Electrical Characterization of Germanium Oxide/Germanium Interface Prepared by Electron-Cyclotron-Resonance Plasma Irradiation

We have found excellent electrical characteristics in germanium oxide grown by plasma oxidation for germanium metal-insulator-semiconductor gate dielectric applications. An oxygen plasma stream generated by electron cyclotron resonance was used to oxidize a germanium surface without substrate heating. A transmission electron microscope observation revealed that the obtained germanium oxide/germanium interface is atomically smooth. The energy distribution of interface trap density (Dit) in the upper half of the p-type germanium band gap was measured by the ac conductance method. It is shown that the Dit at the midgap is ~6 ×1010 cm-2eV-1 and increases exponentially as the energy increases to the conduction-band edge.