Semiconductor light-emitting device with a highly reflective ohmic-electrode
A semiconductor light-emitting device includes a multilayer semiconductor structure on a conductive substrate. The multilayer semiconductor structure includes a first doped semiconductor layer situated above the conductive substrate, a second doped semiconductor layer situated above the first doped semiconductor layer, and/or an MQW active layer situated between the first and second doped semiconductor layers. The device also includes a reflective ohmic-contact metal layer between the first doped semiconductor layer and the conductive substrate, which includes Ag, and at least one of: Ni, Ru, Rh, Pd, Au, Os, Ir, and Pt; plus at least one of: Zn, Mg Be, and Cd; and a number of: W, Cu, Fe, Ti, Ta, and Cr. The device further includes a bonding layer between the reflective ohmic-contact metal layer and the conductive substrate, a first electrode coupled to the conductive substrate, and a second electrode coupled to the second doped semiconductor layer.
1. A semiconductor light-emitting device, comprising:
a multilayer semiconductor structure on a conductive substrate, the multilayer semiconductor structure comprising a first doped semiconductor layer situated above the conductive substrate, a second doped semiconductor layer situated above the first doped semiconductor layer, and/or a multi-quantum-wells (MQW) active layer situated between the first and second doped semiconductor layers;
a reflective ohmic-contact metal layer situated between the first doped semiconductor layer and the conductive substrate, wherein the reflective ohmic-contact metal layer comprises one of the following metal compositions:
Ag/Pt/Mg, and
Ag/Pt/Zn;
a bonding layer situated between the reflective ohmic-contact metal layer and the conductive substrate;
a first electrode coupled to the conductive substrate; and
a second electrode on the second doped semiconductor layer.
2. The semiconductor light-emitting device of claim 1 ,
wherein the first doped semiconductor layer is a p-type doped semiconductor layer.
3. The semiconductor light-emitting device of claim 2 ,
wherein the p-type doped semiconductor layer comprises GaN doped with Mg.
4. The semiconductor light-emitting device of claim 1 ,
wherein the reflective ohmic-contact layer comprises by weight:
97% of Ag;
1.5% of Pt; and
1.5% of Zn.
5. The semiconductor light-emitting device of claim 1 ,
wherein the MQW active layer comprises at least one of the following materials:
InGaN,
InGaAlN,
InGaAlP, and
InGaAlAs.
6. The semiconductor light-emitting device of claim 1 ,
wherein the conductive substrate comprises at least one of the following materials:
Si,
GaAs,
GaP,
Cu, and
Cr.
7. A method for fabricating a semiconductor light-emitting device, the method comprising:
growing a multilayer semiconductor structure on a growth substrate, wherein the multilayer semiconductor structure comprises a first doped semiconductor layer, a second doped semiconductor layer, and/or a multi-quantum-wells (MQW) active layer;
forming a reflective ohmic-contact metal layer on the first doped semiconductor layer, wherein the reflective ohmic-contact metal layer comprises one of the following metal compositions:
Ag/Pt/Mg, and
Ag/Pt/Zn;
forming a bonding layer coupled to the reflective ohmic-contact metal layer;
bonding the multilayer structure to a conductive substrate;
removing the growth substrate;
forming a first electrode coupled to the conductive substrate; and
forming a second electrode on the second doped semiconductor layer.
8. The method of claim 7 ,
wherein the growth substrate comprises a pre-defined pattern of grooves and mesas.
9. The method of claim 7 , further comprising:
forming a contact-assist metal layer on the first doped semiconductor layer, wherein the contact-assist metal layer comprises Pt or a Pt alloy which includes at least one of the following materials: Ru, Rh, Pd, Os, Ir, Ni, Zn, and Mg;
annealing the multilayer structure to activate the first doped semiconductor layer; and
removing the contact-assist metal layer.
10. The method of claim 7 ,
wherein the first doped semiconductor layer is a p-type doped semiconductor layer.
11. The method of claim 10 ,
wherein the p-type doped semiconductor layer comprises GaN doped with Mg.
12. The method of claim 9 ,
wherein the thickness of the contact-assist metal layer is at least 10 angstroms.
13. The method of claim 9 ,
wherein temperature for the annealing process is between 200° C. and 1000° C.;
wherein the duration for the annealing process is approximately 5 minutes; and
wherein the annealing atmosphere comprises one of the following:
N 2 ,
O 2 ,
air,
vacuum, and
inert gases.
14. The method of claim 9 ,
wherein the removal of the contact-assist metal layer involves chemical etching and/or mechanical grinding.
15. The method of claim 7 ,
wherein the reflective ohmic-contact layer comprises by weight:
97% of Ag;
1.5% of Pt; and
1.5% of Zn.
16. The method of claim 7 ,
wherein the conductive substrate comprises at least one of the following materials:
Si,
GaAs,
GaP,
Cu, and
Cr.