Mg2Si is the new black: Introducing a black silicide with >95% average absorption at 200–1800 nm wavelengths

Textured silicon surface structures, in particular black (b-Si), open up possibilities for Si-based solar cells and photodetectors to be extremely thin highly sensitive owing perfect light-trapping antireflection properties. However, near-infrared (NIR) performance of bare b-Si is limited by Si band gap 1.12 eV. This work reports a simple method increase NIR absorption vacuo silicidation with magnesium. Obtained Mg2Si/b-Si heterostructure has complex geometry where nanocones are covered Mg2Si shells crowned flake-like hexagons. After growth optimization, cover atop resulted 5-fold lower total reflectivity (3.7%) optical no than 88% over 200–1800 nm spectral range. More importantly, more adjusted match AM-1.5 spectrum theoretically higher photogenerated current density. The maximal advantage demonstrated the region compared full accordance one‘s expectations about NIR-sensitive narrow (0.75 eV) semiconductor high coefficient, which Mg2Si. Results simulation confirmed superiority performance. Therefore, this new wide-band absorber called silicide proved rather competitive alongside state-of-the-art approaches extend blackness.