Impact of Precursor Solvent Chemistry on Electrical Properties of Indium Oxide Films for Thin-Film Transistors

Indium oxide In_2O_3 combines high carrier mobility with optical transparency, making it a promising candidate for next-generation thin-film electronics. However, its electrical performance is highly sensitive to fabrication parameters, particularly the chemistry of solution-based precursors, which can alter defect landscapes and carrier transport mechanisms. This work systematically examines how solvent choice influences the structural and electronic properties of solution-processed In_2O_3 thin films, isolating processing–property relationships that remain insufficiently understood. Films prepared from water and 2-methoxyethanol (2ME) precursors were characterized using temperature-dependent transmission line method (TLM) measurements from 30~K to 300~K. Water-processed films exhibited consistently lower sheet resistance, a reduced activation energy (2.0~meV vs.\ 12~meV for 2ME), and a significantly lower hopping parameter T_0, indicating reduced spatial and energetic disorder. AFM revealed smoother surface morphology for the water-based films, while XPS showed a higher oxygen vacancy-to-lattice oxygen ratio, consistent with enhanced carrier density. These results demonstrate that solvent identity can be used to tune both functional and structural disorder, enabling substantial improvements in charge transport without doping or high-temperature processing. This solvent-driven approach provides a viable pathway for engineering high-performance, low-temperature oxide semiconductors for applications such as radiation-tolerant and flexible electronics.