Elastic and Thermal Properties of Orthorhombic and Tetragonal Phases of Cu 2 ZnSiSe 4 by First Principles Calculations
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LECTRONIC PROPERTIES OF SEMICONDUCTORS
Elastic and Thermal Properties of Orthorhombic and Tetragonal Phases of Cu2ZnSiSe4 by First Principles Calculations Yan Li Gaoa, Wen Shui Guana, and Yu Jing Donga,* a
Xinyang College, School of Science and Technology, Xinyang, 464000 China *e-mail: [email protected] Received June 13, 2019; revised November 11, 2019; accepted May 27, 2020
Abstract—In this paper, based on density functional theory (DFT), the structural, elastic and thermal properties of different structures of the quaternary compound Cu2ZnSiSe4 were studied theoretically. The structural parameters are found to be in good agreement with experimental results. The independent elastic constants are calculated and analyzed, the results show that the structures have mechanical stability. The bulk modulus, Poisson’s ratio, and universal anisotropy index of Cu2ZnSiSe4 are obtained in detail. In order to accurately describe the thermodynamic properties of Cu2ZnSiSe4, the parameters of Debye temperature, thermal expansion coefficient, heat capacity Cv and Cp were analyzed under different pressures and temperatures. Keywords: Cu2ZnSiSe4, density function theory, elastic, thermal DOI: 10.1134/S1063782620100115
1. INTRODUCTION Cu2ZnSiSe4 is an important member of the family of quaternary semiconductor materials. In the past few years, due to its good application prospects in solar cells and other electronic devices [1–8], it has drawn great attention from society and scholars [8–14]. Cu2ZnSiSe4 is the representative of I2–II–IV–VI4 quaternary compound, which is described by orthorhombic Bravais lattice in many papers [15–19]. Considering its band gap characteristics (optical measurements range from 2.1 to 2.3 eV [17–25]), Cu2ZnSiSe4 may also be used as a top cell absorber in a tandem solar cell. The solid solution series Cu2ZnSn1 – xSixSe4 with energy band gap ranging from 2.3 to 1.0 eV, covering most of the solar spectrum, so the quaternary compound Cu2ZnSiSe4 may also be used for solar energy conversion. Recently, many scholars have done a lot of theoretical calculations for the structural types of Cu2ZnSiSe4 (kesterite, stannite, wurtz-stannite) [12, 23, 24]. The first principle is used to calculate the phase stability [12], electronic structure [12, 23], and effective mass of electrons and holes [24]. In addition to the theoretical study of the structure, the infrared absorption bands [18], the Knoop hardness [18], and the vibrational [13], irradiative [19, 25], and electrical properties [17, 18, 26] of Cu2ZnSiSe4 have also been obtained. The sensitivity of materials to temperature and pressure in practical application directly affects the application scope of materials, so it is very import-
ant to study the mechanical stability of materials and the influence of temperature and pressure on the thermal properties of materials. The structural types of Cu2ZnSiSe4 are kesterite type (KS, space group I4), stannite type (ST, space group I42m) and wurtz-stannite type (WST, space group Pmn21). In this paper, the structu
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