Nitride semiconductor element having
View Patent ↗A nitride-based semiconductor device of the present invention includes: a nitride-based semiconductor multilayer structure 20 which includes a p-type semiconductor region with a surface 12 being inclined from the m-plane by an angle of not less than 1° and not more than 5°; and an electrode 30 provided on the p-type semiconductor region. The p-type semiconductor region is formed by an Al x In y Ga z N (where x+y+z=1, x≧0, y≧0, and z≧0) layer 26 . The electrode 30 includes a Mg layer 32 and an Ag layer 34 provided on the Mg layer 32 . The Mg layer 32 is in contact with the surface 12 of the p-type semiconductor region of the semiconductor multilayer structure 20.
1. A nitride-based semiconductor device, comprising:
a nitride-based semiconductor multilayer structure including a p-type GaN-based semiconductor region; and
an electrode that is arranged on the p-type GaN-based semiconductor region,
wherein in the p-type GaN-based semiconductor region, an angle formed by a normal to a principal surface and a normal to an m-plane is not less than 1° and not more than 5°,
the electrode includes a Mg layer which is in contact with the principal surface of the p-type GaN-based semiconductor region and a Ag layer which is provided on the Mg layer, and
in the Mg layer, a concentration of N is lower than a concentration of Ga.
2. The nitride-based semiconductor device of claim 1 , wherein the p-type GaN-based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z≧0).
3. The nitride-based semiconductor device of claim 1 , wherein the Ag layer is covered with a protector electrode which is made of a metal different from Ag.
4. The nitride-based semiconductor device of claim 1 , wherein the Ag layer is covered with a protector layer which is made of a dielectric.
5. The nitride-based semiconductor device of claim 1 , wherein the nitride-based semiconductor multilayer structure includes an active layer which includes an Al a In b Ga c N layer (where a+b+c=1, a≧0, b≧0 and c≧0), the active layer being configured to emit light.
6. The nitride-based semiconductor device of claim 1 , wherein a thickness of the Mg layer is equal to or smaller than a thickness of the Ag layer.
7. The nitride-based semiconductor device of claim 1 , further comprising a semiconductor substrate that supports the nitride-based semiconductor multilayer structure.
8. The nitride-based semiconductor device of claim 1 , wherein the p-type GaN-based semiconductor region is made of GaN.
9. The nitride-based semiconductor device of claim 1 , wherein a Mg—Ag alloy layer is provided between the Mg layer and the Ag layer.
10. The nitride-based semiconductor device of claim 1 , wherein the Mg layer is in the form of islands.
11. The nitride-based semiconductor device of claim 1 , wherein the Mg layer is made of a Mg—Ag alloy.
12. The nitride-based semiconductor device of claim 1 , wherein the Mg layer is in contact with the Ag layer.
13. The nitride-based semiconductor device of claim 1 , wherein the nitride-based semiconductor device has a light extraction surface on a side opposite to the electrode with the nitride-based semiconductor multilayer structure being interposed therebetween.
14. The nitride-based semiconductor device of claim 1 , wherein a contact resistance of the electrode is lower than a contact resistance when the electrode is arranged on a c-plane.
15. The nitride-based semiconductor device of claim 1 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −2 Ω cm 2 .
16. A light source, comprising:
a nitride-based semiconductor light-emitting device; and
a wavelength converter including a phosphor that converts a wavelength of light emitted from the nitride-based semiconductor light-emitting device,
wherein the nitride-based semiconductor light-emitting device includes
a nitride-based semiconductor multilayer structure including a p-type GaN-based semiconductor region, and
an electrode that is arranged on the p-type GaN-based semiconductor region,
in the p-type GaN-based semiconductor region, an angle formed by a normal to a principal surface and a normal to an m-plane is not less than 1° and not more than 5°,
the electrode includes a Mg layer which is in contact with the principal surface of the p-type GaN-based semiconductor region and a Ag layer which is provided on the Mg layer, and
the Mg layer, a concentration of N is lower than a concentration of Ga.
17. The light source of claim 16 , wherein the p-type GaN-based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z≧0).
