Effects of Doping on the Morphology and Infrared Radiative Properties of Black Silicon

For the first time, we show that the density of nanostructures on Black Silicon obtained by wafer-level cryogenic plasma processing increases with a high level of doping, extending the spectral range of its very high absorptivity from near-infrared to far-infrared. We have found experimentally and confirmed by simulations that, for highly doped Black Silicon, a high absorptivity is observed till 15 μm. Subsequent processing of SEM images reveals that these noteworthy radiative properties are probably due to particular morphological features of heavily doped Black Silicon at the nano-scale. These features are quantified through statistical image processing. Reported results pave the way to highly integrated and effective infrared sources using Black Silicon.