Research On GaAs Nanostructure Solar Cell

With the development of global economy and the growth of population,the problem of pollution caused by fossil energy has become increasingly acute.Thus,People have begun to explore alternatives to traditional energy sources.Solar energy is the most abundant and available renewable energy source on the earth.Solar cells are semiconductor devices that directly use solar energy to generate electricity through photoelectric conversion effects.However,the low energy conversion efficiency and high cost of solar cells have become two major problems that restrict their development.In this paper,we first describe the working principle of solar cells,and leads to the superiority of GaAs materials in the preparation of solar cells by comparing the performance of direct and indirect bandgap semiconductor materials.Then the design principle and superiority of concentrated III-V multi-junction tandem solar cells are introduced.The effects of surface nano-structures,such as nanowires and nanorods based on GaAs,on the performance of solar cells are highlighted.We describe a method for fabricating the surface nanostructures of GaAs solar cells by ICP dry etching using a Si02 nanosphere array as a mask.In the experiment,we improved the air-water interface self-assembly method to prepare a large-area,uniform,dense silica nanosphere patterns.We designed the dry etching process for nanorod structure with a chloride-based chemical reaction-based etching,supplemented with Ar physical shooting and N2 protection;as for nanocone structures we designed a relatively low selective erosion process.Finite-difference time-domain(FDTD)method is used to model and simulate nano-rod and nano-cone arrays.Through the simulation and test of nano-rods with different diameters,the influence of duty ratio on reflectance was analyzed.By comparing the simulation and test results of nano-cones and nano-rods,the influence of nano-structure's shape on reflectance was analyzed.Based on the Huygens-Fresnel principle,a Fresnel lens is designed for a specific wavelength and focal length by the Fresnel half-band method.The antireflection effect of the Fresnel lens and the effect of the focusing effect on the light absorptivity of the active layer in the PN junction region of the sub-cells are analyzed.