Electronic and Optical Properties of Novel Phases of Silicon and Silicon-Based Derivatives

ORAL

Abstract

The vast majority of solar cells in the market today are made from crystalline silicon in the diamond-cubic phase. Nonetheless, diamond-cubic Si has an intrinsic disadvantage: it has an indirect band gap with a large energy difference between the direct gap and the indirect gap. In this work, we perform a careful study of the electronic and optical properties of a newly discovered cubic-Si$_{20} $ phase of Si that is found to sport a direct band gap. In addition, other silicon-based derivatives have also been discovered and found to be thermodynamically metastable. We carry out \textit{ab initio} GW and GW-BSE calculations for the quasiparticle excitations and optical spectra, respectively, of these new phases of silicon and silicon-based derivatives. This work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at Lawrence Berkeley National Laboratory's NERSC facility and the NSF through XSEDE resources at NICS.

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Authors

  • Chin Shen Ong

    • University of California at Berkeley

  • Sangkook Choi

    • University of California at Berkeley

  • Steven.G. Louie

    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • UC Berkeley physics/ LBNL MSD
    • Dept. of Physics UC Berkeley and Lawrence Berkeley National Lab
    • University of California - Berkeley, Lawrence Berkeley National Laboratory
    • Physics Department, UC Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley
    • University of California, Berkeley
    • UC Berkeley and Lawrence Berkeley National Laboratory
    • Univ of California - Berkeley
    • Dept. of Physics, University of California, Berkeley and Materials Science Division, Lawrence Berkeley National Laboratory