JP2963701B2 - Semiconductor laser device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor laser using a semiconductor multilayer reflective film.

[Conventional technology]

Conventional surface-emitting type semiconductor lasers have been published in the 49th Annual Meeting of the Japan Society of Applied Physics (Autumn 1988, 7p-ZC-13, P914) and 36th.
Proceedings of the Japan Society of Applied Physics (Spring 1989, 2P-ZC-8
And 10, P915), the n-side electrode (or p-side electrode) is provided on the semiconductor substrate side, and the p-side electrode (or n-side electrode) is provided on the epitaxial growth layer side. The structure was sandwiched between n electrodes.

[Problems to be solved by the invention]

In the above prior art, the p and n electrodes are provided on both front and back surfaces, and there is a problem in integration of the device, for example, particularly in three-dimensional integration with another optical functional device such as a light receiving device. In addition, in order to improve the heat radiation characteristics of the device, it is necessary to assemble the device by junction down (the epitaxial growth layer side is set to the heat sink side), and the light emission surface must be the substrate side (especially when using a GaAs substrate). It is necessary to use a short cavity structure in order to further reduce the single longitudinal mode operation and the absorption loss in the cavity. Need to be formed. Therefore, a very deep (about 50 to 100 .mu.m) selective etching which reaches the epitaxial growth layer has to be performed, which poses a problem in device fabrication.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface-emitting type semiconductor device that can easily integrate two-dimensionally or three-dimensionally with other elements, as well as two-dimensionally integrate a semiconductor laser, and can easily manufacture the element. It is to provide a laser.

[Means for solving the problem]

In order to achieve the above object, in a surface emitting semiconductor laser having at least a cladding layer, an active layer, and a semiconductor multilayer reflection layer on a semiconductor substrate transparent to laser light,
And n-side electrode on the same plane (epitaxial growth layer side)
And the laser light is emitted from the semiconductor substrate side. At this time, the p and n side electrodes were separated by an isolation groove. Further, the formation of the short resonator structure was achieved by adopting a structure having a semiconductor multilayer reflective film on both the p-side and the n-side.

[Action]

By providing the p-side and n-side electrodes in the same plane on the epitaxial growth layer side and providing a separation groove surrounding the resonator region, the problem of the surface emission type, that is, uniformization of the light emission surface, is not a problem. In addition, electrodes are not obstructed when other elements are stacked and integrated, and the integration becomes easy. Further, by providing two semiconductor multilayer film reflection layers on the p and n sides, a short resonator structure can be easily obtained, and by using a substrate transparent to laser light, selective etching of the light emitting portion is required. And not. Therefore, element fabrication is easy.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

Example 1 As shown in FIG. 1, Al _x Ga _{1_x} which is transparent to laser light
A current path between a p-side region and an n-side region is formed on an As substrate (metal oxide vapor phase epitaxy (MOCDV) method) on an As substrate (x = 0.10 to 0.40 because the laser beam wavelength is 830 nm in the second embodiment). become _{p-Al x Ga 1_x as (} x = 0.1~0.40, carrier concentration 1 × 10 ¹⁸ cm ^-3, thickness 20 [mu] m) were grown 2, further p-AlGa
As the multilayer reflective layer _{3, p-Al x Ga 1_x} As (x = 0.37,0.5~1
× 10 ¹⁸ cm ^-3 , ~ 5 µm) cladding layer 4, multiple quantum well (MQ
W) active layer _{5, n-Al x Ga 1_x} As (x = 0.37,1 × 10 18 cm -3,
6, n-AlGaAs multilayer reflective layer 7, n-GaAs (up to 5 × 10
⁽¹⁸ cm ⁻³ , 1 μm) The contact layers 8 are sequentially laminated. AlGa
The As multilayer reflection layers 3 and 7 are composed of two layers, a low refractive index layer and a high refractive index layer, and are formed by repeating the layers. These higher refractive index difference between the two layers is greater reflectivity of the reflective layer is increased, although the low refractive index layer is optimal AlAs layer, in the present embodiment considering easiness of MOCVD established Al _0.6 Ga
_{A 0.4} As layer (64.4 nm) was used as a low refractive index layer. The high refractive index layer is an Al _0.2 Ga _0.8 As layer (59.4 nm). The p-side reflection layer is composed of 20 pairs of these two layers, and the carrier concentration is 0.5 to
1 × 10 ¹⁸ cm ⁻³ , the reflectance at this time is about 90%. Also,
The n-side reflection layer is composed of 30 pairs of the above two layers, and the carrier density is 1 × 10 ¹⁸ cm ⁻³ . The reflectivity for 98 pairs is 98%. The MQW active layer 5 includes a GaAs well layer (8 nm) and Al _0.2 Ga _0.8
It is composed of an As barrier layer (3 nm), has an active layer thickness of 2 to 5 μm, and has a p-type conductivity (carrier concentration of 0.5 to 1 × 10 ¹⁸ cm ⁻³ ).
The light emitting area was 10 to 20 μmφ.

The above-mentioned wafer is subjected to Zn diffusion 9 as shown in the figure, so that the p-type region and the n-type region are
The isolation is achieved by forming an isolation groove 10 reaching the lGaAs layer 2. Furthermore, the AlGaAs substrate 1
The side is polished and chemically etched to make the wafer layer about 100 μm. Thereafter, a p-electrode 11 and an n-electrode 12 are formed to form an element.

In the surface emitting semiconductor laser device according to the present embodiment,
CW operation with an oscillation wavelength of 830 nm and a threshold current of 30 mA was obtained.

