Voltage-driven gated van der Pauw method for accurate channel and contact resistance extraction in oxide Thin-Film Transistors

Abstract

Precise characterization of both channel and contact characteristics in p- and n-type oxide thin-film transistors (TFTs) is essential for the development of next-generation low-power complementary metal–oxide–semiconductor circuits. However, p-type oxide TFTs remain limited by inherently low hole concentrations and inefficient charge injections at the contacts, leading to high contact resistance and performance limitation. To address these challenges, a voltage-driven gated van der Pauw (V-gVDP) method is proposed, enabling the simultaneous and accurate extraction of the channel sheet conductance (${\sigma }_S$) and the specific contact resistivity (${\rho }_C$) compared to the conventional current-driven gVDP or the transmission line method (TLM). Voltage differences in the V-gVDP enable spatial decoupling and independent evaluation of channel and contact characteristics using a single device, without the need for control devices, with superior precision and reproducibility. The relative standard deviation (RSD) of the extracted sheet resistance (R_S) from the V-gVDP was reduced by factors of 6 and 46 for SnO and IGZO, respectively, while the RSD of ${\rho }_C$ was improved by factors of 51 and 10 compared to the TLM. The V-gVDP method was successfully applied to both p-type SnO and n-type IGZO TFTs, confirming its robustness and versatility across different carrier polarities. These results demonstrate the potential of the V-gVDP method as a reliable and high-precision platform for characterizing oxide semiconductors and optimizing CMOS circuits and contact engineering.