ZnO films were deposited on c-Al2O3 using pulsed laser deposition both with and without N2 in the growth ambient. X-ray diffraction revealed poorer crystal quality and surface morphology for one-step growths with N2 in the ambient. A marked improvement in both the crystallographic and surface quality was obtained through use of two-step growths employing nominally undoped ZnO buffer layers prior to growth with N2 in the ambient. All films showed majority n-type conduction in Hall measurements. Post-annealing for 30 minutes at 600 °C in O2 systematically reduced both the carrier concentration and the conductivity. A base room temperature carrier concentration of ~ 1016 cm -3 was linked to Al diffusing from the substrate. 4.2 K photoluminescence spectra exhibited blue bands associated with the growths having N2 in the ambient. Temperature dependent Hall measurements were consistent with N being incorporated in the films. Processed devices did not, however, show rectifying behaviour or electroluminescence. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
|Number of pages||4|
|Journal||Physica Status Solidi C - Current Topics in Solid State Physics|
|Publication status||Published - 2008|
|Event||34th International Symposium on Compound Semiconductors - Kyoto, Japan|
Duration: 15 Oct 2007 → 18 Oct 2007