Investigation on electrical properties of indium tin oxide thin films by effective control of crystallographic orientation

Abstract

Although indium tin oxide (ITO) film has been widely used in optoelectronic devices, it remains difficult to systemically determine the structural properties' influence on electrical properties for ITO. In this work, ITO films are grown by metal organic chemical vapor deposition (MOCVD). By introducing nucleation layers, the structural properties could be controlled effectively so that the dependence of electrical properties on crystallographic orientation and O2 partial pressure could be investigated separately. It is found that (1) for the samples grown with the same doping level, the decrease in carrier concentration with increasing oxygen flow rate is purely attributed to the increasing O2 partial pressure rather than different crystallographic orientation; (2) electron mobility of the ITO films is strongly affected by crystallographic orientation and it decreases with (100)-grain density. Analysis by using carrier's transport theory reveals that the averaged barrier height of grain boundary scattering increases with the (100)-grain density.