Study On Spectral Properties Of Porous Silicon

With the gradual maturation of porous silicon technology,porous silicon has attracted great attention and application due to excellent optical and electrical properties for its special micro-structure,wide absorption spectrum,low preparation cost and good process compatibility.The structure and optical properties of porous silicon have great influence on its performance in practical applications.Therefore,from the point of view of porous silicon structure,the optical properties of porous silicon are studied by simulation and experiment.Firstly,the structure and optical properties of porous silicon were studied by simulation.The simulation models of cylindrical and pore-like porous silicon were designed,and the effects of model parameters of the two structures on the optical properties were studied.The simulation results show that the optical properties of pore-like porous silicon structure are related to the depth,radius and porosity of the hole,and the optical properties of the cylindrical structure are affected by the depth,radius and spacing of the column.Secondly,the experimental design and preparation of porous silicon were carried out to study the influence of experimental parameters on the performance of porous silicon.Crack structures with different morphologies were obtained and a crack formation model was established.Through the experiment of the influence of etching time on the morphology and spectrum of porous silicon,it is found that the crack size of porous silicon increases with the increase of etching time,and an isolated structure occurs at a long etching time,and the depth and width of the crack affect the same.The absorption rate is increased first and then decreased.According to the influence of etching current density on porous silicon,it is found that with the increase of current density,the lateral etching of porous silicon is enhanced,the crack size is increased,and the absorption rate is gradually reduced;when the critical current density is reached,polishing phenomenon will occur.And the absorption rate is close to planar silicon.The effect of etching solution on porous silicon shows that when the concentration of HF is small,the etching depth is reduced,the crack spacing is increased,and the absorption rate is decreased.The concentration of C₂H₅OH mainly affects the lateral etching process of porous silicon,when the concentration of C₂H₅OH increases.At the same time,the etching depth is almost constant,but the structural pressure of the surface is reduced,the size of the crack is reduced,and the absorption rate is increased.Finally,a study on the extension of the spectral range of porous silicon high absorption was carried out.In one aspect,the high absorbance spectral range is extended by the preparation of a porous silicon composite structure.Firstly,two simulation models of pore distribution and random distribution of porous silicon were established.Secondly,two kinds of composite porous silicon preparation schemes were designed.The experimental results show that the number of holes in the composite porous silicon surface prepared by low concentration HF solution is small,and the ability to continue to reduce the reflectivity is limited.The composite structure porous silicon prepared by using H₂O₂ can not only accelerate the corrosion rate,but also prepare the composite structure.The number of holes in porous silicon is much higher than that of the former,and has a high absorption rate in a wide wavelength range.On the other hand,the extension of the high absorption spectral range is carried out by preparing a graphene/porous silicon structure.The experimental results show that the graphene/porous silicon structure sample can greatly increase the absorption rate,and achieve an absorption rate of 90%in the wide spectrum range of the near-infrared full-wavelength,and the spectral range of the high absorption rate is extended.