Prediction of a new direct-gap silicon phase: T36 silicon

Publication date: Available online 26 August 2019Source: Physics Letters AAuthor(s): Chun-Xiang Zhao, Yang Huang, Jia-Qi Wang, Chun-Yao Niu, Yu JiaAbstractElemental silicon plays an extremely important role in technologically relevant fields. Owing to its abundance, silicon is the preferred solar-cell materials in spite of the fact that many silicon allotropes have indirect band gaps. Looking for silicon materials with direct band gap is still a significant field in material science. Here, we propose a new silicon allotrope possessing a tetragonal cell with 36 silicon atoms (termed as T36 silicon), which displays P42nmc symmetry. By first-principles calculations, we have systematically studied the structural stabilities, electronic and optical properties of this novel silicon. Our calculations reveal that T36 silicon is thermally, dynamically and mechanically stable, and is a semiconductor with direct band gap of 0.591 eV. The absorption coefficients of T36 silicon in the visible light range are significantly enhanced compared with diamond-Si. The T36 silicon can be expected to be useful for practical applications in optoelectronics, photo catalysts, and so on.
Source: Physics Letters A - Category: Physics Source Type: research