Metalorganic Chemical Vapor Deposition Conditions for Efficient Silicon Doping in High Al-Composition AlGaN Films

The influence of the metalorganic chemical vapor deposition conditions on the electrical and optical properties was investigated for silicon-doped Al x Ga 1- x N films with x >0.5 grown on sapphire and 6H–SiC substrates. At a constant silicon concentration in the layers, the electron carrier concentration was the highest in films deposited at reduced temperatures and high V/III ratios, despite the higher residual carbon and oxygen concentrations in the layers grown at lower temperatures. The electrical properties of the films were correlated with the intensity of the emission bands in the 410 to 440 nm and the 510 to 550 nm ranges observed in the 300 K photoluminescence spectra of the samples. The influence of impurities, native defects and threading dislocations on the film properties is discussed.