1) have the [
111
] orientation. For growth of these buried semiconductor layers, metal organic chemical vapor deposition (MOCVD) and molecular epitaxy (MBE) are usable. However, in case of selectively growing a buried semiconductor layer on opposite sides of the ridge-shaped stripe or around the projection, metal organic chemical vapor depos
Asano Takeharu
Ikeda Masao
Tojo Tsuyoshi
Tomiya Shigetaka
Davie James
Sonnenschein Nath & Rosenthal
Sony Corporation
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