LAUSR

This paper examines the effects of lanthanum (La) loading on the structural, optical and electrical properties of tin monoxide (SnO) films as a p-type semiconducting layer. La loading up to 1.9 at% caused texturing of the tetragonal SnO phase with a preferential orientation of (101), which was accompanied by a smoother surface morphology. Simultaneously, the incorporated La cation suppressed the formation of n-type SnO2 in the La-doped SnO film and widened its optical bandgap. These changes allowed the 1.9 at% La-loaded SnO film to have higher hole mobility and carrier density compared to the La-free control SnO film. The superior semiconducting property was reflected in the p-type thin-film transistor (TFT). The control SnO TFTs exhibited field-effect mobility and ION/OFF ratio of 0.33 cm^2/Vs and 3.5 * 10^2, respectively. Enhancement of the mobilty value and ION/OFF ratio were observed for the TFTs with 1.9 at% La-loaded SnO channel layer, which was grown at the oxygen partial pressure of 4.5 %: they were improved to 1.0 cm^2/Vs and 2.4 * 10^4, respectively. The reason for this superior performance is discussed in terms of the smoother morphology, suppression of disproportionation conversion from Sn2+ to Sn0 + Sn4+, and reduced gap-state density.