Physical explanation of the barrier height temperature dependence in metal-oxide-semiconductor leakage current models

A temperature dependence of the barrier height between silicon and oxide has been proposed by many authors in order to reflect experimental metal-oxide-semiconductor leakage current results. However, no satisfactory physical explanation of this dependence has yet been given. In this letter, the temperature dependence of the observed macroscopic barrier height is explained by thermal fluctuations of the microscopic local barrier height. Because of the exponential relationship between current and barrier height, the decrease of the barrier during the fluctuation has a dominating effect when compared to the increase, leading on the average to a raised leakage current and correspondingly to a lowered average barrier height.