Study On Micro-nano Structure Array For Enhancing The Absorption Of Light

The optical properties of the device could be improved by fabricating micron and nanometer scale periodic structures on the surface of the device.In recent years,many artificial metamaterials and new optical functional structures have been developed rapidly.It has become one of the current development trends to fabricate micro-nano structures on the surface of optoelectronic device substrate to change the propagation characteristics of light,so as to increase the light energy absorption and further improve the photoelectric conversion efficiency.In this paper,rigorous coupled wave theory and finite difference time domain method are used to calculate and analyze a variety of micro-nano array structures which can enhance light energy absorption.The influence of structure parameters on absorption performance is discussed,which provides a reference for the design of micro-nano structures used to improve light energy absorption.The main contents of this paper are as follows:Firstly,the finite difference time domain(FDTD)method is used to simulate the light absorption performance of the micro-nano array structure,which is composed of square column,cylinder,tower column,hemisphere and other forms of element structure array surface with significant geometric characteristics.Taking silicon material as an example,the absorption of red,green and blue light in the visible region was calculated and analyzed by adjusting the parameters of the cell structure,such as line width,height,period and incident angle.The simulation results show that the micro-nano array structure composed of these typical geometric feature units can significantly improve the light absorption of material with intrinsic small amount of light absorption.The structure is simple and easy to process.Secondly,in order to solve the problem of low absorptivity of common substrate materials used in the near-infrared band of optoelectronic devices,based on the aboved typical micro-nano structure array,several composite micro-nano structure arrays are designed:silicon column composited with Ag nanoparticles,silicon column composited with Ag pit and graphene-metal grating composite structure.By changing the period,duty cycle,column height of the array structure and the size of the auxiliary metal structure,the influence of different parameters on the absorption performance of the composite microstructure is discussed and analyzed.Finally,the optical absorption of the micro-nano composite structure is enhanced compared with that of the silicon plate and the silicon grating without any auxiliary materials,which provides a new method to improve the optical absorption.Finally,the experimental sample was processed,and its absorptivity was tested and analyzed.In the near infrared band,the high penetration absorption of silicon column micro-nano array structure is zero,so the visible light band of 0.40?0.76 ?m is measured by spectrophotometer combined with integrating sphere.The incident light angles are 10 °?20°?30 °?40°,the period is 0.8 ?m,the side length of silicon column is 0.4?m,the column height is 0.8 ?m.The test results show when the incident is 30°,the absorptivity is good in the wide band of visible light,up to 84.1%?92.1%,which is basically consistent with the simulation results,and in line with the expected value.The structure is effective to improve the light absorption.