Material Realistic Description of Coulomb Engineered Two-dimensional Materials

Heterojunctions are building blocks of various applications in modern optoelectronics. Common heterojunctions rely on interfaces of different materials in order to gain the desired spatial band-gap modulations.
We investigate a new type of lateral heterojunction imprinted externally into an otherwise homogeneous monolayer of a 2d material. In 2d semiconductors the Coulomb interaction can modify band gaps on an eV scale and can be drastically manipulated by external screening. This allows to tune the local band gaps within a monolayer by laterally structured dielectric surroundings and leads to characteristics of a heterojunction in the local density of states with a spatially sharp band gap modulation.
By means of ab-initio calculations we study the nature and tunability of this band-gap modulation in 2d semiconductors in dependence of the chosen environment. Therefore we place a homogeneous monolayer on different laterally structured substrates. We identify optimal candidates for Coulomb engineered 2d systems and study their electronic transport properties depending on external electrical fields and charge doping.