Patent ID: 7456034

Claim:
A method for fabricating a nitride semiconductor device which includes a well layer provided above a substrate, a plurality of barrier layers sandwiching the well layer to construct a quantum well, and a first thin film layer provided on one of the plurality of barrier layers and under the well layer, the method comprising: the step (a) of depositing nitride semiconductor containing Al and Ga above the substrate at a substrate temperature T 1 , thereby forming one of the plurality of barrier layers; the step (b) of depositing, on one said barrier layer, nitride semiconductor having a smaller band gap energy than one said barrier layer, thereby forming the first thin film layer; the step (c) of depositing nitride semiconductor on the first thin film layer at a substrate temperature T 2 (where T 1 >T 2 ) to form the well layer, the nitride semiconductor containing In and Ga and having a smaller band gap energy than the first thin film layer; and the step (d) of depositing nitride semiconductor on or above the well layer at a substrate temperature T 3 (where T 3 >T 2 ) to form another one of the plurality of barrier layers, the nitride semiconductor containing Al and Ga and having a larger band gap energy than the first thin film layer and the well layer, wherein the T 1 and T 3 are higher than a substrate temperature of the step (b).