Influence of dopant species and concentration on grain boundary scattering in degenerately doped In2O3 thin films

Abstract The influence of dopant species and concentration on the grain boundary scattering of differently doped In 2 O 3 thin films is studied by means of room temperature and temperature dependent Hall effect measurements. Barrier heights at grain boundaries E B are evaluated from temperature dependent carrier mobility taking the theoretically calculated temperature dependence of intragrain mobility into account. It is thereby shown that also samples with a negative temperature coefficient of mobility exhibit significant grain boundary barrier heights and that E B is usually underestimated when evaluated based on Seto's model. It is also shown that the most commonly used Sn doping of In 2 O 3 with a dopant concentration > 2 wt . % SnO 2 leads to significantly enhanced grain boundary scattering compared to nominally undoped, Zr-doped and H-doped films. An effect of grain boundary scattering is even observed for carrier concentrations ~ 10 21  cm − 3 if the films exhibit a pronounced (100) texture. The poor grain boundary properties of highly Sn-doped In 2 O 3 are attributed to segregation of the Sn dopants, which is also indicated by measurements of surface Sn concentration.