Impact of residual carbon on two-dimensional electron gas properties in Al_xGa_1-x)N/GaN heterostructure

摘要

High tuneability of residual carbon doping is developed in a hot-wall metalorganic chemical vapor deposition reactor. Two orders of temperature-tuned carbon concentration, from ～2 × 10~(18)cm~(-3) down to ～1 × 10~(16)cm~(-3), can be effectively controlled in the growth of the GaN buffer layer. Excellent uniformity of two-dimensional electron gas (2DEG) properties in Al_xGa_(1-x)N/AIN/GaN heterostructure with very high average carrier density and mobility, 1.1 × 10~(13)cm~(-2)and 2035 cm~2/V·s, respectively, over 3" semi-insulating SiC substrate is realized with the temperature-tuned carbon doping scheme. Reduction of carbon concentration is evidenced as a key to achieve high 2DEG carrier density and mobility.