Possible atomic structures for the sub-bandgap absorption of chalcogen hyperdoped silicon

Single-crystal silicon wafers were hyperdoped respectively by sulfur, selenium, and tellurium element using ion implantation and nanosecond laser melting. The hyperdoping of such chalcogen elements endowed the treated silicon with a strong and wide sub-bandgap light absorptance. When these hyperdoped silicons were thermally annealed even at low temperatures (such as 200~400 oC), however, this extra sub-bandgap absorptance began to attenuate. In order to explain this attenuation of absorptance, alternatively, we consider it corresponding to a chemical decomposition reaction from optically absorbing structure to non-absorbing structure, and obtain a very good fitting to the attenuated absorptances by using Arrhenius equation. Further, we extract the reaction activation energies from the fittings and they are 0.343(+/- 0.031) eV for S-, 0.426(+/-0.042) eV for Se-, and 0.317(+/-0.033) eV for Te-hyperdoped silicon, respectively. We discuss these activation energies in term of the bond energies of chalcogen-Si metastable bonds, and finally suggest that several high-energy interstitial sites instead of the substitutional site, are very possibly the atomic structures that are responsible for the sub-bandgap absorptance of chalcogen hyperdoped silicon.Comment: 18 pages, 3 figures, 1 tabl

Improving spatial resolution of confocal Raman microscopy by super-resolution image restoration

A new super-resolution image restoration confocal Raman microscopy method (SRIR-RAMAN) is proposed for improving the spatial resolution of confocal Raman microscopy. This method can recover the lost high spatial frequency of the confocal Raman microscopy by using Poisson-MAP super-resolution imaging restoration, thereby improving the spatial resolution of confocal Raman microscopy and realizing its super-resolution imaging. Simulation analyses and experimental results indicate that the spatial resolution of SRIR-RAMAN can be improved by 65% to achieve 200 nm with the same confocal Raman microscopy system. This method can provide a new tool for high spatial resolution micro-probe structure detection in physical chemistry, materials science, biomedical science and other areas

Chinese Expansive Soil Canal Project

This paper gives three representative expansive soil canal projects in China. The engineering geological conditions, the properties of the expansive soil, features of the slides and the measures taken for these canal projects are introduced in detail