The Research On Preparation Of Silicon Nanowires By Chemical Etching Method

As we all know, nanostructured materials have attracted great interest in the field of frontier science and technology for years. At the same time, Silicon material has taken an important role on various aspects of solar cell. The silicon nanowires (SiNWs), as a new kind of one-dimensional nanostructured semiconductor material, have attracted wide attention, owning to its superior and unique optical and electrical properties, as a result, the research of SiNWs has gradually become a highlight in the future solar cell research field.Preparation methods of SiNWs consist of laser ablation method, chemical vapor deposition (CVD) method, thermal vapor condensation, template method, chemical etching method, and so on. The chemical etching method has the benefits of simplified operation and lower equipment requirement, and it is fit for the preparation of a certain amount of SiNWs. Nowadays, HF/AgNO3 etching solution is widely used to prepare SiNWs by the method of wet chemical etching with mature process. On the other hand, there are less researches on HF/Fe (NO3)3 etching solution, which is much cheaper than HF/AgNO3. Therefore, the study of chemical etching by using HF/Fe (NO3)3 solutions is of great significance.In this paper, the synthesis, characterization and preparation methods of SiNWs were studied at first. Based on lots of theories and early experiments, the optimized condition of HF/Fe (NO3)3 chemical etching methods were obtained. After the final experiment, the SEM images and other data were obtained and used to discuss.1) The best experimental condition at the etching temperature of 25℃was confirmed:Large-area aligned silicon nanowire arrays with high quality were formed in 0.2mol/L HF and 10mol/L Fe (NO3)3 etching solutions at an etching temperature of 25℃with an etching time of 45min. It is the best etching solution concentration and etching time. The theoretical analysis and experiment results indicated that SiNWs were prepared well. The average length of single crystal nanowire is about 6μm and the diameter is 100-300nm. As a result of measurements and analysis, the reflectance of SiNWs is below 5%.2) Compared with earlier research with HF/AgNO3 etching solution, it is sure the HF/Fe(NO3)3 solution will be more potential in the future preparation of SiNWs, owing to its cheaper cost and good glowing, homogeneous structure and uniform length of single crystal nanowire.3) In addition, by comparing the SEM images and other data, it's found that the longer time the sample was etched, the longer the average length of single crystal nanowire was. But the reflectance of SiNWs didn't continue to reduce after etching for 45min. Instead, it became a little higher after 60min. Therefore 45min was the best time to prepare SiNWs which had the best reflectance.