The Preparation And Optic Properties Of Monocrystalline Silicon Raman Substrate Based On Anisotropic Etching

Along with people's living standards unceasing enhancement,the Chinese food resources become more and more abundant,in the same time people are taking more attentions to food safety.The traditional detection technology has been unable to meet people's requirements,the development of an accurate and efficient detection of pesticide and food additives residue technology is imminent.Raman scattering as a powerful tool for the analysis of substances molecular structure,especially since the surface-enhanced Raman scattering(SERS)has been found.The SERS effects not only overcome the interference of the surface fluorescence,but also increases the intensity of the Raman scattering.So the preparation of Raman active substrate is a key step to achieve SERS application.However,the commercial Raman substrate is expensive,and there is no large area uniform size,shape control,enhances the effect of significant,easy production of Raman active substrate.In this paper,we use the alkaline solutions on the surface of the monocrystalline silicon anisotropy etching,in the monocrystalline silicon surface preparation of uniform size,wide coverage,and morphology control monocrystalline silicon microstructures.A new type of additive,borax(Na2B4O7·10H2O),was added to the NaOH solution,and the concentration of NaOH,Na2B4O7·10H2O,the time and temperature of the preparation were investigated by controlled variable tests.The optimum conditions were as follows: NaOH concentration was 2wt%,etching temperature was 85 ?,etching time was 25 min,and Na2B4O7·10H2O concentration was 2.2wt%.The coverage rate of monocrystalline silicon surface pyramid obtained after etching was about 99.0%,and the average size was only 3.54?m,which reached the requirement of preparing SERS active substrate.The nano-gold particles with different thicknesses were deposited on the microstructure of monocrystalline silicon surface by vacuum coating,and the monocrystalline silicon surface enhanced Raman substrate with different nano-gold thickness was prepared.The enhancement performance of the monocrystalline silicon surface enhanced Raman substrate was tested using a QE65 pro Ramanspectrometer.The results showed that the optimum thickness(expressed here as a sputtering time)was plated at 20 mA for 5.5 min.Using the monocrystalline silicon Raman substrate prepared at the best coating thickness to test methylene blue ethanol solution,founding that the detection limit reached 1 × 10-5mol / L,and all the characteristic peaks of the methylene blue probe molecule could To distinguish.SERS test results showed that monocrystalline silicon surface enhanced Raman substratehas good Raman activity.At the same time,the preparation of the metal microstructure is simple,the cost is low,the size and morphology is controllable,which providing a possible mean to reduce the cost of food testing with a potential application value.