Electrical Characterization and Modeling of Amorphous ITO Field-effect Transistors

This work systematically investigates the electrical properties and device physics in short-channel indium tin oxide (ITO) field-effect transistors (FETs). A $\mathbf{150-nm-channel-length}$ device was fabricated using semiconducting ITO as the active channel layer. The fabricated transistors demonstrated normally-off operation with a threshold voltage of 0.1 V at $100 \mathrm{pA} * \mathrm{~W} / \mathrm{L}$ standard, a subthreshold swing of $68 \mathrm{mV} /$ dec, a transconductance of $223 \mu \mathrm{~S} / \mu \mathrm{m}$ at $\mathrm{V}_{\mathrm{ds}}=0.5 \mathrm{~V}$, and a high on-state current of 602 $\mu \mathrm{A} / \mu \mathrm{m}$ at $\mathrm{V}_{\mathrm{ds}}=1 \mathrm{~V}$. Furthermore, a physical device model incorporating actual process parameters was developed using the SILVACO TCAD platform. High-fidelity matching of the transfer and output characteristics with experimental data was achieved by establishing a density of states model specific to amorphous oxide semiconductors. Positive and negative bias stress tests were conducted to evaluate the reliability degradation under bias stress and to analyze the threshold voltage shift mechanisms. The results indicate that electron trapping at the insulator/channel interface is the dominant factor contributing to the negative threshold voltage drift. This work provides a theoretical foundation for optimizing the device performance and reliability mechanisms in amorphous oxide transistors, offering critical insights for advancing high-performance oxide semiconductor electronics.