Fabrication And Anti-Reflection Property Research Of Femtosecond Laser Induced Micro-Structures On Absorbing Layer Of GaAs Solar Cells

As the representative of Ⅲ-Ⅴ semiconductors solar cells, GaAs solar cell shows a relative high photoelectric conversion efficiency as well as good capability of resisting high temperature and irradiation protection compared to Si solar cell. GaAs solar cell is regarded as the main power of satellite spacecraft in the 21 st century and the proportion of its application in the field of space power has exceeded 90% for its advantage of high photoelectric conversion efficiency, high reliability, long life, light weight etc. The photoelectric conversion efficiency is the main performance index of satellite solar cell. The anti-reflection micro-structure can greatly reduce the surface reflection of solar cell which is fabricated by femtosecond laser irradiation. The research object of this paper was GaAs solar cell which is irradiated by fs laser in order to fabricate anti-reflection structure, and the related forming mechanism was also included in the paper. The ultimately purpose of the research is providing a solid and reliable experimental and theoretical basis for improving the GaAs solar cell photoelectric conversion efficiency.This paper studied the effects of different energy parameters and different processing environment in the forming process of the micro-structures on the surface of the GaAs solar cells through the experiments about the fs laser irradiating the GaAs absorption layer. The parameter which can fabricate micro-structure with significant anti-reflection in different environments after SEM, Raman spectra analysis and measurement of the solar spectral reflection of the GaAs solar cell was concluded. And some main results as follows after the research of the strong absorption mechanism of those special structure were investigated.(1) Femtosecond laser system(Legend Elite-1K-HE, Coherent, America) with pulse energy 30μJ was applied to process the GaAs solar cell in air, and we found thatthe uniform rectangular grating micro-structure fabricated on the surface could reduce the average reflection during 300-1000 nm from 33% to 23.6%.(2) Femtosecond laser with pulse energy 15μJ was applied to process the GaAs solar cell and fabricated cone-like micro-structure on the surface which had average reflection with 3% during 300-1200 nm in B while the average reflection of untreated cells during 300-2000 nm is 22.5%. The anti-reflective of this micro-structure is favorable.(3) Femtosecond laser with pulse energy 15μJ was applied to process the GaAs solar cell and fabricated wave-like micro-structure on the surface which had a average reflection with 17.3% during 300-2000 nm in C while the average reflection of untreated cells during 300-2000 nm is 22.5%. This structure was could not be found in other reports.