On the existence of a distribution of barrier heights in Pd2Si/Si Schottky diodes

The current-voltage characteristics of Pd2Si based Schottky diodes on both n- and p-type silicon measured over a wide temperature range (52-295 K) have been interpreted on the basis of thermionic emission-diffusion mechanism and the assumption of a Gaussian distribution of barrier heights. It is shown that while the occurrence of a distribution of barrier heights is responsible for the apparent decrease of the zero-bias barrier height (phi(b0)) and nonlinearity in the activation energy plot, the voltage dependence of the standard deviation causes the unusual increase of ideality factor (eta) at low temperatures. Also, it is demonstrated that the forward bias shifts the mean barrier height towards the higher side and causes narrowing of the distribution as well. A simple method, involving the use of phi(b0) vs 1/T data, is suggested to gather evidence for the occurrence of a Gaussian distribution of barrier heights and obtain values of mean barrier height and standard deviation. The experimental results correspond to a mean barrier height of 0.80 V, standard deviation 0.05 V, and ideality factor 1.21 for Pd2Si based Schottky barriers on n-type silicon; these values for p-type silicon are 0.38 V, 0.03 V, and 1.07, respectively. (C) 1996 American Institute of Physics.