The Controllable Fabrication And Graphical Research Of Single-crystal SiNW Arrays

With the development of nanotechnology,monocrystalline silicon nanowires(SiNWs)as a one-dimensional nano-materials with excellent photoelectric properties make it have great values in the fields of silicon-based nano-optoelectronic devices and sensors.The different microstructures,lengths and morphology make their properties present great various at the nanoscale.Therefore,the preparation of large-area controlled silicon nanowire arrays and the silicon-based patterning preparation based on lithography are of great significance in the improvement of nano / micrometer scale optoelectronic devices.In the present study,we obtained a large-area single-crystal silicon nanowire arrays with controlled length,spacing and diameter by combining nanosphere lithography(NSL)and metal-assisted chemical etching(MACE).The Au meshes with small pore size are obtained by sputtering at a certain inclination angle(60 °)by using the principle of oblique angle deposition(shadowing effect).We can avoid the serious distortion of the PS sphere during the NSL process,and the preparation of SiNWs by the nanosphere mask plate is encouraged well.The length of nanowires is 20?m without congregating and the nanowire spacing is adjustable from 300 nm to 1000 nm and the diameter of nanowires is controlled at submicron level,and the area is in the order of centimeter.At the same time,we study the effects of process conditions such as solution concentration,corrosion temperature and corrosion time on silicon nanowire arrays.Different concentration of the solution will not only make the silicon nanowire array tapering,but also affect the morphology of the silicon nanowires;when the corrosion temperature is too low,the redox process of etching process is slower,making the silicon nanowires etched difficult to occur.However,the redox reaction is too severe when the etching temperature is high.The reaction process will generate large amounts of gas,making Au mesh film damaged and corrosion results are poor.Therefore,we can control the appropriate time to get silicon nanowire arrays neither congregated nor tapered.Then,we use the metal-assisted chemical etching method to prepare the micro-patterned template based on the photolithography technique,and analyze the effect of different processing conditions on the preparation.Finally,the morphology,composition,microstructure,growth orientation,PLproperties and light absorption of the silicon nanowires were characterized by SEM,EDS,TEM,XRD,fluorescence spectra and UV-visible.In particular,by analyzing the UV spectra of silicon nanowire arrays,we have obtained a low reflectivity(less than10%)antireflective structure of silicon nanowire in the range of 200nm-1000 nm.This good antireflection property is due to the special structure of the silicon nanowire itself goose feather to make it have a higher specific surface area.We further analyze the single silicon nanowires by transmission electron microscopy,and observe that the surface of single silicon nanowires have higher roughness,which can further enhance the absorption of visible light.