Thickness-dependent bandgap and electrical properties of GeP nanosheets

Abstract

Two-dimensional GeP nanosheets were synthesized to probe the thickness-dependent band gap and electrical properties, which were supported by first-principles calculations that predicted the band gap of monolayers to be 2.3 eV.

Tunable Electronic Properties and Potential Applications of 2D GeP/Graphene van der Waals Heterostructure

“…The primitive cell of the monolayered GeP is rectangular, and the relaxed lattice constant of the primitive cell is a = 3.621 Å and b = 21.246 Å, which is in good agreement with previous calculations implemented by VASP code 15,20,22. In order to model the GeP/Gr heterostructure, the graphene supurcell of 3 × 5 × 1 rectangular unitcell consisting of 60 carbon atoms is used.…”

“…The 2D GeP has work function W GeP = 4.84 eV. It is noticed that the band edges of the monolayered GeP, as presented in Figure 2c, are within the values of −3.75 eV (−6.06 eV) for the CBM (VBM) obtained by HSE calculation 22. Therefore, our computations are considered to provide quantitatively reasonable results for the influences of graphene contact to the 2D GeP.…”

“…The indirect bandgap of the GeP supercell is 1.808 eV, which is larger than the value obtained by augmented plane‐wave (APW) method (1.610 eV) and smaller than that obtained from HSE bybrid functional calculation (2.309 eV) 46. We stress that the GGA‐PBE reported a smaller bandgap than the experimental observation,22 nevertheless the calculated bandgap is always in consistence with the transport bandgap. This is due to the error cancellation that both many‐body effects and long‐term Coulomb interactions are neglected in GGA‐PBE calculations 47.…”

“…The graphene contact on the 2D GeP is determined to be physical adsorption 44. Recent experimental characterization has shown the distance of 2.1 Å along c ‐axis for the bulk GeP,22 therefore the monolayered GeP and graphene are connected by vdW interaction. Hence, the equilibrium distance of GeP/Gr is smaller than the corresponding value of the blue phosphorus/Gr heterostructure 45.…”

“…The 2D GeP is anticipated to have excellent optical absorption of visible light and the measured absorption peak at about 532 nm. Very recently, Kim et al have shown that large on/off current ratio can be obtained for the 2D GeP, suggesting it can be potentially used for nanoelectronics 22. Furthermore, the 2D ultrathin GeP deposited on Si nanowire is shown to significantly improve the current density for application of solar‐driven water‐splitting.…”