Deposition-temperature dependence of ZnO/Si grown by pulsed laser deposition

We have investigated structural and optical properties of ZnO films deposited on (100) Si substrates at various deposition temperatures by pulsed laser deposition. All the ZnO films show columnar structure due to the growth behavior of ZnO; the (0001) plane has the fastest growth rate, but on increasing the deposition temperature the film texture varies from c-axis orientation normal to substrate surface to random orientation. This tendency can be explained by the negative activation energy evaluated from growth rate as a function of inverse deposition temperature, which implies that ZnO films are grown in a, surface-kinetics-limited regime. FWHM of the UV-emission peak does not change at various deposition temperatures, and its mean value is about 115 meV. In contrast to FWHM, the intensity of UV emission drastically increases with increasing deposition temperature, due to the reduction of grain-boundary recombination effect.