Determination of the surface reactivity of growth species in the AP-MOCVD of ZnO from DEZ and H2O and thermal analysis of the “captured” intermediate species

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 H2O 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, ks, 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.