Short-living excitations and relaxation processes in ion-implanted and ion beam-mixed silica-silicon systems for optoelectronic application

• Applicant: Professor Dr. Hans-Joachim Fitting
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2012 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 222808387

The project is devoted to the investigation of the electronic structure and dynamics of the excited states for both the low-dimensional oxide systems and bulk nanostructured materials subjected to ionizing radiation treatments. The main goal of the project is to study the physical nature and evolution of short-living energy states and their luminescence features within thin-films, amorphous and nanostructured modifications of silicon dioxide and silicabased materials containing radiation defects, nanoclusters and nanocrystals. The actuality of the project proposed is based on the new possibilities for new functional structures design for optoelectronics and photonics as well as photovoltaic industries which could provide a better information processing performance. The different silica modifications with varying atomic disorder and dimensionality (glasses, glass ceramics and thin films 20 - 500 nm thick) irradiated by electrons and implanted with Si, Ge, C, Sn, Pb, Zn ions will be the samples under study. Especially the ion beam-mixed Si02/Si interfaces should be investigated by electron microscopic methods EFTEM, STEM imaging, and EELS spectroscopy. The maximum concentralion of implanted Si+ ions will be located near the SiO2-Si interface region leading there to an ion beam mixed gradual SiOx (2 > x > 0) buffer region, doped with implanted ions which is even extended into the Si substrate by atomic collisions (knocking-off and knocking-on processes) during ion implantation.The dynamics and mechanisms of the fast dissipative processes involving the localized electronic states of optically-active nanoclusters, point defects and aggregates incorporated into the ion-modified matrices of silicon dioxide and its analogs. It is planned to use the methods of optical non-stationary photoelectron spectroscopy, pulse photo- and cathodoluminescence which all have shown their high information retrieving ability during the investigations of atom and defect clusters and their evolution depending on size, implantation conditions and post-irradiation treatment regimes. The synchrotron radiation source as well as pulsed electron beam accelerators will be used to study the regularities of the surface short-lived excited states behavior. In order to understand the nature of highenergy excited states a combined approach will be used involving both the state-of-the-art time-resolved spectroscopy techniques and computer modeling.

• DFG Programme: Research Grants