JPH0555704A - Plane emission semiconductor laser, its array, plane emission led, its array & plane emission pnpn element - Google Patents

Abstract

PURPOSE:To control polarization direction in a plane emission type semiconductor laser and plane emission type LED utilizing natural ultra-lattice. CONSTITUTION:A GaInP activated layer 3 forming a natural ultralattice is contained on a semiconductor GaAs substrate 1, and a plane light-emitting type semiconductor laser has a resonator in the direction normal to the plane of substrate 1. By this construction, it becomes possible to stably control the polarization direction in [110] direction. Also, in a semiconductor laser array with these elements integrated on the same substrate, it is possible to align the polarization direction of each element in [110] direction. This can be applied not only to semiconductor laser but also to a lightemitting element such as plane light-emitting type LED.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor laser in which polarization direction controllability is good and stabilized, a semiconductor laser array in which the polarization directions of individual elements are aligned, and polarization direction dependence. The present invention relates to a light emitting diode and a light emitting diode array in which polarization directions of individual elements are aligned.

[0002]

2. Description of the Related Art In recent years, surface-emitting type semiconductor lasers for extracting light in a direction perpendicular to a substrate surface have been actively researched and developed as applications to information processing fields such as light sources for optical disks and optical computing applications. Surface-emitting type semiconductor lasers that continuously operate at room temperature are also described in Japanese Journal of Applied Physics (A. Ibaraki et al.
Jpn. J. Appl. Phys. Vol. 28 (19
89) L667).

In a semiconductor laser which normally takes out the optical output from the end face direction, since the mode selectivity of the end face reflection is remarkable due to the waveguide structure, it stably oscillates in the TE mode. Even a surface-emitting type semiconductor laser can oscillate with linearly polarized light by Journal of Quantum Electronics (K. Iga).
et al. IEEE J. Quantum Elec
tron. Vol. QE-21 (1985) p.663)
It is reported that the polarization direction is transmitted in the [110] direction or the [1, -1,0] direction, and the Japanese Journal of Applied Physics (M. Shim).
izu et al. Jpn. J. Appl. Phy
s. Vol. 27 (1989) p. 1774), the surface-emitting type semiconductor laser is isotropic with respect to the beam vertical direction, so that the polarization direction cannot be uniquely defined and is unstable. In some cases. Attempts have also been made to control the polarization direction by depositing Si on one side surface of a dielectric multilayer film, which is a p-side mirror, and by providing a loss (Preliminary lecture at the Joint Symposium on Applied Physics in Spring 1991). Vol. 31a-D-2).

Further, a normal light emitting diode has no polarization direction dependency and emits light with a random electric field vector. Therefore, it is quite difficult to control the polarization direction.

[0005]

In the conventional surface-emitting type semiconductor laser, anisotropy due to roughness of the crystal surface or stress,
It is difficult to control and stabilize the polarization direction because the polarization direction is determined by a combination of non-parallel mirror surfaces, mesa-shaped anisotropy, and vapor-deposited film anisotropy. [11
The method of controlling the polarization direction by providing a loss in either the [0] direction or the [1, -1,0] direction requires complicated steps, and the beam shape may be deformed from the circular shape. ..

Further, in the conventional light emitting diode, the electric field vector of the emitted light is random, and the polarization direction has no dependence on the vertical direction of the emitted light.

Further, in a surface emitting element array in which surface emitting elements whose polarization directions are not controlled are integrated on the same substrate, there is a high possibility that the polarization directions of the individual elements will be different.
It is difficult to provide a surface emitting element array in which the polarization direction is aligned in one direction.

The object of the present invention is to use a crystal having polarization direction dependency in the active layer, so that the polarization direction can be easily controlled, and a complicated manufacturing process such as providing a loss in one direction where the element is present can be realized. A surface-emitting type semiconductor laser and a surface-emitting type light-emitting diode that do not require the introduction of a structure that deforms the beam shape and a polarization in which the surface-emitting type semiconductor laser or the surface-emitting type light-emitting diode is integrated on the same substrate. An object of the present invention is to provide a semiconductor laser array and a light emitting diode array or a surface emitting pnpn element whose directions are aligned.

[0009]

A surface-emitting type semiconductor laser of the present invention is characterized by including an active layer having a natural superlattice formed on a semiconductor substrate and having a resonator in a direction perpendicular to the substrate surface. To do.

The semiconductor laser array of the present invention is characterized in that the above-mentioned surface-emitting type semiconductor lasers are integrated on the same substrate.

Further, the surface emitting light emitting diode of the present invention is characterized in that it has an active layer having a natural superlattice formed on a semiconductor substrate and has a structure for extracting light from the front surface or the back surface of the substrate.

