Thin film electrode for forming ohmic contact in light emitting diodes and laser diodes using nickel-based solid solution for manufacturing high performance gallium nitride-based optical devices, and method for fabricating the same
View Patent ↗Disclosed herein is a technique for forming a high quality ohmic contact utilizable in the fabrication of short-wavelength light emitting diodes (LEDs) emitting blue and green visible light and ultraviolet light, and laser diodes (LDs) using a gallium nitride (GaN) semiconductor. The ohmic contact is formed by depositing a nickel (Ni)-based solid solution on top of a p-type gallium nitride semiconductor. The ohmic contact thus formed has an excellent current-voltage characteristic and a low specific contact resistance due to an increased effective carrier concentration around the surface of the gallium nitride layer, as well as a high transmittance in the short-wavelength region.
1. A thin film electrode for forming an ohmic contact in light emitting diodes or laser diodes, comprising: a first electrode layer laminated on a p-type gallium nitride layer and including a Ni—X solid solution; and a second electrode layer laminated on the first electrode and including at least one element selected from the group consisting of Pd, Ni, Ru, Rh, Re, C, Cu and Ir.
2. The thin film electrode according to claim 1 , wherein the p-type gallium nitride has a composition of Al x ln y Ga z N (where 0<x<1, 0<y<1, 0<z<1, and x+y+z=1).
3. A thin film electrode, comprising
a first electrode layer laminated on a p-type gallium nitride layer and including a Ni—X solid solution;
a second electrode layer laminated on the first electrode and including at least one element selected from the group consisting of Au, Pt, Pd, Ni, Ru, Rh, Re, C, Cu and Ir; and
a third electrode layer laminated on the second electrode layer and including at least one element selected from the group consisting of Al, Ag and Rh.
4. The thin film electrode according to claim 3 , wherein the third electrode layer laminated on the second electrode layer includes at least one element selected from the group consisting of transparent conductive oxides and transparent conductive nitrides.
5. The thin film electrode according to claim 4 , further comprising a fourth electrode layer laminated on the third electrode layer and including at least one element selected from the group consisting of Al, Ag and Rh.
6. A thin film electrode for forming an ohmic contact in light emitting diodes or laser diodes, comprising: a first electrode layer laminated on a p-type gallium nitride layer and including at least one element selected from the group consisting of Au, Pt, Pd, Ni, Ru, Rh, Re, C, Cu and Ir; and a second electrode layer laminated on the first electrode and including a Ni—X solid solution, wherein the Ni-based (Ni—X) solid solution includes nickel (Ni) as a matrix metal, and X including at least one element selected from the group consisting of group II elements, group VI elements, Sc, Y, Ge, Sn and Sb.
7. A thin film electrode for forming an ohmic contact in light emitting diodes or laser diodes, comprising
a first electrode layer laminated on a p-type gallium nitride layer and including at least one element selected from the group consisting of Au, Pt, Pd, Ni, Ru, Rh, Re, C, Cu and Ir;
a second electrode layer laminated on the first electrode and including a Ni—X solid solution; and
a third electrode layer laminated on the second electrode layer and comprising at least one element selected from the group consisting of Al, Ag and Rh.
8. The thin film electrode according to claim 7 , wherein the third electrode layer laminated on the second electrode layer comprises at least one compound selected from the group consisting of transparent conductive oxides and transparent conductive nitrides, and further comprising a fourth electrode layer laminated on the third electrode layer and comprising at least one element selected from the group consisting of Al, Ag and Rh.
9. The thin film electrode according to claim 8 , wherein the electrode layers formed from the Ni-based solid solution have a thickness of 1~1,000 Å, and the first, the second, the third, and the fourth electrode layers have an overall thickness of 1~50,000 Å.
10. A thin film electrode for forming an ohmic contact in light emitting diodes or laser diodes, comprising: a first electrode layer laminated on a p-type gallium nitride layer and including a Ni—X solid solution; and a second electrode layer laminated on the first electrode and including at least one transparent conductive nitride.
11. The thin film electrode according to claim 10 , further comprising a third electrode layer laminated on the second electrode layer and including at least one element selected from the group consisting of Al, Ag and Rh.
12. A thin film electrode for forming an ohmic contact in light emitting diodes or laser diodes, comprising: a first electrode layer laminated on a p-type gallium nitride layer and including a Ni—X solid solution; and a second electrode layer laminated on the first electrode layer and including at least one element selected from the group consisting of Al, Ag and Rh, wherein the Ni-based (Ni—X) solid solution includes nickel (Ni) as a matrix metal, and X including at least one element selected from the group consisting of group II elements, group VI elements, Sc, Y, Ge, Sn and Sb.
13. The thin film electrode according to claim 12 , wherein the group II elements include one element selected from the group consisting of Mg, Be, Ca and Zn.
14. The thin film electrode according to claim 12 , wherein the group VI elements include one element selected from the group consisting of S, Se and Te.
15. The thin film electrode according to claim 12 , wherein the X element constituting the Ni-based (Ni—X) solid solution is added in the amount of 1~49 atomic percent (%).