Semiconductor light-emitting device, and a method of manufacture of a semiconductor device
A method of manufacturing a nitride semiconductor device comprises the steps of: growing an In x Ga 1-x N (0≦x≦1) layer, and growing an aluminium-containing nitride semiconductor layer over the In x Ga 1-x N layer at a growth temperature of at least 500° C. so as to form an electron gas region at an interface between the In x Ga 1-x N layer and the nitride semiconductor layer. The nitride semiconductor layer is then annealed at a temperature of at least 800° C. The method of the invention can provide an electron gas having a sheet carrier density of 6×10 13 cm −2 or greater. An electron gas with such a high sheet carrier concentration can be obtained with an aluminium-containing nitride semiconductor layer having a relatively low aluminium concentration, such as an aluminium mole fraction of 0.3 or below, and without the need to dope the aluminium-containing nitride semiconductor layer or the In x Ga 1-x N layer.
1. A semiconductor light-emitting device fabricated in a nitride material system and comprising: an active region for light emission and an electron gas region disposed on the n-type side of the active region; wherein the electron gas region contains, in use, an electron gas having a sheet electron density of at least 6×10 13 cm −2 .
2. A device as claimed in claim 1 wherein the device comprises a first layer disposed on the n-type side of the active region and a second layer forming part of the active region of the device and disposed adjacent to the first layer, the second layer having a different composition from the first layer whereby the electron gas region is defined at the interface between the first layer and the second layer.
3. A device as claimed in claim 2 wherein the first layer is disposed immediately adjacent to the second layer.
4. A device as claimed in claim 2 , wherein the first layer is a GaN layer.
5. A device as claimed in claim 2 , wherein the first layer is an InGaN layer.
6. A device as claimed in claim 2 , wherein the second layer is an aluminium-containing nitride layer.
7. A device as claimed in claim 6 wherein the second layer is an AlGaN layer.
8. A device as claimed in claim 2 , wherein the first layer is not intentionally doped.
9. A device as claimed in claim 2 , wherein the first layer is doped n-type.
10. A device as claimed in claim 2 , wherein the second layer is not intentionally doped.
11. A device as claimed in claim 2 , wherein the second layer is doped n-type.
12. A device as claimed in claim 1 wherein the electron gas region contains, in use, a 2-dimensional electron gas.
13. A device as claimed in claim 1 wherein the electron gas region contains, in use, a 3-dimensional electron gas.
14. A device as claimed in claim 1 wherein the device is a light-emitting diode.
15. A device as claimed in claim 1 wherein the device is a semiconductor laser device.
16. A method as claimed in claim 1 , wherein the electron gas region is disposed outside the active region.