Properties of ZnO(0001) layers grown by metalorganic chemical vapor deposition on GaN(0001) templates

Abstract

We studied the properties of ZnO(0001) layers grown by metalorganic chemical vapor deposition on GaN(0001) templates. A two‐step growth procedure was used where a buffer layer was first deposited at 400 °C before the temperature was increased to 900 °C for the deposition of the epitaxial layer. Atomic force microscopy revealed locally straight steps on a 20 × 20 mm2 scan area. This indicates a step‐flow growth mode. The root‐mean‐square roughness was 2.6 nm. The surface exhibited hexagonal pits. The pit density was 7.5 × 105–2.1 × 108 cm–2. The full width at half maximums of w‐scans for the symmetric (0002) and the skew‐symmetric (20$ \bar 2 $1) reflections were 0.091° and 0.159°, respectively. The ZnO films were fully relaxed as revealed by reciprocal space maps for the (10$ \bar 1 $5) reflection. Gallium doped n‐type ZnO layers were deposited on (In,Ga)N light emitting diodes as transparent contacts. The electron concentration was 9.4 × 1019 cm–3 and the sheet resistance 45 W/sq. The resistivity and the mobility was 1.5 × 10–3 Wcm and 43 cm2/(Vs), respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)