Patent ID: 7629237

Claim:
A method of growing a semiconductor layer structure, the method comprising the steps of: growing a first (Al,Ga)N layer over a substrate at a first substrate temperature within the range 850° C. to 1050° C. by MBE using ammonia as the nitrogen precursor; cooling the substrate to a second substrate temperature lower than the first substrate temperature within the range 650° C. to 1000° C., while maintaining the supply of ammonia to the substrate; growing an (In,Ga)N quantum well structure over the first (Al,Ga)N layer by MBE using ammonia as the nitrogen precursor; heating the substrate to a third substrate temperature higher than the second substrate temperature within the range 850° C. to 1050° C., while maintaining the supply of ammonia to the substrate; and growing a second (Al,Ga)N layer over the quantum well structure at the third substrate temperature by MBE using ammonia as the nitrogen precursor, wherein the ratio of the supplied ammonia to supplied elemental metal is within the range 10:1 to 10,000:1.