Accurate evaluation of Ge metal—insulator—semiconductor interface properties

To accurately evaluate the Ge metal-insulator-semiconductor (MIS) interface trap density (Dit) by employing the conventional method for Si MIS capacitors on Ge MIS capacitors, we have investigated the impact of majority and minority carrier responses on C-V curves and/or the energy distributions of Dit. It is found that the high-frequency C-V curve, which does not include the majority carrier response with interface traps, cannot be obtained near room temperature (RT) even at 1 MHz. Therefore, to accurately evaluate the Dit values using the Terman method, the C-V curve has to be measured at an appropriate temperature. Furthermore, in the conductance method, evaluations by the model including the narrow bandgap effects are needed to obtain accurate Dit of the Ge MIS interface near RT. Through such accurate evaluation, the interface properties with different kinds of interfacial layers have been investigated. Although the GeO2/Ge interface has a low Dit and a fixed oxide charge density, the total charged ce...