Double threshold behaviour of I-V characteristics of CoSi2/Si Schottky contacts

• 来源期刊: 中国物理（英文版）
• 学科: 物理学
• 关键词: Schottky barrier height metal-semiconductor contact inhomogeneity
• 年，卷（期）: 2002,（2）
• 页码范围: 156-162
• 页数: 7页
• 分类号: O4
• 语种: 英文

摘要

The forward current-voltage (I-V) characteristics of polycrystalline CoSi2/n-Si(100) Schottky contacts have beenmeasured in a wide temperature range. At low temperatures (≤200K), a plateau-like section is observed in the I-Vmodel based on thermionic emission (TE) and a Gaussian distribution of Schottky barrier height (SBH). Such a doublethreshold behaviour can be explained by the barrier height inhomogeneity, i.e. at low temperatures the current throughpatches with low SBH dominates at small bias region With increasing bias voltage, the Ohmic effect becomes someimportant and the current through the whole junction area exc eeds the patch current, thus resulting in a plateau-likesection in the I-V curves at moderate bias. For the polycrystalline CoSi2/Si contacts studied in this paper, the apparentideality factor of the patch current is much larger than that calculated from the TE model taking the pinch-off effectinto account. This suggests that the current flowing through these patches is of the tunnelling type, rather than thethermionic emission type. The experimental I-V characteristics can be fitted reasonably well in the whole temperatureregion using the model based on tunnelling and pinch-off.