Fabrication and infrared absorption of tellurium doped silicon via femtosecond-laser irradiation

摘要

Doping silicon with chalcogens (S, Se, Te) via femtosecond-laser irradiation lead to increase the absorptance of Si in both visible and infrared region, so chalcogens doped silicon have great potential for use in Si-based optoelectronic devices. Tellurium doped silicon was fabricated by femtosecond-laser irradiation of Si with Si/Te bilayer films. The influence of distance between the sample surface and the laser focus in the process of fabricating micro-structured Si was studied. The results show that the sample surface cannot be located in focal plane, nor is far from the focal plane, suitable distance is necessary to produce regular columnar structure. And the surface structure of doped silicon is vitally important to high absorptance. In addition, we report the dependence of surface morphology and optical properties on scanning speed. The absorptance increases over the entire wavelength as the scanning speed decreases.