Further, the light emitting diode array of the present invention is characterized in that the above-mentioned surface emitting type light emitting diodes are integrated on the same substrate.

Further, the surface emitting pnpn element is characterized by having a natural superlattice in the active layer or an array thereof.

[0014]

In the epitaxial growth layer of GaInP or AlGaInP, [-1, 1, 1] or [1, -1,
It has been reported that a natural superlattice having a periodic structure with an ordered 1] direction is formed (see, for example, Applied Physics Letters (Gomyo et a.
l. Appl. Phys. Lett. Vol. 50 (1
987) p. 673)). Further, in a semiconductor in which a natural superlattice is formed, the electric field vector of light emission between the lowest levels is (-1, 1, 1) or (1,-
1,1) is biased in the plane of Physical Review Letters (A. Mascarenhas et al.
Phys. Rev. Lett. Vol. 63 (198
9) 2108).

The surface-emitting type semiconductor laser of the present invention has an active layer in which a natural superlattice is formed, and the light output is taken out in the direction perpendicular to the substrate surface.
When the substrate of 1) plane is used, the electric field component of the spontaneous emission light below the oscillation threshold is [11,0] compared to [11,0]
0] direction becomes large. Since the semiconductor laser oscillates in the polarized light in the direction of large gain, the surface emitting semiconductor laser of the present invention emits in the polarized light in the [110] direction. Further, in the surface-emitting light emitting diode of the present invention, the luminous efficiency of the light polarized in the [110] direction becomes high.

Further, in the epitaxial growth layer formed on the semiconductor substrate in which the substrate crystal plane orientation is tilted from the (001) plane in the [-1,1,0] or [1, -1,0] direction, the natural superlattice order is formed. The natural superlattice is formed most strongly on a semiconductor substrate tilted from 4 ° to 6 °. This (00
1) Polarization selectivity is further enhanced by using a substrate that is tilted from the plane, and in surface-emitting type semiconductor lasers, light emission having an electric field vector in the [110] direction is efficiently given a gain, so that oscillation occurs. It also reduces the threshold current. Further, in the surface emitting type light emitting diode and the surface emitting type pnpn element, the polarization direction dependency in the [110] direction is further increased.

Further, in the surface emitting element array in which the surface emitting type semiconductor laser, the surface emitting type light emitting diode or the pnpn element of the present invention are integrated on the same substrate, the polarization direction of each surface emitting type element is [110]. Can be aligned in any direction.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the surface emitting semiconductor laser of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a surface-emitting type semiconductor laser of the present invention, and FIG. 2 is a view for explaining the manufacturing process thereof.

First, as shown in FIG. 2A, n-type Ga
On an As (001) substrate 1, an n-type (Al
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P cladding layer 2,
2.0μm undoped Ga _{0 thick. 5} In _{0. 5} P active layer 3,1.0μm thickness of p-type _{(Al 0. 7 Ga 0.} 3)
_{0. 5} In _{0. 5} P cladding layer 4, 20 pairs of p-type (Al
_{0. 1 Ga 0. 9) 0} . 5 In 0. 5 P / (Al 0. 7
_{Ga 0. 3) 0. 5} In 0. 5 P DBR multi-layer film 5,
0.1μm thick p-type Ga _{0. 5} In _{0. 5} and the P hetero buffer layer 6,0.5Myuemu p-type GaAs cap layer 7 having a thickness laminated grow. p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 I
_{n 0. 5 P / (Al} 0. 7 Ga 0. 3) 0. 5 In
_0.5 The thickness of the P DBR multi-layer film 5 is λ with respect to the oscillation wavelength
/ 2 cycles. Crystal growth is reduced pressure MOVPE
The method was used. The growth conditions were a temperature of 660 ° C., a pressure of 70 Torr, and a group V source supply amount / group III source supply amount ratio (V / III ratio) of 150 so that a natural superlattice was formed. As a raw material, trimethyl aluminum (TM
A), triethylgallium (TEG), trimethylindium (TMI), arsine (AsH ₃ ), phosphine (PH ₃ ), and disilane (Si ₂ H) as an n-type dopant.
₆ ), dimethyl zinc (DMZ) as p-type dopant
Was used.

After forming a SiO ₂ mask 12 having a diameter of 7 μm on this wafer by the lithography method, FIG.
As shown in, p-type _{(Al 0 .7 Ga 0. 3} ) 0. 5 I
n _0.5 P so that the cladding layer 4 remains about 0.3 μm,
P-type GaAs cap layer 7 by wet etching,
p-type _{Ga 0. 5 In 0. 5} P hetero buffer layer 6, p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 In 0. 5 P / (Al
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P DBR multi-layer film 5, p-type _{(Al 0. 7 Ga 0 .3} ) 0. 5 In 0. 5 P
The clad layer 4 was removed.