18. The light source of claim 16 , wherein the p-type GaN-based semiconductor region is made of GaN.
19. The light source of claim 16 , wherein a Mg—Ag alloy layer is provided between the Mg layer and the Ag layer.
20. The light source of claim 16 , wherein the Mg layer is in contact with the Ag layer.
21. The light source of claim 16 , wherein the nitride-based semiconductor light-emitting device has a light extraction surface on a side opposite to the electrode with the nitride-based semiconductor multilayer structure being interposed therebetween.
22. The light source of claim 16 , wherein a contact resistance of the electrode is lower than a contact resistance when the electrode is arranged on a c-plane.
23. The light source of claim 16 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −02 Ω cm 2 .
24. A method for fabricating a nitride-based semiconductor device, comprising the steps of:
(a) providing a substrate;
(b) forming on the substrate a nitride-based semiconductor multilayer structure including a p-type GaN-based semiconductor region in which an angle formed by a normal to a principal surface and a normal to an m-plane is not less than 1° and not more than 5°; and
(c) forming an electrode on the principal surface of the p-type GaN-based semiconductor region of the nitride-based semiconductor multilayer structure,
wherein step (c) includes
forming a Mg layer on the principal surface of the p-type GaN-based semiconductor region, and
forming a Ag layer on the Mg layer, and
in the Mg layer, a concentration of N is lower than a concentration of Ga.
25. The method source of claim 24 , wherein the p-type GaN-based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z≧0).
26. The method of claim 24 , wherein step (c) further includes performing a heat treatment on the Mg layer.
27. The method of claim 26 , wherein the heat treatment is performed at a temperature of 500° C. to 700° C.
28. The method of claim 27 , wherein the heat treatment is performed at a temperature of 550° C. to 600° C.
29. The method of claim 24 , wherein the step of forming the Mg layer includes irradiating Mg with pulses of an electron beam such that Mg is deposited onto the principal surface of the p-type GaN-based semiconductor region.
30. The method of claim 24 , further comprising removing the substrate after step (b).
31. The method of claim 24 , wherein the p-type GaN-based semiconductor region is made of GaN.
32. The method of claim 24 , wherein the Mg layer and the Ag layer are at least partially to be alloyed.
33. The method of claim 24 , wherein the Mg layer is in contact with the Ag layer.
34. The method of claim 24 , wherein the nitride-based semiconductor device has a light extraction surface on a side opposite to the electrode with the nitride-based semiconductor multilayer structure being interposed therebetween.
35. The method of claim 24 , wherein a contact resistance of the electrode is lower than a contact resistance when the electrode is arranged on a c-plane.
36. The method of claim 24 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −02 Ω cm 2 .
37. A nitride-based semiconductor device, comprising:
a nitride-based semiconductor multilayer structure including a p-type GaN-based semiconductor region; and
an electrode that is arranged on the p-type GaN-based semiconductor region,
wherein in the p-type GaN-based semiconductor region, an angle formed by a normal to a principal surface and a normal to an m-plane is not less than 1° and not more than 5°, and
the electrode is composed only of an alloy layer which is in contact with the principal surface of the p-type GaN-based semiconductor region, and
the alloy layer is made of Mg and Ag, and
in the alloy layer, a concentration of N is lower than a concentration of Ga.
38. The nitride-based semiconductor device of claim 37 , wherein the p-type GaN-based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z≧0).
39. The nitride-based semiconductor device of claim 37 , wherein the alloy layer is formed by forming a Mg layer so as to be in contact with the principal surface of the p-type GaN-based semiconductor region and a Ag layer on the Mg layer, and thereafter performing a heat treatment.
40. The nitride-based semiconductor device of claim 37 , wherein the alloy layer is formed by depositing a mixture or compound of Mg and Ag onto the principal surface of the p-type GaN-based semiconductor region by means of evaporation, and thereafter performing a heat treatment.
41. The nitride-based semiconductor device of claim 37 , wherein a contact resistance of the electrode is lower than a contact resistance when the electrode is arranged on a c-plane.
42. The nitride-based semiconductor device of claim 37 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −02 Ω cm 2 .