Growth of InN nanocrystalline films by activated reactive evaporation

InN films are grown on silicon and glass substrates by radio frequency (rf) activated reactive evaporation. High purity indium (99.99) is evaporated by resistive heating in the presence of nitrogen plasma. X-ray diffraction shows that the film deposited at low rf plasma powers (< or =100 W) are indium rich and further increase in the rf power formation of InN take place. The average crystallite size was found varying from 8 nm to 20 nm as the power increases from 200 to 400 W. The diffraction pattern shows the polycrystalline nature of InN films. The band gap obtained from the transmission spectra show an increase in the band gap with the increase in rf power which can be attributed to variation of nitrogen: indium stoichiometry. The Raman spectra shows wurtzite nature of the film and the photoluminescence measurements show a weak peak around 1.81 eV for the film grown at 400 W. Plasma diagnostics has been carried out in order to understand the role of active species in the process. The large shift in the band gap is attributed to Moss-Burstein shift and presence of residual oxygen in the film.