Enhancement of Gas Response of ZnO Micro-nano Structured Films through O₂ Plasma Treatment

Abstract

Layers of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O₂ and N₂. It was found that exposure to O₂ plasma enhanced gas response to ethanol vapor of the ZnO layers by a factor eight, while exposure to N₂ plasma deteriorated the gas response. The gas response enhancement upon O₂ plasma treatment could be correlated to an increase in the layer resistance combined with surface roughening of the original ZnO tetrapod structure, suggesting the formation of a ZnO surface with a high density of active sites for ambient oxygen adsorption and subsequent reaction with reducing gases such as ethanol vapor.