|
Wurtzite-type Indium nitride (InN) films have been prepared directly on the c-plane sapphire substrate by a self-designed radio-frequency plasma metal organic molecular beam epitaxy (RF-MOMBE) system. In this paper, mirror-like AlN was used as a buffer layer for the growth of InN films on sapphire substrate and the effect of growth characteristics of InN was investigated. We have investigated the influence of InN films on the surface morphology and crystal structures by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). Electrical and optical properties were performed by Hall Effect system and photoluminescence (PL) measurements. The result indication InN films preferentially c-axis oriented. The surface morphology of the InN film was quite smooth for mirror-like AlN buffer layer. The surface roughness was obtained from SEM measurements with increased growth temperature. Also, the PL peaks show a blue shift from 1.35 eV to 1.64 eV at difference N2 plasma powers. Furthermore, a pronounced two-dimensional growth mode was observed at the growth temperature of 500 oC, and this film shows highly orientation along the c-plane. These results indicate that the control of growth temperature and RF power are essential for engineering the growth of InN on Al2O3 (0001), and it might be also applicable for other lattice-mismatched III-V heteroepitaxial systems. |