The hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) are widely used as switching elements in LCD displays and large area matrix addressed senor arrays. In recent years, a-Si:H TFTs have been used as analog active components in OLED displays. However, a-Si:H TFTs exhibit a bias induced metastability. This problem causes both threshold voltage and subthreshold slope to shift with time when a gate bias is applied. These instabilities jeopardize the long-term performance of a-Si:H TFT circuits. Nevertheless a-Si:H TFTs show an exponential transfer characteristic in the subthreshold region. Moreover, the typical power consumptions for TFTs in the subthreshold region are in the order of nano-watts, thus making them suitable for low power design. For these reasons, a-Si:H TFT I-V characteristics in the forward subthreshold operation are investigated. First, we have derived the static and dynamic models of a-Si:H TFT in the forward subthreshold region. Second, we have verified our theoretical models with experimental results. Third, we have proven that a-Si:H TFT experiences no subthreshold slope degradation or threshold voltage shift in the forward subthreshold operation. Finally, we have studied a-Si:H TFT current mirror circuit applications. Measurements regarding the fidelity of current matching in the forward subthreshold region have been performed, and results are shown.
| Identifer | oai:union.ndltd.org:WATERLOO/oai:uwspace.uwaterloo.ca:10012/868 |
| Date | January 2005 |
| Creators | Zhu, Lei |
| Publisher | University of Waterloo |
| Source Sets | University of Waterloo Electronic Theses Repository |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | application/pdf, 664632 bytes, application/pdf |
| Rights | Copyright: 2005, Zhu, Lei. All rights reserved. |
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