JP2952299B2 - Surface emitting laser device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface emitting laser device having a buried structure using a semiconductor multilayer film for a substrate-side reflecting mirror.

[Conventional technology]

FIG. 2 is a cross-sectional structural view of a conventional surface emitting laser device, in which an n-type GaAs buffer layer 22 and a reflective layer are formed on the surface of an n-type GaAs substrate 21 by OMVPE (organic metal vapor phase epitaxy). A semiconductor multilayer film 23 in which a Ga _0.9 Al _0.1 As layer and an AlAs layer constituting a mirror are alternately stacked 25 times, an n-type cladding layer 24
Are sequentially laminated, and a buried layer composed of a p-type active layer (GaAs) 25 and a p-type cladding layer 27 is laminated and formed in this order at the center of the surface of the cladding layer 24 by the same OMVPE method. is there.

In addition, a p-type first block layer 28 and an n-type second block layer 29 are formed around these to bury the active layer 25 and the clad layer 27, and the second block layer 29 and the A planarization layer 30 is formed over the cladding layer 27, and a p-type Ga _0.94 Al _0.06 As contact layer is formed at the center of the planarization layer 30.
A multilayer film (DB) is provided at a position facing the active layer
R) 32, and an electrode 34 is formed therearound with an insulating layer 33 interposed therebetween. Reference numeral 35 denotes an electrode provided on the lower surface side of the substrate 21.

In such a conventional surface emitting laser device, a voltage is applied to both electrodes 34 and 35, light is emitted from the active layer 25, and light is reflected by the multilayer films 23 and 32 on both sides to resonate. After that, the laser beam is emitted in the arrow direction.

[Problems to be solved by the invention]

In general, the active layer 25 is required to have a small thickness in order to reduce the threshold current density. On the other hand, the first block 28 has a thickness less than a certain value in order to maintain the current blocking function. Therefore, when the thickness of the active layer is reduced, the reverse bias junction between the first and second block layers 28 and 29 becomes smaller than the forward bias junction surface 38 between the cladding layer 24 and the active layer 25. The surface 39 is located above, the same p-type first block layer 28 exists around the p-type active layer 25 as the buried layer, and the current injected from the p-type contact layer 31 A part of the current flows into the p-type first block layer 28 and does not concentrate on the p-type active layer 25, resulting in a reactive current that does not contribute to light emission, which causes a problem that light emission efficiency is reduced.

For this reason, there is a limit to the reduction of the film thickness of the active layer 25, and the apparent threshold current density must be increased, and the differential quantum efficiency is reduced. There was a drawback that it became more noticeable as it became.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a surface emitting laser device capable of reducing reactive current and improving luminous efficiency.

[Means for solving the problem]

In the surface emitting laser device according to the present invention, a buried portion including an active layer is formed by forming a first conductive type first block layer and a second conductive type second block layer formed around the buried portion in this order. In a surface emitting laser device embedded by a layer, a substrate, a first semiconductor multilayer film of a second conductivity type formed on the substrate, and a part of the surface of the first semiconductor multilayer film, A second conductivity type intermediate layer having an AlAs composition ratio greater than the AlAs composition ratio of the active layer, and a film thickness of an integral multiple of λ / 2n (λ: emission wavelength, n: refractive index); A buried portion formed by sequentially stacking a second semiconductor multilayer film of a second conductivity type, a first cladding layer of a second conductivity type, the active layer and a second cladding layer of the first conductivity type, and the first semiconductor multilayer film And forming the intermediate layer, the second semiconductor multilayer film, and the first It said first blocking layer to embed the de layer, said second blocking layer to fill the active layer and the second cladding layer and having a blocking layer formed by laminating.

[Action]

According to the present invention, an intervening layer, a second semiconductor multilayer film, and a first cladding layer, which are buried layers, are stacked on the first semiconductor multilayer film and buried with a first block layer. An active layer and a second clad layer are superposed on the layer, and these are buried in a second block layer so that the position of the active layer is kept away from the substrate side, and a reverse bias junction surface between the first and second block layers is formed in the active layer. Can be located near the substrate side interface of
The reactive current to the first and second block layers can be suppressed, and the light loss in the optical path can be suppressed.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments.

FIG. 1 is a sectional view showing the structure of a surface emitting laser device according to the present invention. In FIG. 1, reference numeral 1 denotes a GaAs substrate having an n-type conductivity. An n-type conductivity type having a total thickness of about 2.1 μm by alternately stacking 15 pairs of Ga _0.9 Al _0.1 As layers and AlAs layers on the substrate 1 by OMVPE (organic metal vapor phase epitaxy) is used. The first semiconductor multilayer film 2 is formed by lamination.

The thickness of the first semiconductor multilayer film 2 is made of n-type Ga _0.94 Al _0.06 As by the OMVPE method in the center of the surface.
A second n-type semiconductor multilayer film 4 having a thickness of about 1.4 μm and an n-type Ga _0.65 Al _0.35 layer in which an intervening layer 3 having a thickness of 0.5 μm, and subsequently a Ga _0.9 Al _0.1 As layer and an AlAs layer are alternately laminated ten times. As 0.5 thickness
μm cladding layer 5, p-type GaAs active layer 6 having a thickness of 2 μm, p-type Ga _0.65 Al _0.35 As 0.5 μm thick
Clad layer 7, p-type Ga _0.94 Al _0.06 As
The cap layer 8 of 5 μm is laminated in this order to form a buried layer.

