a Department of Microelectronics, Fudan University, Shanghai 200433, China; b Department of Solid State Sciences, Gent University, Krijgslaan 281/S1, B-9000, Gent, Belgium
Abstract The forward current--voltage (I--V) characteristics of polycrystalline CoSi2/n-Si(100) Schottky contacts have been measured in a wide temperature range. At low temperatures (≤200K), a plateau-like section is observed in the I--V characteristics around 10-4A·cm-2. The current in the small bias region significantly exceeds that expected by the model based on thermionic emission (TE) and a Gaussian distribution of Schottky barrier height (SBH). Such a double threshold behaviour can be explained by the barrier height inhomogeneity, i.e. at low temperatures the current through some patches with low SBH dominates at small bias region. With increasing bias voltage, the Ohmic effect becomes important and the current through the whole junction area exceeds the patch current, thus resulting in a plateau-like section in the I--V curves at moderate bias. For the polycrystalline CoSi2/Si contacts studied in this paper, the apparent ideality factor of the patch current is much larger than that calculated from the TE model taking the pinch-off effect into account. This suggests that the current flowing through these patches is of the tunnelling type, rather than the thermionic emission type. The experimental I--V characteristics can be fitted reasonably well in the whole temperature region using the model based on tunnelling and pinch-off.
Received: 16 July 2001
Revised: 27 August 2001
Accepted manuscript online:
PACS:
73.30.+y
(Surface double layers, Schottky barriers, and work functions)
Fund: Project supported by a Bilateral Cooperation Programme (Bil 96/74/B017) from the Flemish Ministry of Science and Technology and Technology Ministry of China, and in part by the National Natural Science Foundation of China (Grant No. 69876007).
Cite this article:
Zhu Shi-Yang (竺士炀), Ru Guo-Ping (茹国平), Qu Xin-Ping (屈新萍), Li Bing-Zong (李炳宗), R.L.Van Meirhaeghe, C.Detavernier, F.Cardon Double threshold behaviour of I--V characteristics of CoSi2/Si Schottky contacts 2002 Chinese Physics 11 156
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