Patent ID: 7498609

Claim:
A light-emitting semiconductor device of improved efficiency, comprising: (a) a light-generating semiconductor region comprising a plurality of compound semiconductor layers for generating light, the light-generating semiconductor region having a first major surface from which is emitted the light, and a second major surface opposite to the first major surface, the light-generating semiconductor region having a gallium-based compound semiconductor layer which is exposed at the second major surface of the light-generating semiconductor region; (b) an electrode on the first major surface of the light-generating semiconductor region; (c) an ohmic contact layer formed on part of the second major surface of the light-generating semiconductor region in ohmic contact therewith, the ohmic contact layer being of an alloy of gallium and another metal, and the alloy being free from germanium; (d) a reflective metal layer covering the second major surface of the light-generating semiconductor region via the ohmic contact layer for reflecting the light from the light-generating semiconductor region toward the first major surface thereof; and (e) a transparent anti-alloying layer interposed between the light-generating semiconductor region and the reflective metal layer so as to cover at least part of that part of the second major surface of the light-generating semiconductor region which is left exposed by the ohmic contact layer, in order to prevent the alloying of the light-generating semiconductor region and the reflective metal layer; (f) whereby a greater percentage of the light from the light-generating semiconductor region is reflected by the reflective metal layer for emission from the first major surface of the light-generating semiconductor region than in the absence of the anti-alloying layer.