Control of strain in GaN by a combination of H2 and N2 carrier gases

We study the effect of a combination of N-2 and H-2 carrier gases on the residual strain and crystalline properties of GaN, and we propose its application to the improvement of crystalline quality of GaN/Al0.17Ga0.83N multiple quantum well (MQW) structures. GaN was grown with H-2 or N-2 carrier gas (H-2- or N-2-GaN) on an AlN low-temperature-deposited buffer layer. A (0001) sapphire substrate was used. N-2-GaN was grown on H-2-GaN. The total thickness was set to be 1.5 mum, and the ratio of N-2-GaN thickness to the total thickness, x, ranged from 0 to 1. With increasing x, the tensile stress in GaN increased. Photoluminescence intensity at room temperature was much enhanced. Moreover, the crystalline quality of GaN/Al0.17Ga0.83N MQW was much higher when the MQW was grown with N-2 on H-2-GaN than when it was grown with H-2 on H-2-GaN. These results were due to the achievement of control of strain in GaN using a combination of N-2-GaN and H-2-GaN. (C) 2001 American Institute of Physics.