Molecular beam epitaxial growth of ZnCrO films by using RF plasma source

The transition‐metal chromium‐doped zinc oxide, ZnCrO, was successfully grown on an a ‐sapphire (11$ \bar 2 $0) substrate by radio frequency‐plasma‐assisted molecular beam epitaxy. The growth and optical property of ZnCrO were investigated. The growth mode changed from a 2‐dimensional one to a 3‐dimensional one with Cr doping. The ZnCrO films showed a textured morphology and the surface roughness of each was clearly reduced by increasing the amount of Cr doping. The X‐ray diffraction peak intensity from ZnO (0002) became smaller as the Cr cell temperature was increased. A photoluminescence spectrum of ZnCrO was dominated by an excitonic peak around 3.36 eV. The transmission spectra showed that light wavelength shorter than 3.26 eV was removed. This was caused by Cr doping, and its losses caused by Cr doping. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)