Electric-field-controlled Schottky barriers in BSe/M2CF2 (M = Ta, W) van der Waals heterostructures: A computational study

Abstract

Constructing two-dimensional (2D) van der Waals (vdW) heterostructures is regarded as an effective strategy to explore novel properties and enhance the performance of 2D materials. Herein, taking full advantage of boron selenide (BSe) and MXenes, 2D BSe/MXene vdW heterostructures are designed and their electronic and interfacial properties are investigated via first-principles calculations, by using BSe/Ta2CF2 and BSe/W2CF2 as models. The band structures of the BSe and M2CF2 (M = Ta, W) layers in the BSe/M2CF2 heterostructures are preserved quite well due to the weak vdW interlayer interaction. The Fermi level shifts towards the conduction band minimum of the BSe layer, leading to an n-type Schottky contact. Interestingly, the interface charge redistribution in BSe/W2CF2 is more pronounced compared to BSe/Ta2CF2, which can be attributed to the disparity in electronegativity between Ta and W. In particular, the Schottky barrier heights of both heterostructures vary linearly with the vertical electric field within a certain range. This allows for the tuning of the Schottky contact from n-type to p-type. However, the variation rate in BSe/W2CF2 is comparatively lower than that in BSe/Ta2CF2. Moreover, when the positive electric field exceeds 1.0 V/Å, a transition from the Schottky contact to the Ohmic contact in BSe/W2CF2 occurs, whereas the contact remains the Schottky contact in BSe/W2CF2. This work offers valuable insights into developing electronic nano-devices with tunable Schottky barriers using vdW heterostructures.