Comparison of ZnO:GaN films on Si(1 1 1) and Si(1 0 0) substrates by pulsed laser deposition

Abstract

We report the growth of undoped and GaN-doped ZnO films on Si(1 1 1) and Si(1 0 0) substrates by pulsed laser deposition (PLD). The undoped ZnO films were doped with N and Ga by means of a codoping process using GaN. The effect of N concentration and the lattice mismatch have been investigated. The X-ray diffraction (XRD) full-width at half-maximum (FWHM) of the films decreases with increasing the N concentration up to 0.8%. However, after that it begins to increase. Photoluminescence (PL) spectra exhibit deep level emissions with a very low intensity in the GaN-doped samples, revealing their good optical quality. Although the glow discharge mass spectra (GDMS) confirm the presence of N in the films, the results of Hall measurements show that they exhibit n-type conductivity. Our results indicate that the films grown on Si(1 0 0) reveal better structural, electrical and optical properties rather than on Si(1 1 1) due to the lower lattice mismatch between Si(1 0 0) substrate and ZnO film.