Study On Fabrication And Reflectivity Of Si Light-trapping Nanostructure

With the increasing energy demand and shortage of resources nowadays,people urgently need to develop and use new clean energy.As a sustainable energy utilization method,solar cells have received more and more attention.Among them,crystalline silicon solar cell has always been occupying the mainstream of the global photovoltaic market due to its safety and high efficiency.At present,the photoelectric conversion efficiency of crystalline silicon solar cells needs to be further improved.Reducing the optical loss on the surface of the solar cell is an important mea to improve its efficiency.The preparation of light-trapping nano-structures on the silicon surface can effectively reduce the reflectivity of the surface,then improves the solar cell's efficiency.In this paper,a Finite-Difference Time Domain(FDTD)method was used to simulate different nanorod structures.The effects of duty-cycle,period and height on the reflectivity of the periodic structures were analyzed,and the parameters of the nanostructures were optimized.Besides,the random-size nanorod structures were also simulated and compared with the periodic structures.In the experimental part,the anodic aluminum oxide film was used as a mask to prepare metal nanoparticle arrays by electron beam evaporation.Next,inductively coupled plasma etching was used to fabricate nanorod arrays with different periods and heights.The morphology of metal nanoparticle arrays and nanorod arrays were characterized.We analyzed the effect of etching time on the size of nanorods.We measured the reflectivity of nanorod structures,and compared it with the simulation results.The simulation results showed that the periodic nanorod structures exhibit better light-trapping performance when the duty-cycle is 0.8,the period is 300 nm-400 nm,and the height is 200 nm.The volatility of the reflectivity curve of the random size nanorod structure is similar to that of the periodic structures.The average reflectivity of the periodic structure is lower at large-angle incidence,but the overall light-trapping effect is not significantly different.In the experiment,nanorod arrays with different heights were fabricated.The diameter of nanorods gradually decreased with the increase of etching time,while the height of nanorods increased linearly.In this paper,the nanorod light-trapping structures with much lower average reflectivity were obtained,and the measurement result were consistent with the simulation results.