Determination of the surface reactivity of growth species in the AP-MOCVD of ZnO from DEZ and H 2O and thermal analysis of the “captured” intermediate species

Abstract

In this study, ZnO films were deposited on silicon wafers patterned with micron-sized trenches in a flow type MOCVD reactor using DEZ- n-hexane and H 2O as precursors. Scanning electron microscopy was used to measure the film thickness within the micro-trench. Using a modified model equation to fit the experimental growth rate data, we were able to determine the surface reaction rate constants, k s, or the sticking coefficients, η. At temperatures from 400 to 500 °C, η from 0.5 to 0.6 was obtained. Interestingly, η was decreased to 0.2 at higher temperatures of 700–750 °C. In order to verify if different growth species are present at low temperature of 400 °C and high temperature of 700 °C we employ a novel method to “capture” the intermediate species. Thermal analysis of the sample obtained at the reaction temperature of 400 °C revealed two endothermic peaks at 79 and 114 °C, while the sample obtained at 700 °C revealed three peaks at 84, 117 and 142 °C.