Patent ID: 7566576

Claim:
A method of making a light-emitting semiconductor device of improved efficiency, which comprises: (a) providing a light-generating semiconductor region having a first major surface from which light is emitted and a second major surface which is opposite to the first major surface, the light-generating semiconductor region comprising a plurality of compound semiconductor layers including a gallium-containing compound semiconductor layer which is exposed at the second major surface of the semiconductor region; (b) creating a transition metal layer containing a transition metal on at least part of the second major surface of the light-generating semiconductor region; (c) creating a diffusible metal layer on the transition metal layer, the diffusible metal layer containing a metal that can be thermally diffused into the gallium-containing compound semiconductor layer of the light-generating semiconductor region through the transition metal layer; (d) creating an ohmic contact region in the gallium-containing compound semiconductor layer of the light-generating semiconductor region by causing thermal diffusion of the diffusible metal from the diffusible metal layer into the gallium-containing compound semiconductor layer through the transition metal layer at a temperature less than the eutectic point of elements constituting the gallium-containing compound semiconductor layer and the diffusible metal; (e) removing the transition metal layer and the diffusible metal layer from the light-generating semiconductor region; and (f) creating a reflective layer of electrically conducting material on at least either of the ohmic contact region and that part, if any, of the gallium-containing compound semiconductor layer of the light-generating semiconductor region which is exposed at the second major surface of the semiconductor region through the ohmic contact region.