Using the low temperature poly‐Si technology, the 3.5‐inch diagonal QVGA320* RGB*240 TFT‐LCD with integrated circuits was developed for handheld applications. We integrated 6 bit digital data driver with ramp‐type digital‐analogue converter and gate driver that can operate bi‐directionally. The characteristics of the poly‐Si TFT used to integrate driver circuits are followings; 1 in NMOS, Vth∼2V and mobility∼200cm2/Vsec, 2 in PMOS, Vth ∼ −1.61V and mobility ∼100cm2/Vsec.

Image sticking of AMOLED is caused by the property variation of driving transistors. In this paper, we investigated the hysteresis behavior of p-type p-Si thin film transistors as driving device for AMOLED. As the temperature increase, it was observed that hysteresis phenomenon was suppressed. This can be explained by that the trapping and de-trapping rate of carriers is much faster in high temperature than in room temperature.

The electrical characteristics of SiH4-based PECVD gate oxide have been investigated with respect to gate oxide integrity (GOI) and its reliability. It was found that the GOI of poly-Si TFT integrated on glass substrate strongly depended on the charge trapping and deep level interface states generation under Fowler-Nordheim stress (FNS). By applying elevated temperature postanneal without vacuum break after the gate oxide deposition, highly reliable gate oxide was obtained. Under FNS, ID-VG curve showed severe shift and degradation of subthreshold slope, which were reduced by adopting post-annealed gate oxide. Besides, the TFT with post-annealed gate oxide showed around 10 times higher charge to breakdown than that of as-deposited gate oxide. Charge to breakdown of MOS capacitors were also studied. By applying post-annealed gate oxide, charge to breakdown drastically improved, which could be explained by reduced charge trapping under FNS.