Some Properties of Group-III Nitride Thin Films Directly Grown on Non-Single-Crystalline Substrates by Using a Molecular Beam Epitaxy Apparatus

Gallium nitride (GaN) and indium-gallium nitride (InxGa1-xN) thin films were directly grown on several non-single-crystalline substrates such as quartz glass and amorphous-carbon-coated graphite. The films were grown by using a molecular beam epitaxy apparatus having single or dual nitrogen radio-frequency plasma cells, and in addition, germanium (Ge) or magnesium (Mg) doping to the films was also attempted. Crystallinity, photoluminescence (PL) property, and electrical property of the obtained films were investigated. Highly c-axis oriented GaN and InxGa1-xN thin films were obtained on the non-single-crystalline substrates. Near-band-edge emissions were observed in their PL spectra and the intensities were strongly enhanced by Ge doping. Ge doping was also effective on reducing resistivity of the GaN thin films grown on the non-single-crystalline substrates. Electrochemical capacitance-voltage measurements were carried out on the Mg-doped GaN thin films; and p-type conduction in the films was confirmed.