Description:
A new model for the semi-insulating polycrystalline silicon (SIPOS)-silicon interface is proposed. The model explains the behaviour of the capacitance-voltage characteristics of a metal- SIPOS-silicon structure at low temperatures. A theoretical capacitance versus voltage (C–V) relationship has been calculated for low temperatures and fitted to measured data with very good agreement. The interface state density at the SIPOS–silicon interface has also been calculated using Terman’s method. We demonstrate that when determining the energy distributions of interface states between SIPOS and silicon by using C–V technique, thermal equilibrium between the interface and the silicon bulk has to be maintained by making the measurement at low temperature. Measurement at room temperature normally gives too low values of the interface state density, Dit. Dit values of approximately 1013 cm−2 eV−1 were found for the SIPOS-silicon interface with 25 at. % oxygen concentration.