TY - Generic T1 - Impact of Growth Temperature, Pressure and Strain on the Morphology of GaN Films T2 - Materials Research Society Symposium N – III-V Nitrides Y1 - 1996/ SP - 227 A1 - Hiroaki Fujii A1 - Christian F. Kisielowski A1 - Joachim Krüger A1 - Michael S.H. Leung A1 - Ralf Klockenbrink A1 - Michael D. Rubin A1 - Eicke R. Weber ED - Joachim Krüger AB - 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. JF - Materials Research Society Symposium N – III-V Nitrides VL - 449 U1 -

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U2 - LBNL-39850 DO - 10.1557/PROC-449-227 ER -