The analysis of I-V characteristics of Schottky diodes by thermionic emission with a Gaussian distribution of barrier height

The current-voltage (I-V) characteristics of Al/p-Si Schottky barrier diode (SBD) with native insulator layer were measured in the temperature range of 178-440K. The estimated zero-bias barrier height Phi(Bo) and the ideality factor n assuming thermionic emission (TE) theory have shown strong temperature dependence. Evaluation of the forward I-V data have revealed an increase of zero-bias barrier height Phi(Bo), but the decrease of ideality factor n with the increase in temperature. The experimental and theoretical results of the tunneling current parameter E-o against kT/q were plotted to determine predominant current-transport mechanism. But the experimental results were found to be disagreement with the theoretical results of the pure TE, the thermionic-field emission (TFE) and the field emission (FE) theories. The conventional Richardson plot has exhibited non-linearity below 240 K with the linear portion corresponding to the activation energy of 0.085 eV and Richardson constant (A*) value of 2.48 x 10(-9) A cm(-2) K-2 which is much lower than the known value of 32 A cm(-2) K-2 for holes in p-type Si. Such behaviours were attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (BHs) due to barrier height inhomogeneities that prevail at interface. Thus, the modified In(I-o/T-2) q2 sigma o2/2k(2)T(2) vs q/kT has plotted. Then A* was calculated as 38.79 A cm(-2) K-2 without using the temperature coefficient of the barrier height. This value of the Richardson constant 38.79 A cm(-2) K-2 is very close to the theoretical value of 32 A K-2 cm(-2) for p-type Si. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Al/p-Si Schottky barrier diodes with native insulator layer can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights. (C) 2010 Elsevier Ltd. All rights reserved.