Insights into controllable electronic properties of 2D type-II Twin-Graphene/g-C3N4 and type-I Twin-Graphene/hBN vertical heterojunctions via external electric field and strain engineering

Twin-graphene (Twin-G), an accessible carbon allotrope composed of sp(2) hybridized carbon atoms, has attracted considerable interest due to its intrinsic bandgap and tunable electronic properties. This work evaluates the near-edge electronic structures and the carrier mobility of the Twin-G/g-C3N4 and Twin-G/hBN vdW heterojunctions employing the first-principles calculations. The results demonstrate that Twin-G/g-C3N4 retains a staggered type-II alignment, which may benefit the highly-efficient photogenerated carrier separation. Whereas the Twin-G/hBN exhibits type-I alignment. An external electrical field induces a semiconductor-to-metal and indirect-to-direct gap transition in Twin-G/g-C3N4 heterostructure. The type-II-to-type-I transition in Twin-G/g-C(3)N(4)under tensile strain can be understood from the near-gap wave functions morphology. G-C3N4 substrate has a more significant effect to enhance the carrier mobility of Twin-G. The electron mobility along the zigzag-direction in Twin-G/g-C3N4 is similar to 1751 cm(2)V(-1)s(-1), far surpassing that of Twin-G monolayer. These results open up promising opportunities for the development of optoelectronic devices based on the Twin-G heterostructures. (c) 2022 Published by Elsevier B.V.

Automated summary

This work evaluates the near-edge electronic structures and carrier mobility of Twin-G/g-C3N4 and Twin-G/hBN vdW heterojunctions using first-principles calculations. The results show that Twin-G/g-C3N4 retains a staggered type-II alignment, benefiting efficient photogenerated carrier separation. In contrast, Twin-G/hBN exhibits a type-I alignment. External electrical fields and tensile strain induce transitions in the bandgap and carrier mobility. The study highlights the potential of Twin-G heterostructures for developing optoelectronic devices.