High-conductivity n-AlGaN with high Al mole fraction grown by metalorganic vapor phase deposition

Highly-conductive and crack-free n-Al0.6Ga0.4N films with thickness up to 1 mum were achieved by using high-temperature AlN or AlGaN/AlN superlattice (SL) buffer layers. Room-temperature Hall measurements show the highest electron concentration of 3.5x10(18) cm(-3) with mobility of 25 cm(2)/V s. Electron mobility was increased from 25 to 35 cm(2)/V s by introducing the AlGaN/AlN SL buffer layer. Second ion mass spectroscopy indicates that there is high oxygen doping concentration in the film, and that the film resistivity decreases with increasing oxygen concentration from 1x10(17) to similar to1x10(19) cm(-3). (C) 2003 American Institute of Physics.