In this thesis, the poly-Si TFTs with different channel width and channel length are successfully fabricated and characterized. In particular, by using the T-gate structure and body contact, we can measure the substrate current and body voltage. Therefore, short channel effects in polycrystalline silicon thin-film transistors are investigated clearly. In order to study impact ionization effect and floating body effect more carefully, we measure and compare the electrical behaviors of device with different grain boundary trap density, grain size, and channel dimension. The influences of these factors on the short channel effects are also discussed and explained.
In this experiment, it is found that the devices with short channel length, exhibit improved normalized turn on current and smaller threshold voltage. But on the other hand the sever kink effect which generated by the impact ionization also observed. Moreover, the floating body under the channel region serve as a parasitic BJT as in silicon-on-insulator devices. The related single transistor latch-up is observed and discussed for short-channel devices with various channel width.
The severe impact ionization effects in polycrystalline silicon thin-film transistors are investigated and characterized. By directly measuring the substrate current from conventional TFTs with body contact, the impact-ionization effects can be characterized and analyzed very clearly. An anomalous substrate current under high gate voltage is observed. The parasitic tunneling effect between inversion region and body region is proposed to explain this phenomenon. Finally, a physically-based model is established and compared with the measured substrate current. Good agreements are found when the vertical field scattering effect is included into the maximum electric field impact ionization model.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0716103-144552 |
| Date | 16 July 2003 |
| Creators | Chen, Shih-Ching |
| Contributors | none, none, none, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0716103-144552 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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