Light emitting device using GaN LED chip

1. A light emitting device comprising:

a GaN-based LED chip, said GaN-based LED chip being flip-chip mounted, and comprising a light-transmissive substrate, a GaN-based semiconductor layer disposed on said light-transmissive substrate, and a negative electrode partially disposed on a backside of said light-transmissive substrate, said light-transmissive substrate having electrical conductivity, and said GaN-based semiconductor layer having a laminate structure comprising an n-type layer, a light emitting layer and a p-type layer in this order from a light-transmissive substrate side,

wherein a positive electrode is formed on the p-type layer, said electrode comprising

a light-transmissive electrode including an oxide semiconductor, and

a positive contact electrode electrically connected to said light-transmissive electrode, and

wherein an area of said positive contact electrode is less than ½ of an area of an upper surface of said p-type layer.

2. The light emitting device of claim 1 , wherein said area of said positive contact electrode is less than ⅓ of said area of said upper surface of said p-type layer.

3. The light emitting device of claim 2 , wherein said area of said positive contact electrode is less than ¼ of said area of said upper surface of said p-type layer.

4. The light emitting device of claim 1 , wherein said GaN-based LED chip is encapsulated with a resin.

5. The light emitting device of claim 1 , wherein said light-transmissive electrode has a planarized surface, said planarized surface being planarized by polishing.

6. The light emitting device of claim 1 , wherein said light-transmissive substrate is an n-type conductive semiconductor single crystal substrate.

7. The light emitting device of claim 6 , wherein said light-transmissive substrate is a silicon carbide, zinc oxide, GaN or AlGaN.

8. The light emitting device of claim 1 , wherein said positive contact electrode is a single layer film or multi-layer film having, at least on a side in contact with said light-transmissive electrode, a layer made of Al, Ag, Rh or Pt or an alloy made from at least one of Al, Ag, Rh and Pt.

9. The light emitting device of claim 1 , further comprising an insulating protective film applied so as to coat a surface of said light-transmissive electrode, said film having a surface with higher planarity than a planarity of said surface of said light-transmissive electrode.

10. The light emitting device of claim 1 , wherein said positive contact electrode includes

a part bonded to a base, and

a current diffusion part extending from said part on said light-transmissive electrode.

11. The light emitting device of claim 1 , wherein the negative electrode includes

a light-transmissive ohmic electrode, and

a metallic contact electrode partially formed on a surface of said light-transmissive ohmic electrode.

12. The light emitting device of claim 1 , wherein said negative electrode is a metal electrode, which acts as both an ohmic electrode and a contact electrode.

13. A light emitting device comprising:

a GaN-based LED chip, said GaN-based LED chip being flip-chip mounted, and comprising a light-transmissive substrate, a GaN-based semiconductor layer disposed on said light-transmissive substrate, and a negative electrode disposed on a backside of said light-transmissive substrate, said light-transmissive substrate having electrical conductivity, and said GaN-based semiconductor layer having a laminate structure comprising an n-type layer, a light emitting layer and a p-type layer in this order from a light-transmissive substrate side,

wherein a positive electrode is formed on the p-type layer, said electrode comprising a light-transmissive electrode including an oxide semiconductor, and a positive contact electrode electrically connected to said light-transmissive electrode,

wherein an area of said positive contact electrode is less than ½ of an area of said upper surface of said p-type layer, and

wherein said negative electrode includes a light-transmissive ohmic electrode and a metallic contact electrode partially formed on a surface of said light-transmissive ohmic electrode.

14. The light emitting device of claim 13 , wherein said area of said positive contact electrode is less than ⅓ of said area of said upper surface of said p-type layer.

15. The light emitting device of claim 14 , wherein said area of said positive contact electrode is less than ¼ of said area of said upper surface of said p-type layer.

16. The light emitting device of claim 13 , wherein said GaN-based LED chip is encapsulated with a resin.

17. The light emitting device of claim 13 , wherein said light-transmissive electrode has a planarized surface, said planarized surface being planarized by polishing.

18. The light emitting device of claim 13 , wherein said light-transmissive substrate is an n-type conductive semiconductor single crystal substrate.

19. The light emitting device of claim 18 , wherein said light-transmissive substrate is a silicon carbide, zinc oxide, GaN or AlGaN.

20. The light emitting device of claim 13 , wherein said positive contact electrode is a single layer film or multi-layer film having, at least on a side in contact with said light-transmissive electrode, a layer made of Al, Ag, Rh or Pt or an alloy made from at least one of Al, Ag, Rh and Pt.

21. The light emitting device of claim 13 , further comprising an insulating protective film applied so as to coat a surface of said light-transmissive electrode, said film having a surface with higher planarity than a planarity of said surface of said light-transmissive electrode.

22. The light emitting device of claim 13 , wherein said positive contact electrode includes

a part bonded to a base, and

a current diffusion part extending from said part on said light-transmissive electrode.