Tuning electronic properties and Schottky contact in graphene-based van der Waals heterostructures by electric gating and interlayer coupling

Poonam Sharma; Archana Sharma; Alok Shukla

doi:10.1103/1qnh-zvzq

paper

Tuning electronic properties and Schottky contact in graphene-based van der Waals heterostructures by electric gating and interlayer coupling

arXiv:2608.16413 · doi:10.1103/1qnh-zvzq

Abstract

Van der Waals heterostructures (vdW HTSs) incorporating graphene (GE) have been an active area of research, both theoretical and experimental, due to their potential to yield devices with a wide variety of applications. In this paper, first-principles calculations are employed to investigate C $_{6}$ N $_{6}$ /GE, hg-C $_{3}$ N $_{4}$ /GE, and C $_{6}$ N $_{6}$ /hg-C $_{3}$ N $_{4}$ 2D vdW HTSs. A systematic analysis of structural and thermodynamic stability, electronic, mechanical, and optical properties of semiconductor/metal and semiconductor/semiconductor interfaces is performed. Both semiconductor/metal HTSs form $n$ -type Schottky contacts, which can be converted into $p$ -type Schottky or Ohmic contacts by tuning the external perpendicular electric field and the interlayer coupling. In the semiconductor/semiconductor C $_{6}$ N $_{6}$ /hg-C $_{3}$ N $_{4}$ HTS, the valence and conduction band edges originate from distinct layers, resulting in a type-II band alignment that promotes efficient electron-hole (e-h) separation. Furthermore, the band alignment can be effectively tuned between type-I and type-II by applying an external electric field and varying the interlayer distance. From the optical absorption spectra of the HTSs, we concluded that the C $_{6}$ N $_{6}$ /GE and hg-C $_{3}$ N $_{4}$ /GE exhibit an optical response across a wide frequency range, whereas the C $_{6}$ N $_{6}$ /hg-C $_{3}$ N $_{4}$ HTS shows prominent activity primarily in the ultraviolet region. Using the $G_{0} W_{0}$ +BSE approach, the exciton binding energies are also calculated for the gapped systems, namely C $_{6}$ N $_{6}$ , hg-C $_{3}$ N $_{4}$ monolayers, and their HTS (C $_{6}$ N $_{6}$ /hg-C $_{3}$ N $_{4}$ ), yielding values of 1.01 eV, 1.14 eV, and 1.18 eV, respectively, highlighting strong e-h interactions. Moreover, the band-edge analysis of C $_{6}$ N $_{6}$ /hg-C $_{3}$ N $_{4}$ HTS further favors pronounced interlayer e-h coupling.

Main Manuscript: 13 figures, 16 pages. Supplemental Material: 9 figures, 6 pages

Tuning electronic properties and Schottky contact in graphene-based van der Waals heterostructures by electric gating and interlayer coupling

Abstract

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