The published papers are listed below. 1. WS2/MoS2. Figure 5b. The band alignment at the K-point for the WS2/MoS2 heterostructure. Nano Letters, 2014, 14, ...
Band alignment of 2D materials based heterostructure When two semiconductors form heterostructure, the Fermi levels are the same in equilibrium. So the band alignment of the heterostructure strongly affect by the doping level of each semiconductor, for example, PN junction used for diodes. Recently, I find that there are so many papers shown band alignment of heterostructures without considering the Fermi level of constituted semiconductor. They used electron affinity level to construct their band alignments and claimed that it meet Anderson rule (IEEE J. Res. Dev., 1960, 4, 283). However, Anderson has said in that paper that the band alignment in figure 1 “is not the band picture at equilibrium”, the equilibrium band alignment of the heterostructure should including the consideration of the Fermi level of each semiconductors (Figure 2 and 3).
Figure 1 in Anderson’s paper.
Figure 2 and 3 in Anderson’s paper. The published papers are listed below. 1. WS2/MoS2
Figure 5b. The band alignment at the K-point for the WS2/MoS2 heterostructure. Nano Letters, 2014, 14, 3185.
Figure 1a. Schematic of the theoretically predicted band alignment of a MoS2/WS2 heterostructure, which forms a type II heterojunction. Optical excitation of the MoS2 A-exciton will lead to layerseparated electron and hole carriers. Nature Nanotechnology, 2014, 9, 682.
Figure 2d. Schematic illustration for the bandstructure alignment of the heterostructure. “Theorectical calculations have indicated that the band structure of epitaxial MoS2/WS2 heterostructures at the K-point in the Brillouin zone is approximately a simple superposition of the states of monolayer MoS2 and WS2.” Nano Letters, 2015, 15, 486. Theorectical calculations only consider the perfect situation. In reality, the MoS2 and WS2 monolayer obtained showing n-type behavior, which suggests the Fermi level of each one locates close to the valance band edge. The Fermi level of the two is same when forming heterostructure. The difference of the Fermi level of monolayer MoS2 and WS2 determines the real band alignment, which also leads to the formation of band bending.
2. MoS2/SnS2
Figure 3h. Calculated band alignment for SnS2 and MoS2 monolayers by VASP. Advanced Electronic Materials, 2016, 2, 1600298. 3. MoS2/CdS
Figure 4g. Band gap schematic of CdS/MoS2 heterostructure photodetector under illumination. Advanced Functional Materials, 2016, 26, 2648. 4. WS2/CH3NH3PbI3
Figure 1e. Band structures of WS2 and perovskite in the hybrid bilayer. “As a result of the difference between their Fermi levels, photogenerated charges are separated, which reduces the charge recombination and enhances the photodetector performance.” This right. But the band alignment do not show the band bending and Fermi level. Advanced Materials, 2016, 28, 3683. 5. MoS2/CH3NH3PbI3
Figure 1a. Energy-band diagrams of the perovskite/MoS2 hybrid structure. Advanced Materials, 2016, 28, 7799.
