tailieunhanh - báo cáo hóa học:" Optical sensing nanostructures for porous silicon rugate filters"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Optical sensing nanostructures for porous silicon rugate filters | Li et al. Nanoscale Research Letters 2012 7 79 http content 7 1 79 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Optical sensing nanostructures for porous silicon rugate filters Sha Li Dehong Hu Jianfeng Huang and Lintao Cai Abstract Porous silicon rugate filters PSRFs and combination PSRFs C-PSRFs are emerging as interesting sensing materials due to their specific nanostructures and superior optical properties. In this work we present a systematic study of the PSRF fabrication and its nanostructure optical characterization. Various PSRF chips were produced with resonance peaks that are adjustable from visible region to near-infrared region by simply increasing the periods of sine currents in a programmed electrochemical etching method. A regression analysis revealed a perfect linear correlation between the resonant peak wavelength and the period of etching current. By coupling the sine currents with several different periods C-PSRFs were produced with defined multiple resonance peaks located at desired positions. A scanning electron microscope and a microfiber spectrophotometer were employed to analyze their physical structure and feature spectra respectively. The sensing properties of C-PSRFs were investigated in an ethanol vapor where the red shifts of the C-PSRF peaks had a good linear relationship with a certain concentration of ethanol vapor. As the concentration increased the slope of the regression line also increased. The C-PSRF sensors indicated the high sensitivity quick response perfect durability reproducibility and versatility in other organic gas sensing. Background Porous silicon PSi a material with unique structural and optical properties can be prepared by anodic etching of silicon in ethanolic hydrofluoric acid solution 1-3 . By changing the current density the porosity of PSi that decides the refractive index can be tailored in a wide range and thus it is able to obtain many types of PSi .