First principles investigation of optoelectronic properties of ZnXP2 (X = Si, Ge) lattice matched with silicon for tandem solar cells applications using the mBJ exchange potential
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Date
2018
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Publisher
Université de M'sila
Abstract
II-IV-V2 materials are attractive compounds for optoelectronic, photonic and photovoltaic
applications due to their valuable ternary chemistry. A primary technological challenge
in photovoltaics is to find and develop a lattice matched efficient material to be used
in combination with silicon for tandem solar cells. ZnSiP2 and ZnGeP2 chalcopyrites are
promising semiconductors that could satisfy these criteria. Particularly, ZnSiP2 is known to
have bandgap energy of
∼2 eV and a lattice mismatch with silicon of 0.5%. In this work, the
first principle calculations have been performed to investigate the structural, electronic and
optical properties of ZnSiP2 and ZnGeP2 in chalcopyrite structure within the Full Potential-
Linearized Augmented Plane Wave (FP-LAPW) method based on the Density Functional
Theory (DFT) as implemented in WIEN2K code. The local Density approximation (LDA) of
Perdew and Wang was used as exchange-correlation potential to calculate the structural
proprieties. Furthermore, the recently modified Becke-Johnson (mBJ) functional of Tran
and Blaha was also employed to compute the electronic and optical properties in order to
get best values of the band gap energy and some better degree of precision. The complex
dielectric function, the complex refractive index, reflectivity, absorption coefficient, and the
optical conductivity were calculated to illustrate the linear optical properties of both compounds
ZnSiP2 and ZnGeP2. At last, the obtained results indicate that ZnSiP2 and ZnGeP2
are attractive materials in optoelectronic devices especially as a lattice matched material
with silicon for tandem solar cells applications.
Description
Keywords
FP-LAPW mBJ Chalcopyrite Electronic band structure Linear optical properties