Effects of Ion Beam Etching on the Nanoscale Damage Precursor Evolution of Fused Silica

Ion-Track Template Synthesis and Characterization of ZnSeO3 Nanocrystals

ZnSeO3 nanocrystals with an orthorhombic structure were synthesized by electrochemical and chemical deposition into SiO2/Si ion-track template formed by 200 MeV Xe ion irradiation with the fluence of 107 ions/cm2. The lattice parameters determined by the X-ray diffraction and calculated by the CRYSTAL computer program package are very close to each other. It was found that ZnSeO3 has a direct band gap of 3.8 eV at the Γ-point. The photoluminescence excited by photons at 300 nm has a low intensity, arising mainly due to zinc and oxygen vacancies. Photoluminescence excited by photons with a wavelength of 300 nm has a very low intensity, presumably due to electronic transitions of zinc and oxygen vacancies.

Towards Investigating Surface Quality of Single-Crystal Silicon Optics Polished with Different Processes

A series of cleaning and etching experiments utilizing organic solvent or weak alkali solutions were performed on single-crystal silicon optics polished with different processes. Polishing-introduced fractured defects in the subsurface layer were systematically characterized using laser-induced scattering imaging and photothermal weak absorption imaging techniques. A white-light interferometer also measured the surface morphology and roughness of the samples to evaluate the surface quality of the optics. The results show that the organic solvent cleaning process can eliminate the surface contamination resulting from the environment and the near-surface polishing-introduced impurities but can not remove the fractured defects in the subsurface layer of the optics. By contrast, weak alkali solution can effectively expose the subsurface defects and decrease the concentration of the embedded absorbing impurities to some extent. The results also imply that the polishing process has a crucial effect on the surface quality (e.g., surface roughness and error) and optical performance (e.g., surface absorption) after the subsequent treatments such as cleaning or etching. The corresponding methodology of cleaning and characterization can serve as a predictive tool for evaluating the polishing level and laser damage resistance of the single-crystal silicon optics.