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The instability of amorphous InGaZnO thin-film transistors is investigated under high drain current stress by applying bias voltages to both gate and drain electrodes. The instability involves positive threshold voltage shift, reduction of the ON-state current and recovery of the transfer characteristic toward the prestressed state when the stressed device is unbiased in dark at room temperature for an extended period. This instability behavior is investigated by low-frequency noise measurements before and after stress in the forward and reverse configurations. The overall results are consistent with the instability mechanism involving electron trapping in the existing donor-like gate oxide trap states near the source side.Index Terms-Amorphous IGZO (a-IGZO), donor-like traps, high-current stress, low-frequency noise, thin-film transistors (TFTs).

A fully analytical surface-potential-based drain current model for amorphous InGaZnO (α-IGZO) thin film transistors (TFTs) has been developed based on a Gaussian distribution of subgap states, with the central energy fixed at the conduction band edge, which is approximated by two exponential distributions. This model includes both drift and diffusion components to describe the drain current in all regions of operation. Using an empirical mobility relationship that depends on both horizontal and vertical electric field, it is demonstrated that the model describes accurately the experimental transfer and output characteristics, making the model suitable for the design of circuits using α-IGZO TFTs.

This study reports the effect of strain induced by bending on characteristics of a-IGZO TFTs fabricated on conformal aluminum substrates. The successful demonstration of IGZO TFTs on aluminum substrates presented in this study points to the promise of aluminum substrates for the use in future flexible display and electronics applications.

High performance thin film transistor (TFT) arrays and circuits on engineered aluminum substrates are reported. Aluminum substrates were engineered to have a smooth insulating surface suitable for device fabrication upon them. Amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors with an average field effect mobility of about 10 cm 2 /Vs, threshold voltage of 5 V, gate leakage current of 10 -13 and on/off current ratio of 10 8 are demonstrated. Metal oxide transistors and circuits built on aluminum substrates open a route for future applications in large area flexible electronics.