Oxygen partial pressure-dependent growth mechanism of low-dimensional zinc oxide on indium tin oxide glass

Abstract

The influence of O2 partial pressure on the growth mechanism of quasi-one-dimensional thermal-evaporated ZnO structure was explained by the preferential interface nucleation. At the relatively low temperature of 550 °C, the growth was governed by different growth mechanisms as the O2 partial pressure increased. At a very low O2 partial pressure of 0.3 Pa, the growth of ZnO nanowire on indium-tin oxide glass was Au-catalyzed vapor-liquid-solid (VLS) mechanism instead of vapor-solid (VS) mechanism. As increasing O2 partial pressure to 3 and 6 Pa, the ZnO needle-like structure was grown by self-catalyzed VLS mechanism. While, the VS mechanism was suggested for ZnO micropillar and two-dimensional ZnO sheet grown with the O2 partial pressure of 9 Pa and above. The near band edge (NBE) at 3.26 eV from the photoluminescence (PL) spectra strongly depended on the as-grown structure. In addition, PL at 2.32 eV corresponded to the ZnO defects due to the oxygen vacancies within 14 nm beneath the one-dimensional ZnO surface.