Epitaxial growth of ZnO thin films on LiGaO2 substrates by pulsed-laser deposition

Lattice-matched (Δa/a=1.8–3.4%) (0 0 1) LiGaO2 substrates have been employed for the first time to grow ZnO thin films by pulsed-laser deposition at 350–650 °C with oxygen partial pressure of 20 Pa. XRD shows that a highly c-axis-oriented ZnO film can be deposited on (0 0 1) LiGaO2 substrate at 500 °C. AFM images reveal the surfaces of as-deposited ZnO films are smooth and root-mean-square values are 6.662, 5.765 and 6.834 nm at 350, 500 and 650 °C, respectively. PL spectra indicate only near-band-edge UV emission appears in the curve of ZnO film deposited at 500 °C. The deep-level emission of ZnO film deposited at 650 °C probably results from Li diffusion into the film. All the results illustrate substrate temperature plays a pretty important role in obtaining ZnO film with a high quality on LiGaO2 substrate by pulsed-laser deposition.