High mobility two-dimensional electron gas in AlGaN GaN heterostructures grown by plasma-assisted molecular beam epitaxy

High quality AlGaN/GaN heterostructures have been grown by radio-frequency plasma-assisted molecular beam epitaxy on n-type GaN templates grown on sapphire by metal organic chemical vapor deposition. The unintentionally doped Al0.12Ga0.88N/GaN heterostructure exhibits a 77 K Hall mobility of 14 500 cm(2)/Vs and a 12 K mobility of 20 000 cm(2)/Vs (n(s) = 5.0 X 10(12) cm(-2)). A room temperature mobility of 1860 cm(2)/Vs (n(s) = 4.8 X 10(12) cm(-2)) was calculated for the two-dimensional electron gas channel using a two layer model from the measured mobility for the whole structure (template plus heterostructure). Magnetoresistance measurements at 4.2 K showed well-resolved Shubnikov-de Haas oscillations, which began at 2.6 T. (C) 1999 American Institute of Physics. [S0003-6951(99)00223-5].