Growth of c-oriented ZnO films on (0Â 0Â 1) SrTiO3 substrates by MOCVD

The growth direction of ZnO thin films grown by metal-organic chemical vapor deposition (MOCVD) is modulated by pretreatment of (0 0 1) SrTiO3 (STO) substrates. ZnO films show a-oriented smooth surface with epitaxial relationship of 〈001〉ZnO//〈110〉 STO on as-received STO, and c-axis columnar growth with 〈010〉ZnO//〈110〉 STO on etched STO, respectively. The orientation alteration of ZnO films is supposed to be caused by the change of STO surface polarity. In addition, the c-ZnO films exhibit an enhanced photoluminescence (PL) intensity due to the improved crystal quality, while the blueshift of PL peak is attributed to the smaller tensile strain. These results show that high quality c-ZnO, which is essential for electronic and optoelectronic device applications, can be grown on (0 0 1) STO by MOCVD.