Optically Stimulated Electron Emission from Surface States of SiO2:Ge Films
Thin 30 nm SiO2films on silicon substrate implanted with Ge+ions and flash-annealed at 900°C are investigated by means of optically stimulated electron emission (OSEE). The materials under study may find a number of technological applications in optical devices and ultraviolet sensors. Samples attestation was performed by electron microscopy and x-ray photoelectron spectroscopy (XPS). XPS data revealed strong dependence between the germanium atoms state and annealing time. The application of Urbach rule and power Kane dependence allowed to fit OSEE spectra at different excitation energy ranges and to retrieve the important structure and energy parameters. Observed correlations between parameter values of Urbach-and Kane-related models suggest the implantation-induced changeover of both the vibronic subsystem and energy band structure.