2026/07/28 by Dedi Sutarma, Peter Kratzer
Physics and Astronomy · #cond-mat.mtrl-sci
Aiming at two-dimensional materials for high-efficiency optoelectronics, WS2/ZnO heterostructures are computationally screened for their facet-dependent electronic properties and interfacial defect thermodynamics using first-principles hybrid functional calculations. Interface comparison identifies the non-polar (1010) m-plane as the optimal substrate facet, maintaining a direct 2.42~eV bandgap and a robust type-I band alignment. Isolated sulfur (VS) and interfacial oxygen (VO) vacancies introduce deep non-radiative recombination centers. Conversely, zinc vacancies (\mathrmVZn) act as shallow acceptors near the valence band edge, contributing to unintentional p-type behavior. Analysis of defect pairs reveals that neutral vacancies cluster across the van der Waals gap due to favorable binding energies. Under n-type conditions, defects stabilize as charged species. Although inter-layer Coulomb repulsion weakens the binding energy of (VS - \mathrmVZn)'''' pairs, their formation energy drops to 2.61~eV under anion-poor conditions, making the -4 cluster the most thermodynamically abundant defect pair at the interface. Furthermore, native \mathrmVZn prevents the Fermi level rise typically induced by interstitial hydrogen (Hi), distributing donated electrons into shallow acceptor states and preserving host band edge rigidity. These findings establish a microscopic framework for substrate selection and defect engineering in 2D/3D hybrid light-emitting diodes.