01697nas a2200205   4500008004100000245008500041210006900126300000800195490000800203520102000211100001901231700003101250700002101281700002501302700002301327700002301350700002101373700002101394856007601415       1996                        eng d00aImpact of Growth Temperature, Pressure and Strain on the Morphology of GaN Films0 aImpact of Growth Temperature Pressure and Strain on the Morpholo  a2270 v4493 a<p>GaN films grown on sapphire at different temperatures are investigated. A Volmer-Weber growth mode is observed at temperatures below 1000K that leads to thin films composed of oriented grains with finite size. Their size is temperature dependent and can actively be influenced by strain. Largest grains are observed in compressed films. It is argued that diffusing Ga ad-atoms dominate the observed effects with an activation energy of 2.3 ± 0.5 eV. Comparably large grain sizes are observed in films grown on off-axes sapphire substrates and on bulk GaN. This assures that the observed size limitation is a consequence of the 3D growth mode and not dependent on the choice of the substrate. In addition, the grain size and the surface roughness of the films depend on the nitrogen partial pressure in the molecular beam epitaxy (MBE) chamber,most likely due to collisions between the reactive species and the background gas molecules. This effect is utilized to grow improved nucleation layers on sapphire.</p>1 aFujii, Hiroaki1 aKisielowski, Christian, F.1 aKrüger, Joachim1 aLeung, Michael, S.H.1 aKlockenbrink, Ralf1 aRubin, Michael, D.1 aWeber, Eicke, R.1 aKrüger, Joachim  uhttps://facades.lbl.gov/publications/impact-growth-temperature-pressure