Homoepitaxial ZnO thin films by PLD: Structural properties

Homoepitaxial ZnO films deposited on annealed hydrothermal O‐face ZnO single crystals show superior structural quality. This is demonstrated by narrow ZnO(00.2) rocking curves with FWHM of typically 23 to 35 arcsec, and nearly dislocation‐free TEM cross sections. Nominally undoped ZnO films indicate a minor in‐plane strain of about 250 ppm and no out‐of‐plane strain. Target doping by 0.01% P2O5 or 0.5% Li3N results in pseudomorphic film growth without in‐plane strain. Increasing doping concentration of 0.1 and 1% P2O5 results in both in‐plane and out‐of‐plane strain up to 0.9% indicating relaxed films. The O‐face polarity of the homoepitaxial ZnO films is confirmed by convergent beam electron diffraction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)