Enhanced Wide-band Infrared Absorptivity of Black Silicon

In the present work, we report, on the exceptionally high absorptivity of Black Silicon (BSi) in the spectral range of thermal radiation, which can be instrumental for various thermal radiation related applications. Having fabricated two wafers of BSi having n-type low and high doping, we have found experimentally that for highly doped BSi, a high absorptivity is observed till 15 µm which has also been compared with similarly doped Flat Si (FSi) samples. However, beyond 15 µm, the absorptivity of highly doped BSi sample decreases. Subsequent processing of SEM images reveals that these noteworthy radiative properties can probably be attributed to particular morphological features of heavily doped BSi at the nanoscale. These features are quantified through statistical image processing. Reported results pave the way to highly integrated and effective infrared sources using Black Silicon.