Photosensitivity of Te-doped silicon photodiodes fabricated using femtosecond laser irradiation.

Microstructured Te-doped silicon is prepared via a femtosecond laser irradiating Si coated with Si-Te bilayer films, and photodiodes are successfully fabricated from this material. The samples are thermally annealed at 773 K for three different time durations. The effects of annealing time on microstructures, infrared absorptance, and photosensitivity of Te-doped silicon are investigated. From the scanning electronic microscope images and the optical absorptance spectra, the results show that the infrared absorptance decreases with the increase of annealing time durations, while the infrared photoresponse follows an opposite tendency. At 1064 nm, the responsivity achieves 2.4836 A/W at -10  V reverse bias for the Te-doped silicon photodiode annealed at 775 K for 2 h, which is higher than that of usual commercial Si photodiodes. These results are important for the fabrication of Te-doped silicon and facilitate its application in infrared detectors.