Halide vapor phase epitaxy of ZnO studied by thermodynamic analysis and growth experiments

Thermodynamic analyses of halide vapor phase epitaxy (HVPE) for the growth of ZnO were conducted to investigate the effects of growth conditions against growth rates. The partial pressures of gaseous species in equilibrium with ZnO and the resultant driving force for ZnO deposition are calculated with respect to temperatures, input H2 pressures and input VI/II ratios. It has been revealed that the driving force is weakly dependent on the temperature and is still positive even at 1200 °C, while it greatly decreases at higher temperatures in the presence of H2. The driving force is also significantly influenced when the VI/II ratio is below 1000. The experimental growth rates substantially agree with the dispositions of the driving force expected from the thermodynamic analyses.