Evidence for the double distribution of barrier heights in Pd2Si/n-Si Schottky diodes from I-V-T measurements

The current-voltage (I-V) characteristics of palladium silicide-based Schottky diodes on n-type silicon have been measured over a wide temperature range (66-300 K). Their analysis on the basis of the thermionic emission-diffusion (TED) mechanism reveals an abnormal decrease of zero-bias barrier height and increase of ideality factor with decrease in temperature (T) and nonlinearity in the activation energy plot. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the silicide/silicon interface. Evidence is given for the existence of a double Gaussian distribution having mean barrier heights of 0.79 V and 0.64 V and standard deviations of 0.081 V and 0.057 V with ideality factors 1.064 and 1.363, and remain effective in the temperature range 134-300 K and 66-120 K respectively. Further, the effect of forward bias on the distribution parameters is discussed. A simple method, involving the use of a zero-bias barrier height versus inverse temperature plot, is suggested to deduce the presence of single/multiple distribution(s) of barrier heights and to determine the respective parameters.