Epitaxial properties of Al-doped ZnO thin films grown by pulsed laser deposition onSrTiO3(001)

Abstract

Undoped and Al-doped ZnO films with dopant concentrations of nominally 1% and 10% and a thickness of 100 nm have been grown on ${\mathrm{SrTiO}}_{3}(001)$ by pulsed laser deposition at substrate temperatures between 650 \ifmmode^\circ\else\textdegree\fi{}C and 820 \ifmmode^\circ\else\textdegree\fi{}C. The epitaxial conditions were examined with high pressure in-situ reflection high energy electron diffraction (RHEED) and ex-situ x-ray diffraction (XRD) measurements in different geometries. The films are highly $(11\overline{2}0)$-oriented with a lattice mismatch between the ${\mathrm{SrTiO}}_{3}[110]$ direction and the $c$-axis of about 3%. Atomic force microscopy (AFM) revealed smooth surfaces with a roughness of ${d}_{\mathit{rms}}<5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ and different sized islands.