Abstract
Opto-electronic properties of boron phosphide–germanium carbide (BP/GeC), a new van der Walls hetero-bilayer (HBL) with all possible stacking patterns, are studied under the density functional theory originated first-principles. The dynamical and chemical stabilities of the hetero-bilayer are confirmed by phonon spectra and binding energy. Among the dynamically stable HBLs, HBL 1 has the lowest binding energy with the smallest interlayer spacing of about 3.442 Å. Both values and natures (indirect or direct) of the electronic band structure are highly responsive to the stacking patterns. We have found that HBL 1 is indirect, while HBL 2 and HBL 3 become a direct bandgap at the K high symmetry point. All HBLs show type-II band alignment. Both compressive and tensile biaxial strains on the electronic properties of HBLs have been considered. All the HBLs become a direct bandgap for the compressive strain at 4% and 6%. We have also presented the optical property calculations on the HBLs, namely, the complex dielectric function and absorption properties, showing unique optical properties with significant absorption (5 × 105 cm−1 in HBL 2) in the whole solar spectra compared with their comprising monolayers. Moreover, the strain-dependent optical absorption coefficients with varying photon wavelengths are calculated and the maximum value is attained to be about 6.5 × 105 cm−1 in HBL 2 at 4% compressive strain. Consequently, the optoelectronic properties we have explored in our proposed new hetero-bilayer systems can guide the experimental realization of the hetero-bilayers and effective use in the future photovoltaic applications.
Highlights
A new era in the field of material science engineering has been opened up owing to the increasing number of explorations of novel two-dimensional (2D) materials having remarkable optoelectronic properties
For seeking the dynamically stable hetero-bilayer derived from boron phosphide (BP) and germanium carbide (GeC) monolayers, the structural parameters, along with phonon dispersions, are studied here
A first-principles calculation based on density functional theory (DFT) with the van der Waals (vdW) corrected Grimme scheme are involved in this study of strain-mediated electronic and optical properties of novel boron phosphide–germanium carbide (BP/GeC) hetero-bilayers
Summary
A new era in the field of material science engineering has been opened up owing to the increasing number of explorations of novel two-dimensional (2D) materials having remarkable optoelectronic properties. It indicates that the tunability in the bandgap due to stacking patterns, interlayer distances, cross-plane electric field, and biaxial self-induced strain had arisen from the lattice mismatch.[7–14] These scitation.org/journal/adv unique features provoke theoretical and experimental realization of novel 2D layered materials for the ensuing nano-scaled optoelectronic devices. Graphene-like boron phosphide (BP) having promising physical properties shows a lot of attention.[15–19]. It has direct bandgap semiconducting properties with modulating features with the variation of stacking, interlayer distances, and external electric fields.[20,21]. Mogulkoc et al theoretically reported the stacking-dependent modulation in the bandgap for BP/blue phosphorene.[10] the modulation of optical and electronic properties was observed owing to the stacking patterns and cross-plane electric field in the hetero-bilayer material. Another promising material is germanium carbide (GeC), which has a wide electronic bandgap of
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