The role of the interface insulator layer and interface states on the current-transport mechanism of Schottky diodes in wide temperature range

In order to interpret in detail the experimentally observed current–voltage–temperature (I–V–T) and capacitance–voltage–temperature (C–V–T) results of Al/p-Si metal–semiconductor Schottky barrier diodes (SBDs) we have been examined the samples in the temperature range of 150–375 K. In the calculation method, to confirm the relationship between the I–V–T and C–V–T results, we have reported a modification which includes the ideality factor, n, and tunnelling parameter δχ1/2 in the forward bias current characteristics. In the intermediate bias voltage region (0.1 < V < 0.6 V), the semi-logarithmic plots of the forward I–V–T curves were found to be linear. From the reverse saturation currents I0 obtained by extrapolating the linear region of curves to zero applied voltage, the values of zero bias barrier heights ϕB0 were calculated at each temperature. The values of ideality factor calculated from the slope of each curves were plotted as a function of temperature. The values of n are 3.41–1.40 indicating that the Al/p-Si diode does obey the thermionic field emission (TFE) mechanism rather than the other transport mechanism, particularly at low temperature. The high value of ideality factors is attributed to high density of interface states in the SBDs. The temperature dependence energy density distribution profile of interface state was obtained from the forward bias I–V–T measurements by taking into account the bias dependence of the effective barrier height and ideality factor. The interface states density Nss decreasing with increasing temperature was interpreted by the result of atomic restructuring and reordering at the metal–semiconductor interface. After the modification was made to the forward current expression, we obtained a good agreement between the values of barrier height obtained from both methods over a wide temperature.