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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.

A 10.1 inch SVGA reflective type flexible active matrix electrophoretic displays were successfully fabricated on a thin metal foil substrate. It was developed a new multi‐barrier structure in order to use a rough metal foil as display substrate and designed a new TFT array structure for obtaining good performance. The backplane comprises a‐Si thin film transistor array fabricated using a conventional TFT manufacturing technologies. The 800×600 pixel display can be driven during extremely bending and measures only 0.3 mm in total thickness and weighs 32.8 grams. This prototype displays have a true paper‐like look and feel, with wide‐viewing angle and high contrast ratio.