Invited Paper TF1-FrM3
Fabrication and Characterization of Indium Zinc Oxide-Based Thin Film Transistors

Friday, October 19, 2007, 8:40 am, Room 602/603

Active electronics implemented on cheap flexible polymer substrates offer the promise of novel display technologies, wearable electronics, large area memory, and a multitude of other, as-yet-unthought-of, applications that require low cost and high volume manufacturing. Thin film transistors (TFT’s) fabricated on temperature-sensitive plastic substrates at low temperatures are the key to this technology. TFT’s that use metal (In, Zn, Sn, Ga) oxide channels offer both high mobility (relative to amorphous Si) and the advantage of optical transparency in the visible regime. We report on the fabrication and performance of amorphous oxide transparent thin film transistors that use dc-magnetron sputter techniques to deposit IZO (In2O3-10wt%ZnO) at low oxygen potential (0vol%O2) for the source, drain, and gate-contact metallization and, at higher oxygen partial pressures (10 vol%O2), for the semi-conducting channel. The devices in this study were processed at room temperature except for a single 280°C PECVD deposition step to deposit a 230 nm-thick SiOx gate dielectric. The devices are optically transparent and operate in depletion mode with a threshold voltage of -5 V, mobility of 15 cm2/Vsec, an on-off ratio of >10E6 and, a sub-threshold slope of 1.2 V/decade. We show that control of oxygen in the sputter gas (0 to 30 vol %) during IZO deposition allows control of carrier density.