Evaluation of device quality germanium-germanium oxynitride interfaces by high-resolution transmission electron microscopy

Previous work has shown that germanium oxynitride films grown on Ge substrates by thermal oxidation followed by nitridation provide a passivating dielectric which can be used to fabricate metal-oxynitride-semiconductor field-effect transistors. We have investigated the interfacial microstructure of this semiconductor-dielectric system with high-resolution transmission electron microscopy (TEM) and show that 21-nm-thick germanium oxynitride films grown using this technique are uniform in thickness and interfacially smooth on a scale of ±0.5 nm over lateral peak-to-peak distances on the order of 100’s of nm. The germanium oxynitride was seen to be electron beam sensitive with significant damage to both the oxynitride and the semiconductor-insulator interface being observed after exposure for 15 s to 200 keV electrons at a current density of 2.250 A/cm2 at the specimen.