Preparation Of Zigzag Silicon Nanowires And Their Optical Properties

Silicon nanowiresarray,with special light trapping structure,acting as the antireflection structure of the crystalline silicon solar cells could effectively improve the absorption of light,which laid the foundation for further improving the photoelectrictransformation efficiency.In this paper,a simple and low-cost metal catalytic chemical etching method was adopted,the zigzag silicon nanowire arrays with controllable morphology were successfully fabricated by alternating etching,and the influence of different parameters on the morphology of zigzag silicon nanowires(ZSiNWs)were investigated.Some meaningful results were achieved by testing the anti-reflection performance and minority carrier lifetime of ZSiNWs.The main research contents and conclusions are as follows:(1)In the single solution etching experiment,it was proved that theetching direction was mainly affected by the concentration of H2O2,an anisotropic etching under low concentration and an isotropic etching under high concentration,while theetching rate was mainly affected by HF concentration.In thetwo-solutionsalternating etching experiment with same HF concentrationand different H2O2 concentrations,the possibility of alternating etching method for the fabrication of silicon nanowires was demonstrated.In addition,it was infeasible to prepare the ZSiNWs by unlimitedly increasing the H2O2 concentration.(2)The anisotropic etching and isotropic etching can be strengthened separately by alternating etching between S I([HF]/[H2O2]=9.2M/0.04M)and S Ⅱ([HF]/[H2O2]=2.3M/0.4M),and the morphology of the obtained ZSiNWS was highly controllable.The effects of deposition time,etching time and substrate type on the morphology of nanowires were systematically studied,which contributed to the finding that the deposition time had a significant influence on the morphology of ZSiNWs and the nanowires are uniform and orderly under deposition time of 40s and 80s,the etching time mainly affected the etching depth,and alternating etching method was applicable to non-(100)substrate.(3)ZSiNWs shows an excellent anti-reflection performance,the average reflectivity in the 200-1100nm wavelength is low to 6.6%.The results indicated that the deposition time had little effect on the surface reflectivity,and the surface reflectivity increases obviously with the increase of etching time,up to 10.7%.(4)The ZSiNWs(under deposition time of 40s)are passivated by I-bond,H-bond and SiO2-film respectively,and the minority carrier lifetime of the structure before and after the passivation were tested.These three passivation methods could improve the lifetime of the minority obviously according to the results,but the lifetime of the minority decayed fastly by I-bond and H-bond passivation,only the SiO2-film passivation showed a high stability.Overall,the passivation effectscould be ranked as:SiO2-film passivation>H-bond passivation>I-band passivation.