Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Patent
1994-03-03
1995-03-28
Mintel, William
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
257 66, 257 72, 257349, 257354, H01L 2978
Patent
active
054019826
ABSTRACT:
In the channel layer of a thin film transistor (TFT), a channel and its drain meet at a transition within a transition region. The channel extends in a first, or horizontal, dimension away from the drain and extends in a second, or vertical, dimension from a side away from the gate to a side toward the gate. The charge carrier densities in the transition region vary in the second dimension in a way that reduces leakage current, because the position of the maximum electric field is moved away from the gate and its magnitude is reduced. Variation of densities in the second dimension can be produced by high angle implantation of a dopant and a counterdopant, providing a transition region between the drain and the channel underneath the gate. Variation of densities in the second dimension can also be produced with non-angled implantation by a process in which a sidewall spacer offsets the drain, providing a transition region that is between the drain and the channel and that can be doped independently of the drain. In a symmetric TFT in which either channel lead can function as a drain, charge carrier densities can vary in the second dimension at the transitions between each channel lead and the channel.
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Kitajima, H., Suzuki, Y., and Saita, S., "Leakage Current Reduction in Sub-Micron Channel Poly-Si TFTs," Extended Abstracts of the 1991 International Conference on Solid State Devices and Materials, Yokohama, 1991, 1991, pp. 174-176.
Hack Michael G.
King Tsu-Jae
Mintel William
Xerox Corporation
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