Semiconductor light-emitting device and process for production thereof
One aspect of the present invention provides a semiconductor light-emitting device improved in luminance, and also provides a process for production thereof. The process comprises a procedure of forming a relief structure on the light-extraction surface of the device by use of a self-assembled film. In that procedure, the light-extraction surface is partly covered with a protective film so as to protect an area for an electrode to be formed therein. The electrode is then finally formed there after the procedure. The process thus reduces the area incapable, due to thickness of the electrode, of being provided with the relief structure. Between the electrode and the light-extraction surface, a contact layer is formed so as to establish ohmic contact between them.
1. A process for production of a semiconductor light-emitting device having a semiconductor layer the surface of which a relief structure and an electrode are formed on and light is extracted from, comprising:
stacking an active layer and said semiconductor layer on a substrate,
providing said semiconductor layer with such a contact layer as brings said electrode and the surface of said semiconductor layer into ohmic contact with each other,
forming an oxide film on the surface of said semi-conductor layer in an area where said electrode is to be formed,
forming a protective film on said semiconductor layer in the whole surface area including the area where said oxide film is formed,
forming a self-assembled film on said protective film,
fabricating said protective film by dry etching through said self-assembled film as a mask, to form a protective film mask,
fabricating said semiconductor layer by dry etching through said protective film mask, to form said relief structure, and
removing said oxide film in the area where said electrode is to be formed, followed by depositing there an electro-conductive material on said contact layer to form said electrode.
2. The process according to claim 1 , wherein said protective film is made of at least one material selected from the group consisting of silicon dioxide, silicon nitride, silicon oxide nitride, and titanium oxide.
3. The process according to claim 1 , wherein said protective film has a thickness of 300 nm or less.
4. The process according to claim 1 , wherein said oxide film is made of silicon dioxide.
5. The process according to claim 1 , wherein said semi-conductor layer is a current spreading layer.
6. The process according to claim 1 , wherein the surface of said semiconductor layer contains at least three elements.
7. The process according to claim 1 , wherein the surface of said semiconductor layer contains at least one material selected from the group consisting of InGaAlP, AlGaAs and AlGaN.
8. The process according to claim 1 , wherein said contact layer contains GaAs or GaN.
9. The process according to claim 1 , wherein said self-assembled film comprises a block copolymer including two or more segments.
10. The process according to claim 1 , wherein said self-assembled film is formed by spin-coating.
11. The process according to claim 1 , wherein said electro-conductive material is gold, gold-zinc alloy, gold-germanium alloy or gold-nickel alloy.
12. A process for production of a semiconductor light-emitting device having a semiconductor layer the surface of which a relief structure and an electrode are formed on and light is extracted from, comprising:
stacking an active layer and said semiconductor layer on a substrate,
forming an oxide film on the surface of said semi-conductor layer in an area where said electrode is to be formed,
forming a protective film on said semiconductor layer in the whole surface area including the area where said oxide film is formed,
forming a self-assembled film on said protective film,
fabricating said protective film by dry etching through said self-assembled film as a mask, to form a protective film mask,
fabricating said semiconductor layer by dry etching through said protective film mask, to form said relief structure,
removing said oxide film in the area where said electrode is to be formed, followed by depositing an electro-conductive material there on said semiconductor layer to form said electrode, and
establishing ohmic contact between said electrode and the surface of said semiconductor layer.
13. A semiconductor light-emitting device produced by the process according to claim 1 , wherein said relief structure is formed in an area of 10 μm or less from the electrode.
14. A semiconductor light-emitting device produced by the process according to claim 12 .