| Because of the band gap?1.12 e V?,silicon cannot absorb near-infrared light of wavelength?=1.1–2.5?m in the solar spectrum.The energy in this part of the solar spectrum occupies about 30%of the total solar energy.Therefore,black silicon fabricated by hyperdoping of sulfur deep-level impurities is used to regulate the energy band structure of silicon to form sub-band gaps,thereby changing the spectral absorption range of silicon.If the strong absorption of full-solar spectrum??=0.25–2.5?m?by the black silicon material can effectively form photogenerated charge carriers,it is expected to exceed the conversion efficiency limit of silicon-based solar cells.In addition,black silicon can also be used as an excellent material for room-temperature infrared detector.In this thesis,sulfur deep-level impurity sources were provided by SF6background atmosphere and Si-S-Si multilayer films,respectively.Black silicon materials were successfully prepared by nanosecond?ns?-pulsed laser irradiation.The microstructure,composition,optical properties,and electrical properties of the black silicon materials prepared by the two ways were characterized by various analysis methods.In addition,since the thermal annealing is a conventional process for semiconductor optoelectronic devices,the effect of thermal annealing on the properties of the black silicon material was also studied.The research results show that compared with the fabrication method of femtosecond?fs?-pulsed laser,the black silicon material prepared by the ns-pulsed laser has good crystallinity,the impurity concentration with the order of 1020 cm-3,and good full-solar spectrum absorption and electrical properties,including high carrier concentration,high Hall mobility,and low sheet resistance.Furthermore,compared with the fabrication process of the SF6 atmosphere,the process of Si–S–Si multilayer film is simpler,the cost lower,and thus more suitable for preparing a large area of black silicon for the device. |
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