Light-emitting semiconductor device using gallium nitride compound semiconductor
A barrier layer made of Al x Ga 1−x N (0<x≦0.18) is formed in a light-emitting semiconductor device using gallium nitride compound having a multi quantum-well (MQW) structure. By controlling a composition ratio x of aluminum (Al) or thickness of the barrier layer, luminous intensity of the device is improved. An n-cladding layer made of Al x Ga 1−x N (0<x≦0.06) is formed in a light-emitting semiconductor device using gallium nitride compound. By controlling a composition ratio x of aluminum or thickness of the n-cladding layer, luminous intensity of the device is improved. A p-type layer and an n-type layer are formed in a light-emitting semiconductor device using gallium nitride compound having a double-hetero junction structure. By controlling a ratio of a hole concentration of the p-type layer and an electron concentration of the n-type layer approximates to 1, luminous intensity of the device is improved.
1. A light-emitting device using a gallium nitride compound semiconductor comprising:
an emission layer with a multi quantum-well (MQW) structure, in which a barrier layer and a well layer are formed alternatively;
an n-layer comprising Al x Ga 1−x N, wherein 0.03≦×≦0.06, having a thickness from 150 nm to 250 nm;
a substrate; and
a buffer layer formed on said substrate,
wherein said barrier layer is made of Al x Ga 1−x N.
2. A light-emitting device using a gallium nitride compound semiconductor according to claim 1 , wherein said buffer layer is formed at a temperature of 1000° C. to 1180° C.
3. A light-emitting device using a gallium nitride compound semiconductor according to claim 1 , wherein said buffer layer has a thickness of 0.01 μm to 3.2 μm.
4. A light-emitting device using a gallium nitride compound semiconductor according to claim 1 , wherein said buffer layer is formed by physical vapor deposition including any of sputtering, ion plating, and laser-ablation.
5. A light-emitting device using a gallium nitride compound semiconductor according to claim 4 , wherein said buffer layer has a thickness of 100 Å to 3000 Å.
6. A light-emitting device using a gallium nitride compound semiconductor according to claim 4 , wherein said buffer layer is formed at a temperature of 200° C. to 600° C.
7. A light-emitting device using a gallium nitride compound semiconductor according to claim 4 , wherein said buffer layer is treated by heat treatment at a temperature of 1000° C. to 1250° C.
8. A light-emitting device using a gallium nitride compound semiconductor according to claim 7 , wherein said heat treatment is carried out in an atmosphere of H 2 and NH 3 gases.
9. A light-emitting device using a gallium nitride compound semiconductor according to claim 1 , wherein said well layer comprises In y Ga 1−y N, wherein 0<y<0.1.