Nature of interface traps in Ge metal-insulator-semiconductor structures with GeO_2 interfacial layers

摘要

The nature of interface traps in Ge metal-insulator-semiconductor (MIS) structures with GeO_2 interfacial layers have been systematically investigated at various temperatures by C-V method and the conductance method including surface potential fluctuations. The nature of interface traps was found to depend on the oxidation temperature. Furthermore, the charged center density evaluated from the magnitude of the surface potential fluctuations (which includes charged interface traps, charged slow traps, and fixed oxide charges) increases from the valence bandedge (VBE) to the conduction bandedge (CBE) of Ge in the case of high-temperature oxidation when the Fermi level moves from the VBE to the CBE. This indicates that acceptorlike traps are distributed across the Ge bandgap.