The AlAs composition ratio of the intervening layer 3 is larger than the AlAs composition ratio of the active layer 6, and the thickness is an integral multiple of λ / 2n (λ: oscillation wavelength, n: refractive index of the intervening layer 3) (in the embodiment, 4 times). Around the buried layer, a p-type Ga is embedded so as to bury the intervening layer 3, the second semiconductor multilayer film 4, and the cladding layer 5.
First block layer 9 of _0.45 Al _0.55 As and active layer
6, n-type Ga is buried in the cladding layer 7 and the cap layer 8.
The second block layer 10 made of _0.65 Al _0.35 As and p-type Ga
The As layers 11 are laminated in this order.

Then, over the cap layer 8 and the p-type GaAs layer 11, p
A flattening layer 12 made of Ga _0.94 Al _0.06 As is stacked on top of the Si to form a light-emitting side reflector at the center of the flattening layer 12.
Dielectric multilayer film composed of O ₂ layers and TiO ₂ layers alternately laminated four times
A contact layer 14 made of p-type GaAs, an electrode 15 formed by laminating an Au layer and a Cr layer are formed on the periphery. Reference numeral 16 denotes an electrode formed by laminating an Au layer and a Sn layer formed on the lower surface side of the substrate 1.

Next, an example of a manufacturing process of the device of the present invention as described above will be described. The first semiconductor multilayer film 2, the intermediate layer 3, the second semiconductor multilayer film 4,
After laminating the clad layer 5, the active layer 6, the clad layer 7, and the cap layer 8 in this order, a mask made of Ga _0.55 Al _0.45 As is located at the center of the cap layer 8 where the buried layer is to be formed. The layer is formed to a thickness of 0.25 μm.

Further, after forming a resist layer on the mask layer, first, using the resist layer as a mask, etching is performed by using a sulfuric acid-based etchant until the surface of the first semiconductor multilayer film 2 is exposed, so that a mesa portion which is a buried layer is formed. Form. After removing the resist mask, the intermediate layer 3, the second semiconductor multilayer film 4, and the cladding layer 5 are buried by a selective LPE (liquid phase epitaxial) burying growth method using a mask layer made of Ga _0.55 Al _0.45 As as a mask. The first block layer 9 is subsequently added to the active layer 6,
After forming the second block layer 10 to bury the cladding layer 7 and the cap layer 8, the p-type GaAs layer 11 is grown.

Next, after the mask layer on the cap layer 8 is removed by etching using a sulfuric acid-based etchant, the planarizing layer 12 and the contact layer 14 are formed in this order by the second LPE growth method.

Finally, after the contact layer 14 located above the mesa portion is removed by etching, an SiO ₂ layer and a TiO ₂ layer are alternately formed here.
The dielectric multi-layered film 13 is formed by stacking repeatedly.

Thus, in the device of the present invention, by providing the intervening layer 3, the forward-biased bonding surface 18 formed between the active layer 6 and the clad layer 5 is connected to the first and second blocks. The relative height position with respect to the reverse bias junction surface 19 formed between the layers 9 and 10, in other words, the relative height position of the active layer 6 with respect to the first block layer 9 can be appropriately set and the same. Avoiding contact between the conductive active layer 6 and the first block layer 9,
In addition, the thickness of the first block layer 9 can be reduced to the necessary minimum thickness of about 1 μm, and the thickness of the active layer 6 itself can be set to be small. The increase in resistance can be suppressed, and more effective as the diameter of the buried layer is reduced to reduce the threshold current.

In the above-described embodiment, the case where the intervening layer 3 is interposed between the fifteen pairs of the first semiconductor multilayer films 2 and the ten pairs of the second semiconductor multilayer films 4 is shown. However, the present invention is not limited to this. The setting of the second semiconductor multilayer film 4 may be appropriately changed within the range of 5 to 20 pairs.

〔effect〕

As described above, in the present invention, the position of the substrate-side interface of the active layer and the position of the reverse bias junction surface functioning as an electric block can be matched, the reactive current can be reduced, and excess heat generation can be suppressed. The present invention has excellent effects such as an improvement in temperature characteristics, a reduction in threshold current density, and an improvement in luminous efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of the apparatus of the present invention, and FIG. 2 is a sectional structural view of a conventional apparatus. DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... 1st semiconductor multilayer film, 3 ... intervening layer, 4 ... 2nd semiconductor multilayer film, 5 ... clad layer, 6
... active layer, 7 ... clad layer, 8 ... cap, layer 9,
10: first and second block layers, 18: forward bias junction surface, 19: reverse bias junction surface

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotaro Furusawa 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Tohru Ishikawa 2-18-18 Keihanhondori, Moriguchi-shi, Osaka (56) References JP-A-1-248587 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (1)

(57) [Claims] An embedded portion including an active layer is formed around a first block layer of a first conductivity type and a second block layer of a second conductivity type formed therearound.
A surface emitting laser device in which a block layer is buried by a block layer formed in order, a substrate, a first semiconductor multilayer film of a second conductivity type formed on the substrate, and the first semiconductor multilayer film. A second conductive layer formed on a portion of the surface of the active layer, having an AlAs composition ratio greater than the AlAs composition ratio of the active layer, and having a film thickness that is an integral multiple of λ / 2n (λ: emission wavelength, n: refractive index). Embedded portion formed by sequentially stacking an intervening layer of a second conductivity type, a second semiconductor multilayer film of a second conductivity type, a first clad layer of a second conductivity type, the active layer, and a second clad layer of the first conductivity type. A first block layer formed around the buried portion on the first semiconductor multilayer film and burying the intervening layer, the second semiconductor multilayer film, and the first clad layer, and the active layer And a block formed by laminating the second block layer so as to bury the second clad layer. And a surface emitting laser device comprising: