Modified approach to modeling barrier inhomogeneity in Schottky diodes

Abstract

The conventional model describing barrier inhomogeneities in Schottky diodes with a single series resistance leads to many anomalies including crossing over effect in current–voltage–temperature (I–V–T) plots. A new model is therefore proposed here which entails a parallel combination of several diodes, each with its own series resistance. Further, the barrier heights follow a Gaussian distribution function ρ(φ) with a mean barrier height and standard deviation σ. The series resistance is believed to vary inversely with the ρ(φ) value of the concerned barrier height and hence the area occupied. The occurrence of anomalies with the conventional model is examined in depth, and their effective elimination with the proposed model is discussed with the undertaken current simulations. In addition to predicting the increase in apparent barrier height with increase in temperature, decrease in ideality factor with increase in temperature, and elimination of modeling anomalies observed in the conventional model, the model is successful in predicting that apparent barrier height as a function of inverse thermal energy is a quadratic behavior even with a single distribution. This previously required unlikely scenarios involving multiple mean barrier heights and standard deviations with the conventional model. Finally, the description also explains the observed increase in the apparent barrier height with decrease in temperature of a Schottky diode when the values are deduced from the C–V–T data under reverse bias.