Patent ID: 7566579

Claim:
A method of fabricating a semiconductor layer in the InAlGaN material system on a gallium-rich group III nitride layer, the method comprising: growing a Al x In y Ga 1-x-y N fabrication facilitation layer on a first surface of the gallium-rich group III nitride layer, growing at least one further layer in the InAlGaN material system above the fabrication facilitation layer while growth rate information is determined optically, wherein x and y are so as to provide lattice match with the gallium rich group III nitride layer such that the in plane strain is less than +/−1% and wherein the Al x In y Ga 1-x-y N layer is so as to provide a detectable refractive index contrast with the at least one further layer in the AlInGaN material system or the first gallium-rich group III nitride layer.