The Fabrication And Application Of Square Silicon Nanoholes

Silicon nano-materials, especially one-dimensional silicon material because of its characteristics of size show quantum confinement effect, the small size effect, macroscopic quantum tunneling effect and surface effect and other characteristics different with bulk materials, and showed unusual mechanical, optical, electrical, magnetic, thermal and chemical properties, has become researching focus of international semiconductor materials and nano-materials.Basically, such as integrated circuits and photovoltaic devices are based on silicon substrate, so silicon nanowires, silicon nanoholes, porous silicon and silicon nanotubes and other one-dimensional silicon nanostructures would be connected with bulk silicon substrate, which is important for extensive use of silicon nanomaterials.This paper does not use any template and special technical, large-area and uniform size square silicon nanoholes are produced by combining metal-assisted catalyzed etching with anisotropic etching of silicon. The factors affected the growth of square silicon nanoholes were explored.Because Ag nanoparticles has an important auxiliary catalytics on the corrosion of silicon, and dispersed silver nanoparticles is more conducive to the growth of silicon nanoholes, so we concentrated on controlling of the morphology of silver nanoparticles. We changed annealing conditions such as the silver film thickness, heating rate and cooling rate, holding time and protective atmosphere, and studied the influence of different process parameters on the formation of silver nanoparticles. The optimum conditions of synthesis for meeting requirements of Ag nanoparticles is:The thickness of Ag film is 8～10nm, Argon as a shielding gas, heating rate is 100℃/ min, cooling rate is 20℃/min, the annealing temperature is 300℃.We changed etching conditions such as the etching solution concentration, reaction temperature and reaction time, and discussed the influence of different process parameters on the formation of square silicon nanoholes. We explain the the formation of square silicon nanoholes with metal catalytic mechanism and the mechanism of anisotropic etching of silicon. After continuous exploration the best conditions of fabricating square silicon nanoholes is:The concentration of hydrofluoric acid is controlled in 2～5 Mol/L, concentration of hydrogen peroxide is 0.3～0.4 Mol/L, reaction temperature is 50～55℃.The application of square silicon nanoholes is studied. We fabricated square silicon nanoholes/Ag as SERS substrate by immersion plating siliveron square silicon nanoholes. The enhanced Raman spectrum of adenine molecules adsorbed on square silicon nanoholes/Ag substrate is detected by Raman spectroscopy. The results showed that silver/square holes in nano-silicon substrate has a good sensitivity and has potential applications in the field of molecular detection; The integral reflection spectrum of square silicon nanoholes is measured by spectrophotometer. The results show that it has good reflection of the reduction, the low reflectance is about 2% in 250-800nm.