Patent ID: 7897497

Claim:
A method of making an overvoltage-protected light-emitting semiconductor device, which comprises the steps of: (a) providing a silicon substrate having an overvoltage protector section and an LED section each extending between a first and a second opposite major surface thereof, the substrate having an n-type semiconductor region formed in the overvoltage protector section of the substrate to a prescribed depth from the first major surface thereof and a p-type semiconductor region in the rest of the substrate; (b) creating a light-generating semiconductor region on the first major surface of the substrate by successively growing by epitaxy a first compound semiconductor layer of a first conductivity type and a second compound semiconductor layer of a second conductivity type, the first compound semiconductor layer of the light-generating semiconductor region containing a Group III element; (c) concurrently with step (b), there being created a p-type impurity-diffused layer in the substrate by thermal diffusion dispersion of the Group III element from the first compound semiconductor layer of the light-generating semiconductor region as a by-product of the epitaxial growth of the light-generating semiconductor region on the substrate, the p-type impurity-diffused layer of the substrate being created to a depth less than the depth of the n-type semiconductor region of the substrate from the first major surface of the substrate; (d) exposing the first major surface of the overvoltage protector section of the substrate by removing part of the light-generating semiconductor region from over the voltage protector section of the substrate; (e) creating a trench in the first major surface of the substrate thereby electrically separating the p-type impurity-diffused layer of the substrate into an overvoltage protector part contained in the overvoltage protector section of the substrate and an LED part contained in the LED section of the substrate, a pn-junction between the overvoltage protector part of the p-type impurity-diffused layer and the n-type semiconductor region of the substrate and another pn-junction between the p-type semiconductor region and n-type semiconductor region of the substrate being both peripherally exposed at the trench; (f) creating a first electrode electrically coupled both to the second compound semiconductor layer of the light-generating semiconductor region on the LED section of the substrate and to the overvoltage protector part of the p-type impurity-diffused layer of the substrate; and (g) creating a second electrode electrically coupled to the p-type semiconductor region of the substrate.