A Novel Silicon Allotrope in the Monoclinic Phase.

Chaogang Bai,Yuqian Liu,Changchun Chai,Qingyang Fan,Yintang Yang

doi:10.3390/ma10040441

Abstract

This paper describes a new silicon allotrope in the P2/m space group found by first-principles calculations using the Cambridge Serial Total Energy Package (CASTEP) plane-wave code. The examined P2/m-Si belongs to the monoclinic crystal system. P2/m-Si is an indirect band-gap semiconductor with a band gap of 1.51 eV, as determined using the HSE06 hybrid functional. The elastic constants, phonon spectra and enthalpy indicate that P2/m-Si is mechanically, dynamically, and thermodynamically stable. P2/m-Si is a low-density (2.19 g/cm3) silicon allotrope. The value of B/G is less than 1.75, which indicates that the new allotrope is brittle. It is shown that the difference in the elastic anisotropy along different orientations is greater than that in other phases. Finally, to understand the thermodynamic properties of P2/m-Si, the thermal expansion coefficient α, the Debye temperature ΘD, and the heat capacities CP and CV are also investigated in detail.

Highlights

Silicon plays an extremely important role in semiconductor materials [1,2,3,4,5,6,7,8,9]
Monocrystalline, polycrystalline, and amorphous silicon are types of silicon materials used in solar cells
Due to the existing processing conditions, diamond silicon is the primary material used in the solar cell market

Summary

Introduction

Silicon plays an extremely important role in semiconductor materials [1,2,3,4,5,6,7,8,9]. Silicon is one of the most important photovoltaic (PV) materials in the solar cell industry [2,10]. Due to the existing processing conditions, diamond silicon is the primary material used in the solar cell market. Diamond silicon (space group: Fd-3m) is not a direct band-gap semiconductor, and there is a large energy difference (2.3 eV) between the indirect band gap and the direct band gap, which reduces its solar energy absorption efficiency [10,11]. Researchers continue to search for silicon allotropes with direct band gap or better physical properties

Methods

Results

Conclusion