Effect of strain on the effective mass of GaN and the mobility of AlGaN/GaN two-dimensional electron gas

By performing first-principles calculations based on density functional theory, we have investigated the effect of strain on the effective mass of GaN and the two-dimensional (2D) electron gas mobility of AlGaN/GaN. Our calculated results predict that the effective mass of GaN under strain decreases with increasing tensile strain while increases with increasing compressive strain. The 2D electron gas mobility increases with increasing tensile strain and decreases with increasing compressive strain at constant surface density, reaching a value of 3.40 x 10(3) cm(2)/V center dot s under the tensile strain of 5 %. However, the 2D electron gas mobility decreases with increasing surface density, and reaching a value of 3.05 x 10(3) cm(2)/V center dot s at a surface density of 1.0 x 10(12) cm(-2). It is expected that our results will serve as a guide to improve the electrical properties of AlGaN/GaN HEMTs.