Current-voltage characteristics and barrier parameters of Pd2Si/p-Si(111) Schottky diodes in a wide temperature range

Abstract

Current-voltage characteristics of Pd2Si/p-Si(111) Schottky barrier diodes studied over a wide temperature range (60-201 K) are shown to follow a thermionic emission-diffusion mechanism under both the forward and the reverse bias conditions. The barrier parameters as evaluated from the forward I-V data reveal a decrease of zero-bias barrier height ( phi b0) but an increase of ideality factor ( eta ) and series resistance (Rs) with decrease in temperature. Moreover, the changes in phi b0, eta and Rs become quite significant below ~100 K. An In(Is/T2) versus 1/T plot is found to fit well with two straight lines in different temperatures regimes giving an activation energy of 0.33 eV (201-107 K) and 0.24 eV (below 107 K) and an effective Richardson constant of 33 A cm-2 K-2. However, the activation energy of 0.33 eV corresponds to the zero-bias barrier height at absolute zero. An In(Isf/T2) versus 1/ eta T plot is suggested to obtain the flat-band barrier height and the effective Richardson constant; the corresponding values obtained are 0.401 eV and 32.2 A cm-2 K-2 respectively. It is shown that the `T0 effect` cannot account for the apparent increase in ideality factor and decrease of barrier height at low temperatures. Finally, the decrease of barrier height with voltage under the reverse bias condition is attributed mainly to interfacial layer effects with a small contribution due to image force lowering.