Electronic and thermal reaction pathways in the synchrotron radiation-excited modification and epitaxy of silicon-based materials

When the core electronic states of atoms in solids are excited by intense high-energy photons (hν > 100 eV), a situation where the excited atoms are at energetically high levels while the surroundings are frozen is realized. Irradiation by a synchrotron radiation beam places a material in such a state, which leads to extensive movement of the constituent atoms. In the first half of this paper, results on how synchrotron radiation illumination causes the modification of several silicon-based materials, i.e., a-SiO2, a-Si3N4, a-SiNx:H, a-Si:H, and a-Si are described. A means for distinction between purely photolytic and thermally assisted mechanisms is presented. Factors affecting the consequence include chemical potentials in the network's topological structure, ionicity of the chemical bonds, and types and numbers of vacancies contained in the network. In the second half, synchrotron radiation-excited epitaxy of short-period Si/Si1−xGex multiple quantum wells and SinGem strained-layer superlattices is demonstrated. The atomically abrupt interfaces, similar to those obtained by solid-source molecular beam epitaxy, and the atomic-scale controllability of thickness are illustrated by real-time characterization of structural parameters through spectroscopic ellipsometry.