Next, as shown in FIG. 2 (c), SiO
An n-type GaAs block layer 8 having a thickness of 3 μm was selectively grown by the low pressure MOVPE method using ₂ as a mask. The growth conditions are a temperature of 650 ° C., a pressure of 70 Torr, and a V / III ratio of 4
It was set to 5. As a raw material, trimethylgallium (TM
G), arsine (AsH ₃ ) and disilane (Si ₂ H ₆ ) as an n-type dopant were used. After growing the n-type GaAs block layer 8, the SiO ₂ mask 12 is removed.

Next, the n-electrode 10 is formed, and as shown in FIG.
As shown in FIG. 3, the resist 13 applied on the n-electrode is patterned into a circle having a diameter of 200 μm by a photolithography method so that the circular mesa on the p-side is located at the center, and then the resist 13 is used as a mask to form the n-electrode. 10 and n-type GaAs substrate 1 were removed by wet etching to form a window for emitting light. After removing the resist 13, the p-electrode 11
Was vapor-deposited.

[0023] n-type removal of the n-type GaAs substrate as shown in FIG. _{2 (e) (Al 0.} 7 Ga 0. 3) 0. 5 In
_A dielectric multilayer film reflecting mirror 9 was formed on the 0.5 P clad layer 2. This dielectric multilayer mirror 9 and p-type (Al _0.1 G
_{a 0. 9) 0. 5} In 0. 5 P / (Al 0. 7 Ga
_0.3 ) _0.5 In _0.5 P The multilayer film 5 forms a resonator. Finally, each element is separated by cleavage, and p
The electrode side was fused and mounted on a heat sink.

The polarization direction during oscillation of the surface-emitting type semiconductor laser of this example thus obtained is [110].

The substrate plane orientation is from the (001) plane to [-1,
On the n-type GaAs substrate tilted by 6 ° in the [1,0] direction, as shown in FIG.
A surface-emitting type semiconductor laser having the same structure as the above was formed. This surface-emitting type semiconductor laser was stably polarized in the [110] direction, and the oscillation threshold current was reduced by 15% as compared with the surface-emitting type semiconductor laser using the (001) substrate.

FIG. 3 shows the structure of a semiconductor laser array in which 9 surface-emitting type semiconductor lasers are integrated on the same substrate at intervals of 400 μm. The structure of each surface emitting semiconductor laser is shown in FIG.
Is the same as. The polarization directions of the individual laser beams of this semiconductor laser array are aligned in the [110] direction.

Next, one embodiment of the surface emitting type light emitting diode of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view of a surface emitting light emitting diode according to the present invention, and FIG. 5 is a view showing a manufacturing process thereof.

First, as shown in FIG. 5A, n-type Ga
On an As (001) substrate 1, an n-type (Al
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P cladding layer 2,
2.0μm undoped Ga _{0 thick. 5} In _{0. 5} P active layer 3,5.0μm thickness of p-type _{(Al 0. 7 Ga 0.} 3)
_{0. 5} In _{0. 5} P cladding layer 4,0.1Myuemu p-type Ga _{0 thick. 5} In _{0. 5} P hetero buffer layer 6,0.5μ
An m-thick p-type GaAs cap layer 7 was grown. The crystal growth method, growth conditions, and raw materials are the same as those of the above-described surface emitting semiconductor laser. As shown in FIG. 5B, Si having a hole with a diameter of 30 μm is formed on this wafer by a lithography method.
The O ₂ insulating film 12 was formed.

Next, the n-electrode 10 is formed, and as shown in FIG.
As shown in FIG. 3, the resist 13 applied on the n-electrode is formed on the p-side SiO ₂ insulating film 12 by photolithography.
After patterning in a circle having a diameter of 200 μm so that the circular hole is located at the center, the n-electrode 10 and the n-type GaAs substrate 1 are removed by wet etching using the resist 13 as a mask to form a window for light emission. As shown in FIG. 2D, the p-electrode 11 was vapor-deposited after removing the resist. Finally, each element was separated by cleavage, and the p-electrode side was fused and mounted on the heat sink.

The surface emitting light emitting diode of the present invention thus obtained has a high polarization direction dependency and 65% or more of the emitted light is polarized in the [110] direction.

