Electrical and microstructural characterisation of an ultrathin silicon interlayer used in a silicon dioxide/germanium-based MIS structure

Ultrathin (1.0 nm) Si layers have been deposited on Ge(100) surfaces using remote plasma-enhanced chemical vapour deposition (RPECVD) at 350°C followed by in situ RPECVD deposition of an SiO2 insulating layer. Microstructural data from transmission electron microscopy along with elemental analysis from X-ray photoelectron spectroscopy and ion scattering spectroscopy indicate that the Si layer is present and may be pseudomorphic in nature. The formation of a Si/Ge heterojunction prior to oxide deposition minimises the formation of Ge oxides and thus controls the chemical nature of the Ge surface. Indeed, dramatic improvements in the electrical interfacial characteristics were observed in the SiO2/Si/Ge over the SiO2/Ge MIS structure.