Threshold voltage control by gate electrode in Ga–Sn–Zn–O thin‐film transistors for logic inverter application

Abstract We report on the fabrication of Ga–Sn–Zn–O thin‐film transistors (GTZO‐TFTs) and their inverter application. For the most stable and highly‐performing GTZO‐TFT, an optimal oxygen pressure condition was extracted out during co‐sputter deposition of Ga‐doped ZnO and SnO₂. Using the oxygen pressure condition, we fabricated top‐gate GTZO‐TFTs for a logic inverter, which has two serially‐connected top‐gate TFTs with different gate electrodes: conducting NiO_x and Al. Since the electrodes have very different work functions controlling the threshold voltages of TFTs, our inverter demonstrated a nice operation at less than 5 V with a high voltage gain of over 25. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)