Enhanced Carrier Generation in Nb-Doped SnO2 Thin Films Grown on Strain-Inducing Substrates

We report the effect of lattice strain from the substrate on carrier generation in Nb-doped SnO2 (NTO) transparent conductive oxide (TCO) thin films. The carrier activation efficiency of Nb was strongly affected by in-plane tensile strain, and the NTO films grown on c-Al2O3 and anatase TiO2 seed layers had carrier density (n(e)) as high as 3 x 10(20) cm(-3). In contrast, strain-free NTO films grown on glass exhibited much smaller n(e) due to the formation of deep impurity levels. These results imply that NTO has potential as a practical TCO in the presence of substrate-film epitaxial interaction. (C) 2012 The Japan Society of Applied Physics