Nitride semiconductor device
A nitride semiconductor device used chiefly as an LD and an LED element. In order to improve the output and to decrease Vf, the device is given either a three-layer structure in which a nitride semiconductor layer doped with n-type impurities serving as an n-type contact layer where an n-electrode is formed is sandwiched between undoped nitride semiconductor layers; or a superlattice structure of nitride. The n-type contact layer has a carrier concentration exceeding 3×10 10 cm 3 , and the resistivity can be lowered below 8×10 −3 Ωcm.
1. A nitride semiconductor light emitting device comprising:
a substrate,
a first nitride semiconductor layer being undoped and being a single layer,
a second nitride semiconductor layer having an n-type electrode and being a single layer,
a third nitride semiconductor layer being a super lattice layer of GaN layers, and
a separate and distinct active layer where electrons and holes are combined.
2. The nitride semiconductor light emitting device according to claim 1 ;
wherein said second nitride semiconductor layer is made of GaN or AlGaN and said second nitride semiconductor layer includes Si as an n-type impurity.
3. The nitride semiconductor light emitting device according to claim 1 ;
wherein said first nitride semiconductor layer is made of GaN or AlGaN.
4. The nitride semiconductor light emitting device according to claim 1 ;
wherein said second nitride semiconductor layer has an carrier concentration more than 3×10 18 /cm 3 .
5. The nitride semiconductor light emitting device according to claim 1 ;
wherein said second nitride semiconductor layer has a resistivity less than 8×10 −3 ohm·cm.
6. The nitride semiconductor light emitting device according to claim 1 ;
further comprising a buffer layer between said substrate and said first nitride semiconductor layer.
7. The nitride semiconductor light emitting device according to claim 1 ;
wherein said first nitride semiconductor layer has a thickness within a range of from 0.1 to 20 μm.
8. The nitride semiconductor light emitting device according to claim 1 ;
wherein said second nitride semiconductor layer has a thickness within a range of from 0.1 to 20 μm.
9. The nitride semiconductor light emitting device according to claim 1 ;
wherein said third nitride semiconductor layer being a super lattice layer of undoped GaN layers and Si doped GaN layers.
10. The nitride semiconductor light emitting device according to claim 9 ;
wherein said Si doped GaN layers are doped with Si to 1×10 19 /cm 3 .
11. The nitride semiconductor light emitting device according to claim 9 ;
wherein said undoped GaN layers have a thickness of 75 Å and Si doped GaN layers have a thickness of 25 Å.
12. The nitride semiconductor light emitting device according to claim 9 ;
wherein said third nitride semiconductor layer has a thickness of 600 Å.