High-mobility nanometer-thick crystalline In–Sm–O thin-film transistors via aqueous solution processing

Abstract

Thin-film transistors (TFTs) based on solution-derived metal oxides hold great potential in emerging low-cost large-area printed electronics. Despite recent impressive progress, these device performances are far behind those of their corresponding vacuum-based counterparts, impeding their future commercialization. In this work, we designed and created high-performance TFTs based on a nanometer-thick (down to 5 nm) crystalline In–Sm–O channel via aqueous solution processing, with a performance comparable to those of existing vacuum-processed metal oxides. The microstructural, chemical, optical, and electrical properties of the ultra-thin In–Sm–O samples as a function of Sm doping content (0–10%) were comprehensively investigated. The In–Sm–O TFTs (5% Sm) on SiO₂/Si dielectrics demonstrated state-of-the-art performance, including a high mobility of 21.51 ± 1.33 cm² V⁻¹ s⁻¹, subthreshold swing of 0.66 ± 0.06 V per decade, threshold voltage of 2.14 ± 0.44 V, on/off current ratio >10⁸, and remarkable bias stress stability. The success of In–Sm–O was attributed to the high quality of the crystalline In₂O₃ matrix, the ideal nature of Sm dopant in suppressing oxygen vacancies, as well as the ultrathin and atomically smooth nature of the channel layer. Therefore, the aqueous solution-processed ultra-thin In–Sm–O channel is expected to enable the realization of future low-cost, large-area, and high-performance green electronics.