Spatial-Selective Electrostatic Doping of Two-Dimensional Semimetals via Substrate Heterointerface Engineering

Precise, area-selective control of electrostatic doping in two-dimensional (2D) semimetallic materials (SMs) is crucial for their application in emerging heterostructures and device technologies. Traditional doping methods often struggle to achieve high carrier densities without compromising stability. In this study, we present a novel approach for spatially selective electrostatic doping of 2D semimetals using a diamond-like carbon (DLC) thin film substrate with implanted heteroatoms. First-principles calculations were conducted to investigate the electrostatic interactions between monolayer 2D SMs and spatially implanted ions within the DLC substrate. Computational results indicate that maximum doping is achieved when implanted heteroatoms diffuse from the DLC to the heterointerface in single atomic form, which results in the strongest charge transfer to the overlayered 2D SM. This mechanistic insight is corroborated by experimental studies focusing on graphene monolayers electrostatically doped by gallium heteroatoms in DLC substrate. In this setup, annealing-driven diffusion of FIB-implanted gallium ions at the graphene-DLC heterointerface enables precise tuning of the work function and carrier concentration of the graphene monolayer, with maximum carrier densities reaching 7×10¹³ cm^-2. Extension of this doping scheme to other elements implantable in DLC substrate and to various monolayer 2D semimetals at the heterointerface demonstrates the possibility to achieve both n- and p-type doping in monolayer 2D SMs. These results highlight the efficiency and versatility of our method for tuning the electronic behavior of a wider range of 2D semimetals, paving the way for fabricating advanced electronics based on SMs such as graphene and WTe₂. The ability to achieve stable, spatial-selective doping without perturbing the lattice structure also provides promising avenues for investigating novel many-body physics and carrier-dependent topological properties of various 2D semimetals.