Corona Discharge Assisted Growth Morphology Switching of Tin-Doped Gallium Oxide for Optical Gas Sensing Applications

摘要

To match the properties of a semiconductor to a desired application, it is crucial to control its crystal structure. Here, we show that, by implementing a corona discharge in a chemical vapor deposition process, the growth morphology of gallium oxide can be adjusted to produce nanowires and layerlike and columnar crystal structures. The three morphologies can be explained by the transition from a classic chemical vapor process to a corona-assisted chemical vapor process with directed transport. Specifically, the excitation of the carrier gas by the corona discharge is exploited as a switch to transition from a vapor-liquid-solid nanowire growth mechanism to a layer by layer growth mechanism. The second switching parameter is the substrate bias which affects the directed precursor transport and enhances the growth rate. While the switching of the morphology has no effect on the crystal phase, the photoluminescence properties of the three morphologies are different. The grown structures are used as optical gas sensors at room temperature. Tin-doped gallium oxide is shown to be capable of detecting trace amounts (200 ppm) of alcohols such as acetone, ethanol, and isopropanol. The layerlike morphology provides the highest response.