关键词: 2H-MoTe₂, 光电器件, 光电效应, 第一性原理, 能带结构, 空位缺陷

Abstract: MoTe₂ has been widely studied due to its special stacking mode and rich phase structure, especially the suitable band gap which makes it have a promising application in the field of optoelectronic devices. Based on the non-equilibrium Green’s function-density functional theory, the influence of different atomic vacancy defects on the photogalvanic effect of monolayer 2H-MoTe₂ was studied by the first-principles calculation method. The results show that the photocurrent function of 2H-MoTe₂ devices with different vacancies is consistent with the phenomenological theory. In the photon energy range from 1.0 eV to 2.8 eV, 2Te vacancy significantly improves the photocurrent of 2H-MoTe₂, especially when the photon energy is 2.6 eV, the maximum photocurrent of all devices is obtained. With the energy band structure, it is found that different atomic vacancy defects lead to the shift of the valence band to the high energy level and the conduction band to the low energy level, which reduces the band gap between the four devices and conducive to the transition of electrons from the valence band to the conduction band to form photocurrent under the irradiation of linearly polarized light. It is found that the monolayer 2H-MoTe₂ of 1Te vacancy and Mo vacancy has a similar energy band structure far away from the Fermi level, which leads to the same change trend of the device photocurrent when the photon energy is greater than 1.6 eV. These results can be used to guide the design of MoTe₂ optoelectronic devices.

Key words: 2H-MoTe₂, optoelectronic device, photogalvanic effect, first-principle, band structure, vacancy defect