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.

Improved Performance and Operational Stability of Solution-Processed InGaSnO (IGTO) Thin Film Transistors by the Formation of Sn–O Complexes

“…In contrast, the aqueous fabrication technologies based on the solution process for AOSs have many advantages such as simplicity, large-area capability, low cost, and so on. The IGZO TFT, the most common AOS thin film, has been widely studied in the aqueous fabrication process and succeeds in low-temperature processes and low-voltage operation . In addition to IGZO, which is the most studied of the AOS thin films, the compositions of other AOS thin films such as ZTO and ITZO are also being studied, and improvements in electrical properties and instability are needed.…”

“…The IGZO TFT, the most common AOS thin film, has been widely studied in the aqueous fabrication process and succeeds in low-temperature 24 processes and low-voltage operation. 25 In addition to IGZO, which is the most studied of the AOS thin films, the compositions of other AOS thin films such as ZTO 26 and ITZO 27 are also being studied, and improvements in electrical properties and instability are needed. However, the solutionprocessed IGTO TFT has not been reported, and a study of the performance and stability of the solution-processed IGTO TFT is required for the next-generation TFTs.…”

Fully Printed High-Performance n-Type Metal Oxide Thin-Film Transistors Utilizing Coffee-Ring Effect

“…Here, on the contrary, we propose a novel printing approach that can take full advantage of such notorious "coffee-ring" effect to achieve high-performance indium tin oxide (ITO)-based TFTs and logic inverters. ITO has recently risen an excellent active channel material with highperformance mobility, beyond its conventional role as transparent conducting electrodes [30][31][32][33][34]. As a typical "coffeering" structure is featured with thin film in the center and thick ridges at the edge, in our approach, we directly integrated ITO TFTs from the coffee-ring structure as-printed (Fig.…”

“…1). The ultrathin ITO film (~10 nm in thickness) in the ring center can work as excellent semiconducting channel [31][32][33][34][35][36][37], while the thick ITO ridges can serve as parts of source/drain (S/D) electrodes. Benefited from the ultrathin nature of the ITO channels and the integrated design, our fully inject-printed ITO TFTs demonstrated a high optical transparency (~90%) and outstanding electrical property with a high saturation mobility (µ sat ) of 34.9 cm 2 V −1 s −1 , a low subthreshold swing (SS) of 105 mV dec −1 , a near-zero turn-on voltage (V on ) of −0.09 V, and a good current on/off ratio (I on/off ) of ~10 5 .…”

Effects of Channel Thickness on Electrical Performance and Stability of High-Performance InSnO Thin-Film Transistors

“…InSnO (ITO) is a kind of highly conductive material with a wide bandgap (3.5~4.3 eV) and high optical transmittance (~90%), which generally serves as transparent electrodes in electron devices [7][8][9]. High conductivity of the ITO films origins from a facile pathway for electron conduction that is introduced by a large overlap of 5 s orbits of In and Sn elements [10].…”