Amorphous silicon hexaboride: a first-principles study

ABSTRACT

We report for the first time the atomic structure, electronic structure and mechanical properties of amorphous silicon hexaboride (a-SiB₆) based on first-principles molecular dynamics simulation. The a-SiB₆ model is generated from the melt and predominantly consists of pentagonal pyramid-like configurations and B₁₂ icosahedral molecules, similar to what has been observed in most boron-rich materials. The mean coordination number of B and Si atoms are 5.47 and 4.55, respectively. The model shows a semiconducting behaviour with a theoretical bandgap energy of 0.3 eV. The conduction tail states are found to be highly localised and hence the n-type doping is suggested to be more difficult than the p-type doping for a-SiB₆. The bulk modulus and Vickers hardness of a-SiB₆ are estimated to be about 118 and 13–17 GPa, respectively.

KEYWORDS:

• Ab initio
• amorphous materials
• disordered systems

Acknowledgements

The simulations were run on the TÜBİTAK ULAKBİM, High Performance and Grid Computing Center (TRUBA resources).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) under grant number 117M372.