Ab initio modelling of photodetectors based on van der Waals heterostructures

Two-dimensional (2-D) materials, especially transition metal dichalcogenides (TMDCs), have attracted great attention due to their unique properties and the vast possibility they offer when combined into van der Waals heterostructures (vdWHs), for example in optoelectronic applications. Although various photodetectors based on TMDC vdWHs have been successfully synthesized, an \textit{ab initio} simulation framework dedicated to such devices is still missing. In this work, we investigate two photodetector designs based on MoSe\textsubscript{2}-WSe\textsubscript{2} vdWHs through a recently developed approach combining density functional theory and quantum transport calculations. Geometries with a partial and total TMDC overlap are considered, with a p-doped (n-doped) left (right) extension and an intrinsic region in the middle. We show that the partial overlap structure supports a non-zero photocurrent, even without a built-in potential, contrary to the full overlap structure.