Silicon-compatible Mg2Si/Si n-p photodiodes with high room temperature infrared responsivity

Abstract

For the full benefit of the silicon chip industry and to further extend the photoresponse cut-off wavelength of the current Si photodetectors beyond 1100 nm, high-performance silicon-compatible Mg2Si/Si n-p photodiodes are constructed on the bulk silicon wafer by magnetron sputtering and post-annealing sequential processes. The results show that the annealing period appreciably affects microstructure, crystallite size, and roughness of the Mg2Si film sputtered on glass substrates and silicon wafers. Meanwhile, the fabricated Mg2Si/Si n-p photodiodes demonstrate clear rectifying behavior and evident spectral response characteristics in the wavelength domain from 0.8 to 1.35 μm, with a maximum room temperature zero-bias response of 0.1, 0.15, 0.86, and 0.47 A/W at 1.05 μm for the annealing periods of 10, 20, 40, and 60 min, respectively. The photoresponse cut-off wavelength of the fabricated Mg2Si/Si n-p photodiodes is 1.35 μm; however, the photosensitive cut-off of the commercially available Hamamatsu Si photodiode is 1.25 μm. The fabricated Mg2Si/Si n-p photodiodes at RTA period of 40 min reveal spectral response of longer cut-off wavelength and higher intensity near the photon energy threshold compared to the Hamamatsu Si photodiode. In this context, the fabricated photodiodes in this study offer huge potentials to develop high-performance silicon-compatible photodiodes for efficiently sensing the infrared light in the wavelength domain from 0.8 to 1.35 μm.