Scanning tunneling microscopy study of the surface electrical properties of ZnO films grown by pulsed laser deposition

Abstract

Highly (001) textured ZnO films grown on (100)InP by pulsed laser deposition have been studied by Scanning Tunneling Microscopy (STM). Constant current images show a well defined grain structure, which allows to perform local spectroscopic studies. From differential conductance spectra an asymmetry of the electrical properties at both sides of the boundaries can be observed, which can be attributed to the formation of space charge layers. On the other hand the electrical behavior, in particular the conduction type, differs from grain to grain, likely due to the different orientation of the faces exposed to the STM tip.