Sudheer Kumar

Study of iron-catalysed growth of ?-Ga2O3 nanowires and their detailed characterization using TEM, Raman and cathodoluminescence techniques

In this paper, we demonstrate a new catalyst (Fe) to grow single crystalline beta-gallium oxide (?-Ga2O3) nanowires (NWs) via the vapour?liquid?solid mechanism using the chemical vapour deposition technique. The structural studies of these NWs showed the highly crystalline monoclinic phase of Ga2O3. This was confirmed by detailed scanning transmission electron microscope investigations demonstrating the NW to be single crystalline ?-Ga2O3, growing along the normal of the plane. We also compared Raman and cathodoluminescence (CL) properties of the as-grown ?-Ga2O3 NWs with a bulk Ga2O3 single crystal grown by the Czochralski method. It was observed that Raman peak positions of a single ?-Ga2O3 NW had a red frequency shift of about 0.3?1.4?cm?1 as compared to a bulk Ga2O3 single crystal, which was in fact quite small. In addition, the CL measurements of ?-Ga2O3 NWs and the bulk Ga2O3 single crystal exhibited similar spectra, having a strong broad UV?blue emission band and a weak red emission band. Moreover, the structural, morphological and optical properties of Fe-catalysed ?-Ga2O3 NWs were comparable to those of Au-catalysed ?-Ga2O3 NWs.

Study of high quality spinel zinc gallate nanowires grown using CVD and ALD techniques

High quality single crystalline zinc gallate (ZnGa2O4) nanowires (NWs) were grown using a combination of chemical vapor deposition and atomic layer deposition techniques. Morphological, structural and optical investigations revealed the formation of Ga2O3-ZnO core-shell NWs and their conversion into ZnGa2O4 NWs after annealing via a solid state reaction. This material conversion was systematically confirmed for single NWs by various measurement techniques including scanning and transmission electron microscopy, Raman spectroscopy and voltage-dependent cathodoluminescence. Moreover, a model system based on the obtained results has been provided explaining the formation mechanism of the ZnGa2O4 NWs.