Thin films of CuCrO2 have been grown on Al2O 3(001) substrates by oxygen plasma assisted molecular beam epitaxy. With a substrate temperature of 700°C or 750°C, the films showed an unanticipated (015) orientation but at a higher substrate temperature of 800°C the expected basal (001) orientation predominates. The optical absorption spectrum of CuCrO2 shows a direct allowed absorption onset at 3.18eV together with a weak peak at 2.0eV which is suppressed by Sn doping. This suggests that the low energy peak should be attributed to 3d→3d excitations associated with Cu2+ defect states rather than excitations localised on Cr3+. Valence band X-ray photoemission spectra of (001) and (015) oriented CuCrO2 are compared with those obtained from polycrystalline samples.
Bibliographical noteFunding Information:
The Oxford MBE programme was supported by EPSRC Grant GR/S94148.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)