title: Direct and quasi-direct band gap silicon allotropes with remarkable stability.
abstract: In our present work, five previously proposed sp(3) carbon crystals were suggested as silicon allotropes and their stabilities, electronic and optical properties were investigated using the first-principles method. We find that these allotropes with direct or quasi-direct band gaps in a range of 1.2-1.6 eV are very suitable for applications in thin-film solar cells. They display strong adsorption coefficients in the visible range of sunlight in comparison with diamond silicon. These five silicon allotropes are confirmed to possess positive dynamical stability and remarkable themodynamical stability close to that of diamond silicon. In particular, the direct band gap M585-silicon possessing energy higher than diamond silicon only 25 meV per atom is expected to be experimentally produced for thin-film solar cells.
authors.affiliation: School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China. hechaoyu@xtu.edu.cn jxzhong@xtu.edu.cn.
authors.forename: Chaoyu
authors.initials: C
authors.lastname: He
authors.forename: Chunxiao
authors.initials: C
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Peng
authors.forename: Lijun
authors.initials: L
authors.lastname: Meng
authors.forename: Chao
authors.initials: C
authors.lastname: Tang
authors.forename: Jianxin
authors.initials: J
authors.lastname: Zhong