Abstract
First-principle calculations based on the density functional theory (DFT) are implemented to study the structural and electronic properties of the SiS2/WSe2 hetero-bilayers. It is found that the AB-2 stacking model is most stable among all the six SiS2/WSe2 heterostructures considered in this work. The AB-2 stacking SiS2/WSe2 hetero-bilayer possesses a type-II band alignment with a narrow indirect band gap (0.154 eV and 0.738 eV obtained by GGA-PBE and HSE06, respectively), which can effectively separate the photogenerated electron–hole pairs and prevent the recombination of the electron–hole pairs. Our results revealed that the band gap can be tuned effectively within the range of elastic deformation (biaxial strain range from −7% to 7%) while maintaining the type-II band alignment. Furthermore, due to the effective regulation of interlayer charge transfer, the band gap along with the band offset of the SiS2/WSe2 heterostructure can also be modulated effectively by applying a vertical external electric field. Our results offer interesting alternatives for the engineering of two-dimensional material-based optoelectronic nanodevices.
Highlights
In the past two decades, the emergence of two-dimensional layered materials [1,2,3,4] has attracted tremendous attention of researchers due to their novel electronic properties, such as high carrier mobility [5,6], high thermal conductivity [7] and excellent on/off ratio [8], which ensure their potential application prospects in the field of photoemission, photodetection and field effect transistors (FETs)
Our results show that the most stable SiS2/WSe2 hetero-bilayer possesses the type-II band alignment with a narrow band gap, which contributes to the separation of electron–hole pairs
The structural and electronic properties of the SiS2/WSe2 hetero-bilayers are investigated in detail through first principles calculations
Summary
In the past two decades, the emergence of two-dimensional layered materials [1,2,3,4] has attracted tremendous attention of researchers due to their novel electronic properties, such as high carrier mobility [5,6], high thermal conductivity [7] and excellent on/off ratio [8], which ensure their potential application prospects in the field of photoemission, photodetection and field effect transistors (FETs). Graphene, silicene and germanene, as the most promising materials, all have linear dispersion at the Fermi level at the K-point in the Brillouin zone. One of the key factors for the development of 2D materials is dependent on its tunable band gap [11,12]. Being a gapless semiconductor, graphene, silicene and germanene cannot be directly used in electronic optoelectronic devices [13,14]. If we introduce a hetero-bilayer system by stacking two single-layer materials vertically, the tunable band gaps could be realized by employing in-plane biaxial stress or changing the interlayer distance [15,16,17,18]
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