The substrate plane orientation is from the (001) plane to [-1,
On the n-type GaAs substrate tilted by 6 ° in the [1,0] direction, as shown in FIG.
A surface-emitting type light emitting diode having the same structure as described above was formed. Compared with the surface emitting light emitting diode using the (001) substrate, this surface emitting light emitting diode has higher polarization direction dependency and 75% or more of the emitted light is polarized in the [110] direction.

FIG. 6 shows the structure of a light emitting diode array in which nine surface emitting light emitting diodes are integrated at 400 μm intervals on the same substrate. The structure of each surface emitting light emitting diode is similar to that shown in FIG. The polarization directions of the individual emitted lights of this light emitting diode array are aligned in the [110] direction.

As an embodiment of the surface emitting pnpn element of the modified invention, n- (Al _x Ga) is formed on an n-type GaAs substrate.
_1-x ) _0.5 In _0.5 P (0 <x <1), P- (A
_{l Y Ga 1 -.. Y} ) 0 5 In 0 5 P (0 <Y <x <
1), an undoped _{Ga 0. 5 In 0. 5} P active layer, n-
_{.. (Al Y Ga 1 -} Y) 0 5 In 0 5 P, p- (Al
_{x Ga 1 -.. x)} 0 5 In 0 5 P, to form a semiconductor layer made of p-GaAs, to form an electrode in the same manner as described above for the surface-emitting light-emitting diodes, it mounted. Even with this pnpn element, light emission highly dependent on the polarization direction was obtained. This element can be applied as a switching element or an optical functional element. When the array is used, a pnpn element array with uniform polarization directions can be uniformly obtained.

[0034]

The surface-emitting type semiconductor laser of the present invention can be manufactured in a small number of steps because it can stably control the polarization direction and does not require a complicated manufacturing step such as providing a loss in one direction. Therefore, a highly reliable polarization plane control type surface emitting semiconductor laser can be obtained.

Further, the surface-emitting type light emitting diode of the present invention has polarization direction dependency, and its direction can be controlled.

Further, in the semiconductor laser array and the light emitting diode array in which these elements are integrated on the same substrate, the polarization directions of all the integrated elements can be aligned in one direction.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a surface emitting semiconductor laser of the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the surface-emitting type semiconductor laser of the present invention.

FIG. 3 is a structural diagram of an embodiment of a semiconductor laser array of the present invention.

FIG. 4 is a cross-sectional view of an embodiment of the surface emitting light emitting diode of the present invention.

FIG. 5 is a diagram for explaining a manufacturing process of the surface emitting light emitting diode of the present invention.

FIG. 6 is a structural diagram of a light emitting diode array according to an embodiment of the present invention.

[Explanation of symbols]

1 n-type GaAs substrate 2 n-type _{(Al 0. 7 Ga 0.} 3) 0. 5 In 0. 5 P
Cladding layer 3 undoped _{Ga 0. 5 In 0. 5} P active layer 4 p-type _{(Al 0. 7 Ga 0.} 3) 0. 5 In 0. 5 P
Cladding layer 5 p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 In 0. 5 P
_{/ (Al 0. 7 Ga 0} . 3) 0. 5 In 0. 5 P DBR multi-layer film 6 p-type _{Ga 0. 5 In 0. 5} P hetero buffer layer 7 p-type GaAs cap layer 8 n-type GaAs block layer 9 Dielectric multilayer film mirror 10 n electrode 11 p electrode 12 SiO ₂ insulating film 13 resist

Claims (7)

[Claims] 1. A surface-emitting type semiconductor laser having a semiconductor layer including an active layer on which a natural superlattice is formed on a semiconductor substrate and having a resonator in a direction perpendicular to the substrate surface. 2. The semiconductor substrate plane orientation is formed on a semiconductor substrate tilted from the (001) plane in the [-1,1,0] or [1, -1,0] direction. The surface-emitting type semiconductor laser described. 3. A surface emitting semiconductor laser array comprising the surface emitting semiconductor laser according to claim 1 or 2 integrated on the same substrate. 4. A surface-emitting light-emitting diode having a semiconductor layer including an active layer having a natural superlattice formed on a semiconductor substrate, and having a structure for extracting light from the front surface or the back surface of the substrate. 5. The surface-emitting light-emitting device according to claim 4, wherein the surface orientation of the semiconductor substrate is formed on a semiconductor substrate tilted in the [-1,1,0] or [1, -1,0] direction from the (001) plane. diode. 6. A surface emitting type light emitting diode array comprising the surface emitting type light emitting diodes according to claim 4 or 5 integrated on the same substrate. 7. A surface-emitting pnpn device comprising a semiconductor substrate, an active layer having a natural superlattice formed thereon, and a semiconductor having a pnpn structure, and having a structure for extracting light from a front surface or a back surface of the substrate.