Preparation And Properties Of Porous Silicon Based On Metal Assisted Chemical Etching

Porous silicon materials have attracted widespread attention for its high explosive properties,less environmental pollution and good compatibility of silicon-based microelectronics process,but its fabrication is still limited by the traditional electrochemical synthesis method,which consumes plenty of energy and not suitable for mass production.Therefore,it is significant for application to develop a more convenient chemical preparation method.In this paper,porous silicon was prepared by Metal Assisted Chemical Etching on the basis of metal salt reduction and deposition on single-polished P-type silicon wafer,and the preparation of porous silicon by Cu and Ag assisted chemical etching was compared.Then the Porous silicon/Ga(NO₃)₃ composite energetic material with explosion capacity was constructed and their explosive merits were researched.The main research contents are as follows:(1)Firstly,Cu metal was used for metal deposition,and ascorbic acid(VC)was used to reduce copper nitrate under the protection of PVP.The effects of reductant ascorbic acid and copper nitrate concentration on metal deposition were studied respectively.The results showed that the appropriate concentration of VC was 0.2mol·L^-1,and copper nitrate concentration was 1mmol·L^-1.The morphology changes of metal in different corrosive solutions were explored,and the best corrosion morphology and energetic effect can be obtained when V(HF):V(H₂O₂)was 5:1.The porosity of porous silicon under this route was 17%and thickness was 17?m,the spectrum characterization intensity was 800.(2)Then the Ag metal was used for etching,the results showed that the optimum concentration of VC was 0.6 mol·L^-1 and the concentration of Ag NO₃was 1 mmol·L^-1when the morphology of the particles was better.Through thickness and porosity characterization of porous silicon film under different corrosive solution,the results showed that the porous silicon at 5:1 has the best corrosion morphology,whose porosity can reach 23%and thickness was 32?m.In this case,the spectral strength was obviously increased to more than 2000 and the explosion phenomenon was obvious.(3)Taking the Ag assisted chemical etching as the research object,the corrosion mechanism of this method was verified by a weight-loss method and Tafel method.The deposition morphology of Ag particles was controlled by the orthogonal experiment.When the level combination of each factor was 0.5 mol·L^-1 dispersant PVP and 3mmol·L^-1 Ag NO₃ mixed by 3:1,0.6 mol·L^-1 of ascorbic acid was used,then mixed and stirred,by which the Ag nanoparticles with the particle size uniform morphology and good dispersion around 100 nm was fabricated.The characterization of porous silicon results show that the well-dispersed Ag nanoparticles can adjust the structure of etching structure,and the PS/Ga(NO₃)₃ energetic material with better performance was obtained.(4)The explosion mechanism of PS/Ga(NO₃)₃ composite energetic materials was studied by FT-IR and chemical bond analysis.The results showed that the explosion of PS/Ga(NO₃)₃ results from the violent interaction between the porous silicon and the NO₃ ligand in gadolinium nitrate,and the product is NO₂.