Effects of interfacial charge on the electron affinity, work function, and electrical characteristics of thinly oxidized semiconductor‐insulator‐semiconductor and metal‐insulator‐semiconductor devices

A phenomenological theory involving interfacial charge is presented to account for the result that the diode constant n at low forward biases might be temperature dependent in some thinly oxidized (≪ 20 Å) semiconductor‐insulator‐semiconductor and metal‐insulator‐semiconductor devices, resulting in parallel I‐V curves. Neither multistep tunneling through the semiconductor space‐charge region, nor conventional thermionic emission over the barrier, can explain the low‐voltage portion of the I‐V characteristics. In this paper it is shown that an interfacial charge redistribution occurs with changes in temperature, resulting in changes in the electron affinity of the base semiconductor and in the work function of the contact material. This results in a linear dependence of n on reciprocal temperature. An explanation is presented to account for the large temperature coefficient that has been observed for both the diffusion potential VD and open‐circuit photovoltage Voc in these devices. And an explanation of the I‐V characteristics in terms of shunt currents is also given.