Designing a Novel Trigonal Silicon Material: First-Principles Calculations

Q. Fana, b, Y. Lia, R. Yanga, X. Yuc, S. Yund aCollege of Information and Control Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China bShaanxi Key Laboratory of Nano Materials and Technology, Xi'an 710055, China cDepartment of Mechanical and Electrical Engineering, Hetao College, Bayannur, Inner Mongolia 015000, China dFunctional Materials Laboratory (FML), School of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China

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As the cornerstone of many high-technological things, semiconductor silicon material has been widely studied in the past few decades. The present study introduces a new type of silicon allotrope named tri-Si18, belonging to the space group P3221. Based on first-principles calculation, its structure characteristics, stability, electronic properties, and thermal conductivity are systematically investigated and analyzed. The elastic constant and phonon spectrum of tri-Si18 demonstrate its mechanics and dynamics stability. The relative enthalpy of tri-Si18 is only 0.089 eV/atom, which is more favorable than that of most silicon allotropes. Furthermore, the tri-Si18 exhibits elastic anisotropy, particularly in the direction of [100], [010], [110], and [111]. In addition, tri-Si18 is a semiconductor material with an indirect band gap of 1.770 eV. More interestingly, the minimum thermal conductivity of tri-Si18 reached 1.10 W/(K cm), which is greater than that of I-4 Si, C2/m-20 Si, P2221 Si, Amm2 Si, Pm-3m Si, and Si64. It is suggested that if tri-Si18 is used to make microelectronic devices, they may have better heat dissipation capacity. Due to its lower relative enthalpy and taller minimum thermal conductivity, tri-Si18 can be used in a diverse variety of optoelectronic materials and in electronic device fabrication.

DOI:10.12693/APhysPolA.145.273 topics: silicon, first-principles calculations, indirect band gap, thermal conductivity