| Summary: | 碩士 === 國立交通大學 === 光電工程學系 === 100 === With a high mobility (>10 cm2/Vs) than conventional amorphous silicon semiconductor and a low operating voltage (< 5 V) and small sub-threshold voltage swing, amorphous In-Ga-Zn-O thin-film transistors (a-IGZO TFTs) draw a lot of attentions. Besides, due to a low temperature process and high transparency, a-IGZO TFTs is suitable to develop on flexible displays. However, when a-IGZO TFTs are developed for low-power consumption, high-frequency operating of circuit, improved electron mobility and a low parasitic capacitance are required.
In this study, we found the carrier mobility significantly increase by a silicon capping layer on the back channel. We presume that the oxygen in IGZO films be captured by silicon and transfer to the silicon surface or bulk. Therefore the oxygen vacancy is created to dramatically increase the carrier concentration and leaded the mobility significantly improved. Hence, we propose a structure with silicon capping layer onto the active layer of bottom-gate a-IGZO TFT to provide a powerful solution of enhancement of device performance that would not cause current leakage and performance degradation. The method of Si capping layer is a simple and effective approach to fabricate a feasible metal oxide transistor. Besides, we also use co-sputtered a-IGZO/IZO to improve the mobility, incorporating with the Si capping layer and changing the capping ratio or position to find the physics behind. Moreover, we try to passivate the device without changing the characteristics to improve the stability so that we could apply to the present display technology.
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