Mohanta Manish Kumar, De Sarkar Abir
Institute of Nano Science and Technology, Phase 10, Sector 64, Mohali, Punjab - 160062, India.
Nanoscale. 2020 Nov 28;12(44):22645-22657. doi: 10.1039/d0nr07000a. Epub 2020 Nov 6.
In this work, we explored the interfacial two-dimensional (2D) physics and significant advancements in the application prospects of MoSSe monolayer when it is combined with a boron pnictide (BP, BAs) monolayer in a van der Waals heterostructure (vdWH) setup. The constructed vdWHs were found to be mechanically and dynamically stable, and they form type-II p-n heterojunctions. Thus, the photogenerated electron-hole pairs are spatially separated. In the BX/MoSSe vdWHs, the BX monolayer serves as excellent donor material for MoSSe, having an ideal donor band gap of ∼1.3 eV. The small value of the conduction band offset (CBO) between the individual monolayers in the vdWHs makes it an excellent candidate for solar energy harvesting in excitonic solar cells, where the power conversion efficiencies were calculated to be 22.97% (BP/MoSSe) and 20.86% (BAs/MoSSe). Also, more than four-fold enhancement in the out-of-plane piezoelectric coefficient (d) was observed in the MoSSe-based vdWH relative to that in the MoS-based vdWH owing to the intrinsic built-in vertical electric field in MoSSe. This is consistent with the out-of-plane piezoelectricity brought about by the alteration in symmetry at the metal-semiconductor Schottky junction, which has been observed experimentally [M.-M. Yang, Z.-D. Luo, Z. Mi, J. Zhao, S. P. E and M. Alexe, Nature, 2020, 584, 377-381]. The results obtained in this work provide useful insights into the design of nanomaterials for future applications in nano-optoelectronics, more efficient excitonic solar cells, and nanoelectromechanical systems (NEMS). Furthermore, this work demonstrates outstanding potential for the application of these vdWHs in superfast electronics, including low-power digital data storage and memory devices, where the tunnel current between the source and drain is effectively tunable using a normal electric field of small magnitude serving as the gate voltage.
在这项工作中，我们探索了界面二维（2D）物理以及在范德华异质结构（vdWH）设置中，二硫化钼硒（MoSSe）单层与硼磷化物（BP，BAs）单层结合时其应用前景的重大进展。所构建的vdWH被发现具有机械和动态稳定性，并且它们形成II型p-n异质结。因此，光生电子-空穴对在空间上被分离。在BX/MoSSe vdWH中，BX单层作为MoSSe的优良供体材料，具有约1.3 eV的理想供体带隙。vdWH中各单层之间的导带偏移（CBO）值较小，这使其成为激子太阳能电池中太阳能收集的优良候选材料，其中计算得出的功率转换效率分别为22.97%（BP/MoSSe）和20.86%（BAs/MoSSe）。此外，由于MoSSe中固有的内置垂直电场，相对于基于MoS的vdWH，在基于MoSSe的vdWH中观察到面外压电系数（d）增强了四倍以上。这与在金属-半导体肖特基结处对称性改变所导致的面外压电性一致，这已通过实验观察到[杨美华，罗振东，米泽，赵军，S.P.E和M.阿列克谢，《自然》，2020，584，377 - 381]。这项工作所获得的结果为未来纳米光电子学、更高效的激子太阳能电池和纳米机电系统（NEMS）中的纳米材料设计提供了有用的见解。此外，这项工作展示了这些vdWH在超快电子学中的杰出应用潜力，包括低功耗数字数据存储和存储设备，其中源极和漏极之间的隧道电流可通过用作栅极电压的小幅度正常电场有效地进行调节。
