Determining the thermal generation rate of minority charge carriers at semiconductor-ultrathin oxide interfaces

A simple proximate method for determining the generation rate Gs of electron-hole pairs in metal-ultrathin oxide-semiconductor (MOS) structures is proposed. This method is based on measurements of dynamic current-voltage characteristics of MOS structures in the region of deep depletion of the semiconductor surface and on the comparison of these data to a quasi-equilibrium volt-farad characteristic (VFC) of an ideal MOS structure. This approach to determining Gs from the value of the structure capacitance is insensitive either to a shift of the VPC, which is caused by the presence of built-in charges, or a recharge of localized electron states in the oxide and at the Si-SiO2 interface. The proposed technique also allows one to take the influence of a tunneling current through an insulator on the measurement results into account. The algorithm was tested in studies of generation and annihilation processes of centers of generation of electron-hole pairs in n-Si-based MOS structures with an ultrathin (≅4 nm) oxide.