InN layers grown on silicon substrates: effect of substrate temperature and buffer layers

This work reports on the effect of the substrate temperature and buffer layers on wurtzite InN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) on Si(1 1 1) substrates. Growth temperature is found to be the most critical parameter during the growth of InN layers. Growths performed above 500 °C lead to the formation of metallic indium droplets on the surface. Once the temperature has been fixed below 500 °C, the morphology can be controlled by the effective indium to nitrogen molecular flux ratio, from N-rich conditions that lead to columnar InN layers, to stoichiometric conditions leading to coalesced InN films. The effect of different types of buffer layers has also been investigated determining the crystal quality of the samples. X-ray diffraction (XRD) rocking curves around the InN (0 0 0 2) reflection yield a minimum full-width at half-maximum (FWHM) value of 682 arcsec for a compact InN layer grown on a high-temperature AlN buffer layer.