In order to prevent the interdiffusion and reaction between the metal and semiconductor,an insulator/oxide layer such as SiO2,SnO2,TiO2,Si3N4 and an organic layer is generally inserted at the metal/semiconductor interface.Thus a metalsemiconductor (MS) structure is converted to a metalinsulator/oxide-semiconductor (MIS/MOS) structure.Such an insulator layer not only prevents the reaction and interdiffusion between metal and semiconductor,but also alleviates the electric field reduction issue of these structures.When an exteal bias voltage (or electric field) is applied across the MOS structures or capacitors,the contribution of the interfacial oxide layer,depletion layer,interface states (Nss) and series resistance (Rs) share this applied bias voltage.In this respect,the interfacial oxide layer and its thickness,frequency,and applied bias voltage can have considerable influence on electrical and dielectric properties of these structures.