Gao Chan, Yang Xiaoyong, Jiang Ming, Chen Lixin, Chen Zhiwen, Singh Chandra Veer
Department of Materials Science and Engineering, University of Toronto, Toronto, ON M5S 3E4, Canada.
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
Phys Chem Chem Phys. 2022 Feb 16;24(7):4653-4665. doi: 10.1039/d1cp05847a.
Monolayer transition metal dichalcogenide (TMD) alloys with tunable direct band gaps have promising applications in nanoelectronics and optoelectronics. The composition-dependent band gaps of ternary, quaternary and quinary monolayer TMD alloys have been systematically studied combining density functional theory and machine learning models in the present study. The excellent agreement between the DFT-calculated band gaps and the ML-predicted values for the training, validation and test datasets demonstrates the accuracy of our machine learning based on a neural network model. It is found that the band gap bowing parameter is closely related to the difference between the band gaps of the endpoint material compositions of the monolayer TMD alloy and increases with increasing band gap difference. The band gap bowing effects of monolayer TMD alloys obtained by mixing different transition metals are attributed to the conduction band minimum positions, while those of monolayer TMD alloys obtained by mixing different chalcogen atoms are dominated by the valence band maximum positions. This study shows that monolayer TMD alloys with tunable direct band gaps can provide new opportunities for band gap engineering, as well as electronic and optoelectronic applications.
具有可调直接带隙的单层过渡金属二硫属化物（TMD）合金在纳米电子学和光电子学中具有广阔的应用前景。在本研究中，结合密度泛函理论和机器学习模型，系统地研究了三元、四元和五元单层TMD合金的成分依赖带隙。训练、验证和测试数据集的密度泛函理论计算带隙与机器学习预测值之间的良好一致性证明了我们基于神经网络模型的机器学习的准确性。研究发现，带隙弯曲参数与单层TMD合金端点材料成分的带隙差异密切相关，并随带隙差异的增加而增大。通过混合不同过渡金属获得的单层TMD合金的带隙弯曲效应归因于导带最小位置，而通过混合不同硫属原子获得的单层TMD合金的带隙弯曲效应则由价带最大位置主导。这项研究表明，具有可调直接带隙的单层TMD合金可以为带隙工程以及电子和光电子应用提供新的机会。
