Admittance of metal-insulator-semiconductor tunnel contacts in the presence of donor-acceptor mixed interface states and interface reaction

The admittance of a metal-insulator-semiconductor tunnel contact is evaluat ed considering the presence of donor-acceptor mixed interface states and ch emical reaction in the interfacial oxide layer. Both the voltage and freque ncy behavior of the device has been studied. It has been found that, due to interface reaction, the current, conductance, and capacitance of the devic e drift considerably with time yielding an aging effect. Further, it is rev ealed that the dependence of the conductance and capacitance on the aging t ime stem rapidly from changing time constants of the interface states with aging time. The results are discussed with special reference to well known admittance spectroscopy used for the characterization of interface states. (C) 2001 American Institute of Physics.