Preparation And Physico-chemical Properties Of Porous Silicon By Au/Ag-assisted Chemical Etching

Porous silicon has attracted wide attention due to its large specific surface area,high reactivity and high compatibility with silicon-based microelectronics processes.Traditional electrochemical methods do not use large-scale preparation of porous silicon.Therefore,it is important to study Metal-assisted Chemical Etching preparation technology.The thesis focuses on the preparation of porous silicon by chemical etching,and develops the preparation method of catalytic metal particles,the electrostatic adsorption process of metal particles on the surface of silicon wafers,the process conditions for preparing porous silicon by metal-assisted chemical etching,and the combustion of porous silicon/Na Cl O₄ composite energetic materials.Performance and other research,the main research content is as follows:（1）Ag and Au nanoparticles are prepared by reducing Ag NO₃and HAu Cl₄ with trisodium citrate（Na₃Ct）.The diameter of Ag particles prepared at n（Na₃Ct）/n（Ag NO₃）=1.9 is 60 nm,and when n（Na₃Ct）/n（HAu Cl₄）=5.4,Au particles of about 30 nm are obtained.Both metal particles are negatively charged;The silicon wafers treated with H₂SO₄/H₂O₂ for 30 min at 150℃to hydroxylate,1m M APTES toluene solution for silanization,then the silicon wafer and metal particles combined with electrostatic adsorption deposition,the metal particles on the surface of the silicon wafer showed a uniform and independent monolayer distribution.（2）Using gravimetric analysis and electrochemical testing to study the catalytic effect of Ag and Au,it was found that Au has a better catalytic effect;explore the types of additives（DMAC,DMF and Et OH）,etching time and the ratio of HF/H₂O₂ in the etching solution.The effect of corrosion conditions on the physical and chemical properties of porous silicon.The etching system with Et OH added is faster than DMF and DMAC in the longitudinal corrosion rate,and in the lateral corrosion rate,it shows the action law of DMAC,DMF,and Et OH in turn;the product film thickness gradually increases with the increase of the etching time.The porosity reaches the maximum value at t=90 min and then decreases;the thickness of the porous silicon film increases first and then decreases with the increase of the ratio of HF/H₂O₂,and the maximum film thickness can reach 477μm atρ=70%.（3）Using explosive spectroscopy and DSC thermal analysis to optimize the preparation conditions of the porous silicon-based composite material,it was found that the maximum energy intensity of the explosive spectrum of the porous silicon/Na Cl O₄composite material increased with etching time,and the etching solutionρ=70%the explosive light intensity is the largest.When DMAC is selected as the additive,the explosion effect is better than DMF and Et OH.The DSC thermal analysis results show that the porous silicon/Na Cl O₄ composite prepared by the DMAC andρ=70%etching for180 min has a heat release of up to 1370.3 J/g,which of DMF and Et OH products under the same conditions is 1287.5 J/g and 832.6 J/g.