Polarity Determination of Polarity-Controlled ZnO Films Using Photoresponse Characteristics

Abstract

We report on the use of the photoresponse characteristics of polaritycontrolledZnO films for determining ZnO polarity. ZnO films were grown onCrN and Cr2O3 buffer layers in order to produce Zn- and O-polar films,respectively, and Ti/Au metal contacts were formed. All samples showed Ohmicbehavior, but the Zn-polar ZnO film showed lower contact resistance thanthe O-polar ZnO film. The O-polar ZnO film showed higher photocurrent andlonger decay time than the Zn-polar film by photoresponse measurement.These phenomena can be explained by the expansion of the depletion layerinto the bulk ZnO surface. Compared with current methods, this method ofdetermination of the polarity of ZnO films through the measurement of photoresponse characteristics is very easy and simple to implement.