Study Of Process And Properties Of ZnO Thin Films Grown By Pulsed Laser Deposition

With the fast developing information technology, wide band semiconductors attract much more attention because of the needs of short wavelength devices. ZnO is an II-VI compound wide-band-gap (3.37eV) semiconductor with a large exciton binding energy of 60 meV at room temperature. Theoretically, it can realize stimulated UV emission at RT, which makes it a promising material for using in ultraviolet light-emitting and laser diodes.There are many growth methods for ZnO films such as sputtering, vacuum vaporization, molecular beam epitaxy, pulsed laser deposition, chemical vapor deposition, atom layer epitaxy, spay pyrolysis, thermal oxidation and sol-gel. Pulsed laser deposition is a newly developed films growth technique which can fabricate high-quality films compared with other techniques, because of its advantage of simple hardware, atomic-layer control obtained by adjusting the laser energy density and repetition rate. In this technique, high density laser ablates the ZnO ceramic target and produces ZnO plume depositing on heated substrate in high vacuum background.In this paper, ZnO films were prepared on Si (111) substrates at various oxygen pressures, substrate temperatures and pulse energy, and then annealing was conduct. The films were examined by X-ray diffraction (XRD), scan electron microscopy (SEM), photoluminescence spectra (PL) and ellipsometry. Through the research of the structural and optical properties of ZnO films, effects of deposition parameters and optimized parameters for growing ZnO films were obtained. The results suggested that high quality ZnO films with highly c-axis oriented can be prepared by PLD.