Effects of pressure and NH3 flow on the Two-dimensional electron mobility in AlGaN/GaN heterostructures

The dependence of the two-dimensional electron gas mobility in AlGaN/GaN heterostructures on the growth conditions of the AlGaN films grown by using metalorganic chemical-vapor deposition was investigated. X-ray reflectivity and X-ray diffraction measurements revealed that the growth pressure and the NH3 flow rate during the deposition of the AlGaN layer critically influenced the interface roughness between the AlGaN and the GaN layers and the stacking order of the AlGaN layer in the growth direction. The Al0.15Ga0.85N/GaN heterostructure grown at a low pressure and a high NH3 flow rate showed an abrupt interface and an enhanced stacking order in the film, resulting in an increase in the two-dimensional electron gas mobility up to 1340 cm2/V·s at 130 K