研究目的
To explore the physical mechanisms of the phosphorene/SnS2 (SnSe2) vdWHs and related tunable characteristics under an electric field.
研究成果
This work theoretically demonstrates type-III (broken-gap) vdWHs, phosphorene/SnS2 and phosphorene/SnSe2, using vdW-corrected DFT calculations. The BTBT transport mechanism of the phosphorene/SnS2 (SnSe2) vdWHs implies their applications in TFETs. Moreover, a positive electric field can enlarge the tunneling window and increase the tunneling probability, while a negative electric field can induce multiple-band-alignment transformation (type I, type II, and type III) in the two vdWHs. In addition, NDR effects can be found in the I-V curves of phosphorene/SnS2 (SnSe2) vdWHs-based devices, verifying the BTBT transport mechanism.
研究不足
The model has some limitations for practical device simulation. For practical devices, phosphorene/SnSe2 heterojunctions can be fabricated with the mechanical transfer method, and the overlap region of the two components can be formed. Therefore, to simulate the properties of practical devices, the model of semi-infinite heterojunctions and the method suggested by Refs. [49–52] are closer to the experimental measurements.
1：Experimental Design and Method Selection:
The calculations for the electronic structures are performed using the density functional theory (DFT)-based first-principles methods, implemented in the Vienna ab initio simulation package (VASP). The Perdew-Burke-Ernzerhof (PBE) functional of the generalized gradient approximation (GGA) is used to describe the exchange correlation potential. The DFT calculations with dispersion corrections (DFT-D2) proposed by Grimme is adopted to describe the vdW interaction in the vdWHs. The transport properties are calculated using the Atomistix ToolKit (ATK) package based on the density functional theory and nonequilibrium Green’s function (NEGF) method.
2：Sample Selection and Data Sources:
The phosphorene/SnS2 (SnSe2) vdWHs are constructed by stacking phosphorene and SnS2 (SnSe2) monolayers along the c direction.
3：List of Experimental Equipment and Materials:
VASP and ATK packages are used for calculations.
4：Experimental Procedures and Operational Workflow:
The structures are fully relaxed until the force on each atom is less than 0.01 eV/?, and the convergence criterion of total energy is chosen to be 10?5 eV. The k-point sampling using the Monkhorst-Pack scheme is set to be a 7 × 9 × 1 mesh for structural relaxations.
5：01 eV/?, and the convergence criterion of total energy is chosen to be 10?5 eV. The k-point sampling using the Monkhorst-Pack scheme is set to be a 7 × 9 × 1 mesh for structural relaxations.
Data Analysis Methods:
5. Data Analysis Methods: The transport properties are analyzed using the NEGF method.
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