Accurate and efficient prediction of Schottky barrier heights in 2D semimetal/silicon heterojunctions

The accurate prediction of the Schottky barrier height (SBH) holds significant importance for optimizing the performance of semimetal/semiconductor heterojunction devices. Two-dimensional semimetal/semiconductor heterostructures have now been extensively studied experimentally. However, first-principles predictions of the corresponding SBH typically require solving the ab initio Hamiltonian in supercells containing more than 10³ atoms. This high computational complexity not only results in extremely low efficiency but also hinders the design and optimization of heterojunction devices. Herein, we apply density functional theory with a core-level energy alignment method for transition-metal-ditelluride semimetal/silicon junctions, which enables a reduction in supercell size by one order of magnitude. The predicted SBHs show excellent agreement with experiment. We further investigate different 2D semimetal compounds, finding that all candidates exhibit lower SBHs for holes than electrons, with thickness effects becoming negligible beyond three to five layers. This study presents an efficient framework for calculating SBH in complex heterostructures and provides theoretical guidance for the efficient design of high-performance 2D semimetal heterojunction devices.