Semiconductor device having a buffer structure for eliminating defects from a semiconductor layer grown thereon

Claim 1

A semiconductor device, comprising: a substrate of a semiconductor material and having upper and lower major surfaces; a buffer layer comprising first and second layers of respective group III-V compound semiconductor materials, each of said first and second layers having respective upper and lower major surfaces, said lower surface of said first layer being formed on said upper surface of said substrate and said lower surface of said second layer being formed on said upper surface of said first layer, said group III-V compound semiconductor material of said second layer comprising first and second, different, group III elements and a group V element, said second group III element having a concentration level distribution in said second layer varying from a minimum concentration level at each of said upper and lower major surfaces thereof to a maximum concentration level between said upper and lower major surfaces thereof; a device layer having upper and lower major surfaces and formed with said lower surface thereof on said upper surface of said second layer of said buffer layer, said device layer comprising a group III-V compound semiconductor material and having an active device formed in said upper surface thereof; and said buffer layer intercepting defects, originating at and propagating from the upper major surface of the substrate and into the buffer layer, and thereby suppressing further propagation of said defects into device layer.