Modulating Electrical Performances of In₂O₃ Nanofiber Channel Thin Film Transistors via Sr Doping

Although In₂O₃ nanofibers (NFs) are considered as one of the fundamental building blocks for future electronics, the further development of these NFs devices is still seriously hindered by the large leakage current, low on/off current ratio (I_on/I_off), and large negative threshold voltage (V_TH) due to the excess carriers existed in the NFs. A simple one-step electrospinning process is employed here to effectively control the carrier concentration of In₂O₃ NFs by selectively doping strontium (Sr) element to improve their electrical device performance. The optimal devices (3.6 mol% Sr doping concentration) can yield the high field-effect mobility (μ_fe ≈ 3.67 cm² V⁻¹ s⁻¹), superior I_on/I_off ratio (≈10⁸), and operation in the energy-efficient enhancement-mode. High-κ Al₂O₃ thin films can also be employed as the gate dielectric to give the gate voltage greatly reduced by 10× (from 40 to 4 V) and the μ_fe substantially increased by 4.8× (to 17.2 cm² V⁻¹ s⁻¹). The electrospun E-mode Sr-In₂O₃ NF field-effect transistors (NFFETs) can as well be integrated into full swing of inverters with excellent performances, further elucidating the significant advance of this electrospinning technique toward practical applications for future low-cost, energy-efficient, large-scale, and high-performance electronics.