Channel scaling and field-effect mobility extraction in amorphous InZnO thin film transistors

Amorphous oxide semiconductors (AOSs) based on indium oxides are of great interest for next generation ultra-high definition displays that require much smaller pixel driving elements. We describe the scaling behavior in amorphous InZnO thin film transistors (TFTs) with a significant decrease in the extracted field-effect mobility mu(FE) with channel length L (from 39.3 to 9.9 cm(2)/V.s as L is reduced from 50 to 5 mu m). Transmission line model measurements reveal that channel scaling leads to a significant mu(FE) underestimation due to contact resistance (RC) at the metallization/channel interface. Therefore, we suggest a method of extracting correct lFE when the TFT performance is significantly affected by R-C. The corrected mu(FE) values are higher (45.4 cm(2)/V.s) and nearly independent of L. The results show the critical effect of contact resistance on mu(FE) measurements and suggest strategies to determine accurate mu(FE) when a TFT channel is scaled. (C) 2017 Elsevier Ltd. All rights reserved.