Structural characterization of nanocrystalline InN grown on porous silicon by reactive sputtering

In the present paper, we report results of indium nitride (InN) films grown at room temperature by reactive sputtering method on porous silicon (PS). The PS samples were prepared using photoelectrochemical (PEC) method on n-type silicon wafer with (111)-orientation. To fabricate porous structures, the samples were immersed into a mix-up of HF:Ethanol (1:1) with a current densities of 50 mA/cm(2) for 5 min, and subjected to external illumination from a 500 W ultraviolet (UV) lamp. The surface morphology and the crystalline structure of the InN films were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Structural analysis revealed nanocrystalline structure with crystallite size of 32 nm for these films. An entensive characterization of optical properties of InN layers were studied by Raman and Fourier transform infrared (FTIR) reflectance spectroscopy at room temperature (300 K). Raman result showed that A(1)(LO) (longitudinal optical phonons) of hexagonal InN has been observed at 588.4 cm(-1). From the result of FTIR spectroscopy, the TO [E-1(TO)] phonon mode of the InN is clearly visible at 472 cm(-1).