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

Abstract

We study the effect of a combination of N2 and H2 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 H2 or N2 carrier gas (H2– or N2–GaN) on an AlN low-temperature-deposited buffer layer. A (0001) sapphire substrate was used. N2–GaN was grown on H2–GaN. The total thickness was set to be 1.5 μm, and the ratio of N2–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 N2 on H2–GaN than when it was grown with H2 on H2–GaN. These results were due to the achievement of control of strain in GaN using a combination of N2–GaN and H2–GaN.