Embodiment 2 Another embodiment of the present invention will be described with reference to FIG. MOCVD
Semiconductor layers 2 to 6 are sequentially grown epitaxially on an AlGaAs substrate 1 by the method in the same manner as in the first embodiment. Thereafter, the n-GaAs contact layer 8 is successively laminated. Next, after performing Zn diffusion as in the first embodiment, an insulating film (about 2000 °) is formed on a part of the n-GaAs contact layer. This insulating film was formed in the center of the light emitting region at 5 to 15 μmφ. Thereafter, polishing and chemical etching are further performed in the same manner as in Example 1, and p and n electrodes are formed to form an element. The resonator of the device according to the present embodiment is constituted by a semiconductor multilayer reflective layer (p-side) and an electrode 12 (n-side). Even in such a device, device characteristics not significantly different from Example 1 were obtained.

In this embodiment, only the AlGaAs type is shown, but the present invention
The present invention is also applicable to InP-based substrates. In the case of an InP substrate, it is also convenient for epitaxial growth that the substrate itself is transparent to laser light. In this embodiment, the case where the light emitting surface is flat is described, but at least a part of the light emitting surface may be formed in a dome shape. In this case, the coupling efficiency of the optical fiber and other devices is increased.

Further, in this embodiment, only the surface-emitting type semiconductor laser is shown alone, but a two-dimensional array of laser elements or a stacked integration with other devices, which is an original object of the present invention, may be performed.

〔The invention's effect〕

In the surface-emitting type semiconductor laser according to the present invention, the p-side electrode and the n-side electrode are provided on the same plane and the separation groove is provided so as to surround the resonator region. While making the difficulties of the mold irrelevant, the electrodes are not obstructed during the stack integration with other devices, and the integration is easy. Further, by using a substrate transparent to laser light and two semiconductor multilayer film reflective layers together, it is not necessary to selectively remove a part of the light emitting surface, and the device can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a surface emitting semiconductor laser according to one embodiment of the present invention, and FIG. 2 is a sectional view of a surface emitting semiconductor laser according to another embodiment of the present invention. 1 ... AlGaAs substrate, 3 ... p-AlGaAs multilayer reflective layer, 5
... MQW active layer, 7 ... n-AlGaAs multilayer reflective layer, 9 ...
... Zn diffusion, 10 ... isolation groove, 11 ... p electrode,
12 ... n electrode, 13 ... insulating film.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichi Ono 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Kunio Aiki 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. (56) References JP-A-1-103896 (JP, A) JP-A-62-1465 (JP, A) JP-A-60-42890 (JP, A) JP-A-61-43491 (JP) , A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (3)

(57) [Claims] 1. A semiconductor laminate having a first semiconductor region of a first conductivity type, a second semiconductor region including a light emitting region, and a third semiconductor region of a second conductivity type above a light-transmitting semiconductor substrate. Wherein the first semiconductor region has a first semiconductor multilayer film formed by alternately stacking semiconductor layers having different refractive indices, and the third semiconductor region is formed at least by the first semiconductor multilayer film. A surface-emitting type resonator region is configured to include the semiconductor laminated body, and the semiconductor laminated body is formed in a region other than a region forming a resonator region with a groove and a resonator region surrounding the resonator region. The groove is a groove extending from the third semiconductor region to the first semiconductor region, and is separated from the third semiconductor region in a region of the semiconductor laminate other than the region forming the resonator region separated by the groove. Semiconductor region and the second semiconductor region are the first conductive region. A first electrode on the side of the third semiconductor region on the side forming the resonator region, and a third electrode in a region other than forming a resonator region surrounding the resonator region of the semiconductor laminate. A semiconductor laser device having a second electrode on a semiconductor region side. 2. A semiconductor laminate having a first semiconductor region of a first conductivity type, a second semiconductor region including a light emitting region, and a third semiconductor region of a second conductivity type above a light-transmitting semiconductor substrate. Wherein the first semiconductor region has a first semiconductor multilayer film in which semiconductor layers having different refractive indexes are alternately stacked, and the third semiconductor region has semiconductor layers having different refractive indexes alternately. A second semiconductor multilayer film formed by laminating the first semiconductor multilayer film to the third semiconductor region to form a surface-emitting resonator region including a semiconductor multilayer body; The laminate is separated into a region that forms a resonator region by a groove and a region other than a region that forms a resonator region surrounding the resonator region, and the groove extends from the third semiconductor region to the first semiconductor region. A groove, constituting the resonator region separated by the groove The third semiconductor region and the second semiconductor region in the region of the outer semiconductor laminate are of the first conductivity type, and the first electrode and the third semiconductor region on the side forming the resonator region are connected to the first electrode. A semiconductor laser device having a second electrode on a third semiconductor region side of a region other than forming a resonator region surrounding the resonator region of the semiconductor laminate. 3. A semiconductor laminate having a first semiconductor region of a first conductivity type, a second semiconductor region including a light emitting region, and a third semiconductor region of a second conductivity type above a light-transmitting semiconductor substrate. Wherein the first semiconductor region has a first semiconductor multilayer film formed by alternately stacking semiconductor layers having different refractive indices, and a region in which the semiconductor stacked body forms a resonator region with a groove. The groove is separated into regions other than constituting a resonator region surrounding the resonator region, and the groove is a groove extending from the third semiconductor region to the first semiconductor region. The third semiconductor region and the second semiconductor region of the region of the semiconductor laminated body other than constituting the surrounding resonator region are the first semiconductor region.
A first electrode on the side of the third semiconductor region on the side forming the resonator region and a third electrode of a region of the semiconductor laminate other than forming a resonator region surrounding the resonator region;
A semiconductor laser device having a second electrode on the side of the semiconductor region, and a surface emission type resonator region formed in a region from the first semiconductor multilayer film to the first electrode. .