Simulation and analysis of the I - V characteristics of a Schottky diode containing barrier inhomogeneities

Abstract

The current - voltage (I - V) characteristics of Schottky diodes containing barrier inhomogeneities have been simulated using thermionic emission - diffusion (TED) theory and assuming a Gaussian distribution of barrier heights. The system is considered to have a number of non-interacting parallel diodes with each corresponding to a different barrier height within the distribution limit. The mean and the standard deviation of the Gaussian distribution are taken either as constant or having linear bias dependences. The simulated I - V data are then analysed to study the effects of the distribution parameters and their bias coefficients on the barrier height and the ideality factor over a temperature range of 50 - 300 K. It is shown that the mere existence of a distribution causes a decrease in the zero-bias barrier height and, in turn, leads to nonlinearity in the activation energy plots. Also, the decrease is greater for high values of standard deviation. Further, the abnormal increase of ideality factor with decrease in temperature occurs due to the bias dependence of the standard deviation of the distribution. Finally, it is demonstrated that the decrease in temperature and increase in standard deviation cause similar effects and both lead to a decrease in barrier height and an increase in ideality factor. Also, the role of the series resistance in adversely influencing the linearity of the log(I) - V characteristics of a Schottky diode containing barrier inhomogeneities is discussed.