Tuning the electronic structure and optical properties of β-Te/g-SiC and β-Te/MoS2 van der Waals heterostructure

beta-tellurene, one of the allotropes of the recently discovered two-dimensional (2D) forms of tellurium, is a semiconductor of excellent properties. By forming van der Waals heterostructures (vdWHs) with other 2D materials, it can be potentially useful for various fields. However, the properties of tellurene vdWHs had seldom been exploited yet. This work studies the properties of vdWHs formed by tellurene with monolayer graphitic SiC (g-SiC) and MoS2 using first-principles calculation. First of all, the electronic structures are investigated. The beta-Te/g-SiC vdWH shows a weak type-II band alignment with a direct bandgap of 1.0988 eV which can be potentially useful for photocatalytic water decomposition. Whereas the beta-Te/MoS2 vdWH shows a type-I band alignment with a bandgap of 0.6261 eV which can be potentially useful for electronic devices. Moreover, inplane uniaxial strain on X direction within the range of -9%-9% is applied to the heterostructures to explore the tunability of their electronic structures. The results show the bandgap can be tuned from 1.24 eV to 0.83 eV for the beta-Te/g-SiC vdWH, and 0.82 eV-0.07 eV for the beta-Te/MoS2 vdWH, respectively. Lastly, the variation of optical properties under external strain is studied which shows a maximum absorption coefficient of 10(6) cm(-1) at the external strain of 9%. This work shows that the two heterostructures possess properties that are both promising and tunable, and the results can be helpful for designing 2D electronic and photoelectronic devices.