ИАПУ ДВО РАН

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


2022

Амосов А. В., Ильященко В. М., Кучмижак А. А., Мицай Е. В., Сергеев А. А., Герасименко Андрей Владимирович, Гутаковский Антон Константинович

Applied Surface Science, Q1

Статьи в журналах

7

A.V. Shevlyagin et al. Mg2Si is the new black: Introducing a black silicide with >95% average absorption at 200–1800 nm wavelengths // Applied Surface Science. - 2022. - V. 602. - PP. 154321.

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

https://doi.org/10.1016/j.apsusc.2022.154321

https://www.sciencedirect.com/science/article/pii/S0169433222018554