Solution-processed ITO thin-film transistors with doping of gallium oxide show high on-off ratios and work at 1 mV drain voltage

Abstract

Indium tin oxide (ITO) is generally used as an electrode material but has recently been demonstrated to be a competitive candidate for use in semiconductor layers in high-performance thin-film transistors (TFTs), due to its high mobility and strong resistance to wet-etching. Here, we demonstrate TFTs using solution-processed, ultra-thin ITO films with outstanding switching performance. These devices exhibit a mobility of up to 15 cm2 V−1 s−1 and a high on-off ratio of 108. Because the device exhibits significant instability under stress tests, moderate doping with Ga as a dopant is introduced to form Ga-doped ITO TFTs. The resulting device has much enhanced stability, near-zero turn-on voltage, and a high on-off current ratio of 108. Through further involvement of an AlOx dielectric layer, the Ga-doped ITO TFTs exhibit a high apparent mobility of more than 40 cm2 V−1 s−1 and operate at small gate voltages (3 V). Remarkably, the device maintains an on-off ratio of over 104 at drain voltages as small as 1 mV.