Structural and optical characterization of PA-MOCVD grown ZnO nanorod-arrays on silicon substrates

In this study, vertically well-aligned ZnO nanorod arrays were successfully grown on silicon wafers at a low temperature of 400 degrees C by using a catalyst-free plasma-assist metalorganic chemical vapor deposition (PA-MOCVD) technique. The detailed investigation on the optical and the structural properties of the as-grown ZnO nanorods was performed by using various analytical techniques. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) investigations indicated that the ZnO nanorods grown at inductively coupled plasma (ICP) powers above 150 Watt were highly c-axis aligned with a high crystal quality as demonstrated by the ZnO (0002) rocking curve being as narrow as 3.41 degrees. Photoluminescence (PL) at room temperature (RT) and 6 K clearly confirmed that the ZnO nanorods in the present study had excellent optical quality and high purity, showing only free exciton emission peaks at 3.383 eV and 3.30 eV in the 6 K and the RT PL spectra, respectively, without any trace of defect related emissions.