First-principle calculations of the electronic, optical and elastic properties of ZnSiP 2 semiconductor V. Kumar ⇑ , S.K. Tripathy Department of Electronics Engineering, Indian School of Mines, Dhanbad 826 004, India article info Article history: Received 25 May 2013 Received in revised form 1 August 2013 Accepted 3 August 2013 Available online 14 August 2013 Keywords: ZnSiP 2 semiconductor DFT calculation Electronic structure Optical properties Elastic constants abstract The plane wave pseudo-potential method within density functional theory (DFT) has been used to inves- tigate the structural, electronic, optical and elastic properties of ZnSiP 2 chalcopyrite semiconductor. The lattice constants are calculated from the optimized unit cells and compare with the experimental value. The band structure, total density of states (TDOS) and partial density of states (PDOS) have been dis- cussed. The energy gap has been calculated along the U direction found to be 1.383 eV, which shows that ZnSiP 2 is pseudo-direct in nature. We have also analyzed the frequency dependent dielectric constant e(x) and calculated the birefringence (Dn). The optical properties under three different hydrostatic pres- sures of 0 GPa, 10 GPa and 20 GPa have been described for the first time in the energy range 0–20 eV. The values of bulk modulus (B), pressure derivative of bulk modulus (B / ), elastic constants (C ij ), Young’s mod- ulus (Y), anisotropic factor (A) and Poisson’s ratio (m) have been calculated. The calculated values of all above parameters are compared with the available experimental values and the values reported by dif- ferent workers. A fairly good agreement has been found between them. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Recently, an increasing attention has been given towards the study of ZnSiP 2 ternary chalcopyrite semiconductor because of its interesting structural, electronic, optical and elastic properties [1]. The chalcopyrite semiconductors crystallize in the tetragonal structure at ambient condition with space group (I 4  2d) and has four formula units per unit cell, which is a ternary analog of well known zincblende III–V binary semiconductors. ZnSiP 2 is an important material of II–IV–V 2 group and possesses a high nonlin- ear susceptibility with adequate bifringence, which makes it very useful for an efficient second harmonic generation and phase matching. Its application has been realized for high power optical frequency conversion in the near and mid-infrared regions. It has great promise for various applications in the fields of quantum electronics, spintronics and optoelectronics [2]. There have been various experimental and theoretical ap- proaches to explain the different properties of ZnSiP 2 semiconduc- tor [1–6]. The phonon lines in this semiconductor have been observed by infrared reflectivity and Raman measurements [2], and later on analyzed by different workers using Group Theory for mode prediction [3,4]. Shirakata et al. [5] have discussed the hydrostatic-pressure dependence of the first-order Raman spectra of ZnSiP 2 crystal and the Gruneisen parameter of each Raman mode. The crystal structure and phonon structure analysis have been carried out using X-ray diffraction and Raman Spectroscopy by Pena-Pedraza et al. [6]. The full potential linear augmented plane wave plus local orbit (FP-LAPW+lo) method has been used to find out the reflectivity spectra of ZnXP 2 (X = Si, Ge, Sn) semicon- ductors [7], electronic properties of ASiAs 2 (A = Zn, Cd) compounds [8], and the effect of cations on band structure of ZnGeAs 2 pnic- tides [9]. First principle calculations have been carried out to de- scribe the magnetic properties of Mn-doped II–IV–V 2 semiconductors [10] and electronic properties of II–IV–V 2 (II = Be, Mg, Zn, Cd; IV = Si, Ge, Sn; V = P, As) semiconductors [11,12]. Den- sity functional theory (DFT) has been used by several researchers to explain the structural, electronic and optical properties of I– III–VI 2 and II–IV–V 2 groups of semiconductors [13–15]. The elect- roreflectance studies of ZnSiP 2 have been discussed by Shay et al. [16]. Kumar et al. [17–20] have explained the various electronic [17], elastic [18], thermal [19] and nonlinear [20] properties of ter- nary chalcopyrites using plasma oscillations theory of solids. Other workers [21,22] have proposed various empirical relations to cal- culate the elastic constants, energy gaps and electronic polarizabil- ity of different binary and ternary semiconductors. Arab et al. [23] have investigated the structural, elastic and electronic properties of ZnSiP 2 semiconductor under high pressure and found that the structure of ZnSiP 2 is stable up to 35 GPa. So far, no study on opti- cal properties has been carried out under different pressure. There- fore, it has been thought of interest to study the various optical properties of ZnSiP 2 under different hydrostatic pressures in 0925-8388/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jallcom.2013.08.025 ⇑ Corresponding author. Tel.: +91 9431122030. E-mail address: vkumar52@hotmail.com (V. Kumar). Journal of Alloys and Compounds 582 (2014) 101–107 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom