| Summary: | 碩士 === 國立交通大學 === 電機學院光電顯示科技產業專班 === 95 === On study the grain boundary (GB) effects, the comparison of electrical stability between GB and NGB TFT has been demonstrated. The NGB TFT owns superior conducting ability than the GB TFT which contains a 100-nm trap-numerous region at the middle of the channel. The influence of protrusion grain boundary on the degradation of crystallized laterally grown Polycrystalline Silicon Thin Film Transistors is investigated. Nevertheless, the distinct electrical behaviors of the TFTs were demonstrated under the AC gate bias stress. Due to the existence of protrusion in the channel, GB TFT shows weaker endurance against the AC gate pulse stress than that of NGB TFT. The magnitude of the vertical field at the protrusion is stronger than the other regions in GB TFT. The strong electric field would lead to the state creation and charge trapping at the protrusion and reduce the device’s electrical performance. We investigate the basic electric characteristics of the poly Si TFT which has the different of GB position in the channel with respect to the source junction. The degradation of TFT with protrusion grain boundary is more severe and the different damage of the source/drain junction in the TFT with grain boundary closed to source side. We also try to change the voltage waveform that will be divided into four parts; rising time, T Vg_high, falling time and the T Vg_low; and to investigate that how the ac stress waveform influences the degradation of the poly Si TFTs. The device degradation is strongly dependent on the falling time (Tf ) and the time at low level
(T Vg_low).
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