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

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 cosputter deposition of Ga-doped ZnO and SnO(2). 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 NiOx 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. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim