HETEROEPITAXIAL GROWTH OF CUBIC GAN ON GAAS BY GAS-SOURCE MOLECULAR-BEAM EPITAXY

GaAs and GaN were grown epitaxially on GaAs substrates by gas-source molecular beam epitaxy using diethylarsine (DEAs) and dimethylhydrazine (DMHy) as As and N sources, respectively. It was found that cubic GaN grows on nitrided GaAs(001) surfaces, in contrast with the growth of hexagonal GaN on GaAs(111) surfaces. Cathodoluminescence spectra suggest that cubic GaN has about a 0.4 eV larger band gap energy than that of the hexagonal one. It was also found that GaAs preferentially grows to GaN when DEAs and DMHy beams are supplied with a Ga beam onto the substrates simultaneously. Thus, only by intermittent supply of a DEAs beam, GaN/GaAs multilayers were obtained.