Micro-Textured Milky ZnO:Ga Thin Films Fabricated by Pulsed Laser Deposition Using Second-Harmonic-Generation of Nd:YAG Laser

Abstract

Approximately 800-nm-thick ZnO films doped with 4 wt% Ga₂O₃ (GZO films) have been deposited on glass and quartz substrates by a pulsed laser deposition method using Second-Harmonic-Genreation (SHG) of Nd:YAG laser (λ=532 nm). In all experiments, a repetition rate of 10 Hz, energy densities of 0.1–2.5 J/cm², and irradiation times of 2–3 h were used. Scanning Electron Microscopy (SEM) observations of the film surface revealed that there were micro-textured structures (0.5–1 µm in diameter), surrounded by small rugged and irregular structures (250–400 nm in size). It was recognized from XRD spectra that a strong peak of (103) planes reflected from the micro-textured milky surfaces is dominant. A haze ratio of 46.6 % was obtained at a wavelength of 550 nm for approximately 800-nm-thick GZO (4 wt%) films grown at a substrate temperature of 300 °C in oxygen with a flow rate of 3 sccm. The lowest resistivity of 2.33×10^-4 Ω·cm and the lowest sheet resistance of 2.72 Ω/sq were obtained for these GZO (4 wt%) films.