Effect of surface roughness on electrical characteristics in amorphous InGaZnO thin-film transistors with high-κ Sm2O3 dielectrics Original Research Article

We investigated the effect of surface roughness on the electrical characteristics in amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) fabricating high-κ Sm2O3 gate dielectrics, prepared under different annealing temperatures. The high-κ Sm2O3 a-IGZO TFT device annealed at 200 °C exhibited better electrical characteristics, including a large field effect mobility of 6.25 cm2/V s, small threshold voltage of 0.79 V, low subthreshold swing of 354 mV/decade, and high Ion/Ioff ratio of 3.1×107. These results are attributed to the formation of smooth surface at the oxide/channel interface. Furthermore, the reliability of a Sm2O3 a-IGZO TFT device can be improved by oxygen annealing at low temperature.