研究目的
Exploring the concept of dielectric band gap engineering, i.e., the controlled manipulation of the band gap of a semiconductor via its dielectric environment, in two-dimensional semiconductors.
研究成果
Our ab initio GW calculations show that it is possible to control the quasiparticle band gap of an atomically thin 2D semiconductor by varying the doping concentration in a nearby graphene sheet. The physical mechanism underlying the band gap renormalization is that the size of the screening cloud dressing an electron/hole of the 2D semiconductor, which determines its self-energy, is controlled by the screening ability of the graphene. Our work highlights the unique opportunities for shaping electron energy landscapes in 2D materials by dielectric engineering without altering the atomic or electronic integrity of the 2D material itself.
研究不足
The theoretical treatment is limited by the assumption of static screening, which may not be valid when the dielectric function shows weak variation with frequency up to a characteristic frequency given by the exciton binding energy.
1：Experimental Design and Method Selection:
The study uses first-principles calculations based on the GW self-energy approximation to explore the concept of dielectric band gap engineering in 2D semiconductors.
2：Sample Selection and Data Sources:
The study considers a van der Waals heterostructure consisting of a 2D semiconductor placed on a graphene sheet, with various types of 2D semiconductors explored.
3：List of Experimental Equipment and Materials:
The calculations are made possible by the recently developed G(cid:2)W method, which calculates the change in the GW self-energy due to the additional screening provided by the heterostructure environment, obtained using the quantum electrostatic heterostructure (QEH) model.
4：Experimental Procedures and Operational Workflow:
The QP energies are obtained from the linearized QP equation, and the GW calculations were performed starting from the PBE wave functions.
5：Data Analysis Methods:
The effect of dielectric screening on the QP band gap is analyzed, and the band gap renormalization is explained within a quasiparticle picture.
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