• Morrod, J.
• Demazeau, Gérard
• Hassani, S.
• Rogers, D. J.
• Prior, K. A.
• Teherani, F. Hosseini
• Look, D. C.
• Minder, K.
• Largeteau, Alain
• Razeghi, M.
• Lusson, Alain

Abstract

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 ºC 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.

Topics

• surface
• photoluminescence
• x-ray diffraction
• thin film
• annealing
• pulsed laser deposition