Epitaxial growth of Al-doped ZnO thin films grown by pulsed laser deposition

Epitaxial thin films of aluminum-doped zinc oxide (AZO) have been deposited on single crystal sapphire (000l) substrates by pulsed laser deposition. The structural, electrical and optical properties of these films were investigated as a function of substrate deposition temperature and background gas pressure. Films were deposited at substrate temperatures ranging from 25 to 680 °C in oxygen pressures ranging from 0.13 to 9.31 Pa. For the 200-nm-thick single crystal AZO film, the electrical resistivity was observed to be 2.2×10−4 Ω·cm and the average transmission in the visible range (400–700 nm) was 90%. This low resistivity value for the single crystal AZO film is due to the high carrier mobility of the film, which results from a decrease in the grain boundary scattering, compared to polycrystalline AZO films.