Study of leakage current inn-channel andp-channel polycrystalline silicon thin-film transistors by conduction and low frequency noise measurements
作者:
C. T. Angelis,
C. A. Dimitriadis,
I. Samaras,
J. Brini,
G. Kamarinos,
V. K. Gueorguiev,
Tz. E. Ivanov,
期刊:
Journal of Applied Physics
(AIP Available online 1997)
卷期:
Volume 82,
issue 8
页码: 4095-4101
ISSN:0021-8979
年代: 1997
DOI:10.1063/1.365720
出版商: AIP
数据来源: AIP
摘要:
The off-state current inn- andp-channel polycrystalline silicon thin-film transistors (polysilicon TFTs) is investigated systematically by conduction measurements at various temperatures and low-frequency noise measurements at room temperature. It is demonstrated that the leakage current is controlled by the reverse biased drain junction. The main conduction mechanisms are due to thermal generation at low electric fields and Poole–Frenkel accompanied by thermionic filed emission at high electric fields. The leakage current is correlated with the traps present in the polysilicon bulk and at the gate oxide/polysilicon interface which are estimated from the on-state current activation energy data. Analysis of the leakage current noise spectral density confirms that deep levels with uniform energy distribution in the silicon band gap are the main factors in determining the leakage current. The density of deep levels determined from noise analysis is in agreement with the value obtained from conductance activation energy analysis. The substantially lower leakage current observed in then-channel polysilicon TFT is explained by the development of positive fixed charges at the interface near the drain junction which suppress the electric field. ©1997 American Institute of Physics.
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