Semiconductor light-emitting device and method for making same

1. A semiconductor light-emitting device, comprising:

an upper cladding layer;

a lower cladding layer;

an active layer between the upper and lower cladding layers;

an upper ohmic-contact layer forming a conductive path to the upper cladding layer; and

a lower ohmic-contact layer forming a conductive path to the lower cladding layer, the lower ohmic-contact layer having a shape that is substantially complementary to the shape of the upper ohmic-contact layer, wherein the lower ohmic-contact layer is formed by removing a portion that is substantially overlapping vertically with the upper ohmic-contact layer, thereby diverting a carrier flow away from a portion of the active layer which is substantially below the upper ohmic-contact layer when a voltage is applied to the upper and lower ohmic-contact layers:

wherein the removed portion of the lower ohmic-contact layer is filled with a metal material capable of forming a Schottky contact with the lower cladding layer.

2. The semiconductor light-emitting device of claim 1 , wherein the material contained in the region where the lower ohmic-contact layer is not present comprises one of: Au, Al, and Ag.

3. The semiconductor light-emitting device of claim 2 , wherein the material contained in the region where the lower ohmic-contact layer is not present is reflective with regard to the wavelength of the light emitted by the active layer.

4. The semiconductor light-emitting device of claim 1 , further comprising a layer of insulating material situated between the lower cladding layer and the lower ohmic-contact layer; and

wherein the insulating material is confined to a region substantially below the upper ohmic-contact layer, thereby resulting in majority of carrier recombination occurring in active-layer regions where upward-propagating light is not obstructed by the upper ohmic-contact layer.

5. The semiconductor light-emitting device of claim 1 , further comprising a bonding-material layer below the lower ohmic-contact layer and a low-resistance substrate below the bonding-material layer;

wherein the low-resistance substrate comprises Si;

wherein the upper and lower cladding layers comprise n-type GaN and p-type GaN, respectively;

wherein the active layer comprises an InGaN/GaN multi-quantum-well structure; and

wherein the bonding-material layer comprises Au.

6. A semiconductor light-emitting device, comprising:

an upper cladding layer;

a lower cladding layer;

an active layer between the upper and lower cladding layers;

an upper ohmic-contact layer forming a conductive path to the upper cladding layer; and

a lower ohmic-contact layer forming a conductive path to the lower cladding layer;

wherein the shape of the lower cladding layer, which is in direct contact with the lower ohmic-contact layer, is substantially complementary to the shape of the upper ohmic-contact layer, wherein the complementary shape of the lower cladding layer is formed by removing a portion of the lower cladding layer that is substantially overlapping vertically with the upper ohmic-contact layer, and wherein the removed portion is filled with an insulating material, thereby resulting in majority of carrier recombination occurring in active-layer regions where upward-propagating light is not obstructed by the upper ohmic-contact layer.

7. A method for fabricating a semiconductor light-emitting device, the method comprising:

forming a layered semiconductor structure on a growth substrate, the layered semiconductor structure comprising:

an n-type semiconductor layer;

an active layer; and

a p-type semiconductor layer;

forming a first ohmic-contact layer with a conductive path to a first side of the layered structure;

removing a portion of the first ohmic-contact layer;

forming a bonding-material layer over the first ohmic-contact layer;

bonding a low-resistance substrate onto the bonding-material layer;

removing the growth substrate to expose a second side of the layered structure; and

forming a second ohmic-contact layer with a conductive path to the second side of the layered structure, wherein the second ohmic-contact layer is confined within a region which substantially corresponds to the region where the portion of the first ohmic-contact layer is removed, wherein the shape of the second ohmic-contact layer is substantially complementary to the shape of the first ohmic-contact layer; and

filling the region where the portion of the first ohmic-contact layer is removed with an insulating material, wherein the shape of the filled region is substantially the same as the shape of the second ohmic-contact layer, thereby diverting carrier flow away from a portion within the active layer where vertically emitted light can be substantially obstructed by the second ohmic-contact layer.

8. The method of claim 7 , wherein the material used to fill the region where the portion of the first ohmic-contact layer is removed comprises SiO2.

9. The method of claim 7 , wherein the first ohmic-contact layer comprises a material that is reflective with regard to the wavelength of the light emitted by the active layer.

10. A method for fabricating a semiconductor light-emitting device, the method comprising:

forming a layered semiconductor structure above a growth substrate, the layered semiconductor structure comprising:

an n-type semiconductor layer;

an active layer; and

a p-type semiconductor layer;

removing a portion of the p-type layer and/or the active layer;

filling the region where the p-type layer and/or the active layer is removed with an insulating material;

forming a first ohmic-contact layer with a conductive path to the first side of the layered structure, the first ohmic-contact layer covering the insulating-material region;

forming a bonding-material layer over the first ohmic-contact layer;

bonding a low-resistance substrate onto the bonding-material layer;

removing the growth substrate to expose a second side of the layered structure; and

forming a second ohmic-contact layer with a conductive path to the second side of the layered structure, the second ohmic-contact layer confined within a region which substantially corresponds to the insulating-material region, and wherein the shape of the second ohmic-contact layer is substantially the same as the shape of the insulating-material region, thereby diverting carrier flow away from a portion within the active layer where vertically emitted light can be substantially obstructed by the second ohmic-contact layer.

11. The method of claim 10 , wherein the insulating-material region penetrates the p-type layer.