BC8 Silicon (Si-III) is a Narrow-Gap Semiconductor
- Carnegie Inst. of Washington, Washington, DC (United States)
- Univ. of South Florida, Tampa, FL (United States)
- Sorbonne Univ., Paris (France)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
Large-volume, phase-pure synthesis of BC8 silicon ($$Ia\bar{3}$$, cI16) has allowed bulk measurements of optical, electronic, and thermal properties. Unlike previous reports that conclude BC8-Si is semimetallic, we demonstrate that this phase is a direct band gap semiconductor with a very small energy gap and moderate carrier concentration and mobility at room temperature, based on far- and midinfrared optical spectroscopy, temperature-dependent electrical conductivity, Seebeck and heat capacity measurements. Samples exhibit a plasma wavelength near 11 μm, indicating potential for infrared plasmonic applications. Thermal conductivity is reduced by 1–2 orders of magnitude depending on temperature as compared with the diamond cubic (DC-Si) phase. The electronic structure and dielectric properties can be reproduced by first-principles calculations with hybrid functionals after adjusting the level of exact Hartree–Fock (HF) exchange mixing. These results clarify existing limited and controversial experimental data sets and ab initio calculations.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research in Extreme Environments (EFree)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0001057; FG02-04ER46145
- OSTI ID:
- 1388062
- Alternate ID(s):
- OSTI ID: 1349707
- Report Number(s):
- BNL-114579-2017-JA; PRLTAO
- Journal Information:
- Physical Review Letters, Vol. 118, Issue 14; Related Information: EFree partners with Carnegie Institution of Washington (lead); California Institute of Technology; Colorado School of Mines; Cornell University; Lehigh University; Pennsylvania State University; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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