Patent ID: 7186620

Claim:
A method of making a substrate system for fabrication of a semiconductor device, which comprises: (a) providing a baseplate; (b) forming a first layer on the baseplate by growing by vapor-phase epitaxy a gallium-nitride-based compound semiconductor containing aluminum in a first proportion which is equal to or greater than zero; (c) forming a second layer on the first layer by growing by vapor-phase epitaxy a nitride semiconductor containing aluminum in a second proportion which is greater than the first proportion, with substantially concurrent creation of interstices in the first layer; (d) removing at least part of the second layer from over the first layer; and (e) forming a third layer on the first layer by growing a gallium-nitride-based compound semiconductor by vapor-phase epitaxy, the third layer being constituted of a first portion filling the interstices in the first layer and of a second portion joined to the first portion.