Group III nitride semiconductor optical device
AssigneeNEC Corporation
InventorsKazuhisa Fukuda, Chiaki Sasaoka, Akitaka Kimura
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Abstract
The present invention provides a semiconductor laser excellent in the current injection efficiency. In an inner stripe type semiconductor laser according to the present invention, a p type cladding layer 309 has a superlattice structure composed of GaN layers and Al0.1Ga0.9N layers, which are alternately layered on each other. The p type cladding layer 309 has a portion of high dislocation density and a portion of low dislocation density. That is, the dislocation density is relatively low in a region directly above an opening of the current-confining region 308, whereas the dislocation density is relatively high in a region directly above a current-confining region 308.
Claims7
A Group III nitride semiconductor optical device comprising:
- an active layer made of a Group III nitride semiconductor;
- a current-confining layer provided over the active layer;
- an opening for current injection provided as a current injection region in the current-confining layer;
- a cladding layer of a superlattice structure provided on an upper part of the current-confining layer and the opening for current injection;
- a contact layer provided on an upper part of the cladding layer;
- and
- an electrode provided on a surface of the contact layer,
- wherein the dislocation density of the cladding layer in a region directly above the current-confining layer is higher than the dislocation density of the cladding layer in a region directly above the opening for current injection,
- wherein the current-confining layer is made of AlxGayIn1-x-yN (0.4≦×≦1, 0≦y≦0.6, 0 ≦×+y≦1),
- wherein the thickness of the current-confining layer is selected in the range of 50 nm or thicker, but 200 nm or thinner,
- wherein the Group III nitride semiconductor optical device further comprises an insulating layer having an opening that is provided on the surface of the contact layer,
- wherein the electrode is provided so as to be in contact with the contact layer exposed in the opening,
- wherein the opening for current injection of the current injection region is in stripe shape,
- wherein the current-confining layer is constituted by a pair of stripe-shaped current-confining layers provided on both sides of the stripe-shaped opening for current injection, and
- wherein each of ends of the opening provided in the insulating layer is positioned over the current-confining layers.
A Group III nitride semiconductor optical device comprising:
- an active layer made of a Group III nitride semiconductor;
- a current-confining layer provided over the active layer;
- an opening for current injection provided as a current injection region in the current-confining layer;
- a cladding layer of a superlattice structure provided on an upper part of the current-confining layer and the opening for current injection;
- a contact layer provided on an upper part of the cladding layer;
- and
- an electrode provided on a surface of the contact layer,
- wherein the dislocation density of the cladding layer in a region directly above the current-confining layer is higher than the dislocation density of the cladding layer in a region directly above the opening for current injection,
- wherein the current-confining layer is made of AlxGayIn1-x-yN (0.4≦×≦1, 0≦y≦0.6, 0 ≦×+y≦1),
- wherein the thickness of the current-confining layer is selected in the range of 50 nm or thicker, but 200 nm or thinner,
- wherein the current-confining layer is made of a low-temperature grown AlxGayIn1-x-yN (0.4≦×≦1, 0≦y≦0.6, 0 ≦×+y≦1),
- wherein the cladding layer has p type electrical conductivity, and
- wherein an undoped GaN layer is provided on the surface of the current-confining layer.
Dependencies are inferred from the claim text.