Study of the Drain Leakage Current in Bottom-Gated Nanocrystalline Silicon Thin-Film Transistors by Conduction and Low-Frequency Noise Measurements |
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Authors: | Hatzopoulos A T Arpatzanis N Tassis D H Dimitriadis C A Oudwan M Templier F Kamarinos G |
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Affiliation: | Dept. of Phys., Aristotle Univ. of Thessaloniki; |
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Abstract: | The drain leakage current in n-channel bottom-gated nanocrystalline silicon (nc-Si) thin-film transistors is investigated systematically by conduction and low-frequency noise measurements. The presented results indicate that the leakage current, controlled by the reverse biased drain junction, is due to Poole-Frenkel emission at low electric fields and band-to-band tunneling at large electric fields. The leakage current is correlated with single-energy traps and deep grain boundary trap levels with a uniform energy distribution in the band gap of the nc-Si. Analysis of the leakage current noise spectra indicates that the grain boundary trap density of 8.5 times 1012 cm -2 in the upper part of the nc-Si film is reduced to 2.1 times 1012 cm-2 in the lower part of the film, which is attributed to a contamination of the nc-Si bulk by oxygen |
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