Deep-level defects and their optoelectronic impact in 2D WSe₂ heterostructures

Understanding and controlling native point defects (NPDs) in two-dimensional (2D) transition metal dichalcogenides (TMDs) is essential for optimizing their electronic and optoelectronic functionality. The paper presents an analysis of native point defects (NPD) occurring WSe2, deposited on a Si/SiO2 substrate by the exfoliation method. Deep level transient spectroscopy (DLTS) was employed to quantify electrically active defect levels and to identify dominant NPDs in few-layer WSe₂. The DLTS spectra revealed the presence of two characteristic deep-level traps, which -based on their activation energies and capture cross sections -were attributed to selenium vacancies (VSe) and selenium antisites (SeW). Complementary optical characterization techniques, including photoluminescence (PL) and Raman spectroscopy (RS), further confirmed the structural perturbations associated with these NPDs. To establish the impact of the extracted defect states on charge transport, the experimental results were correlated with theoretically simulated current-voltage (I-V) characteristics. The simulations reproduced the experimentally observed non-ideal electrical behavior, highlighting the role of VSe and SeW centers as efficient non-radiative recombination channels and scattering sites. The combined analysis of the electrical, optical, and simulation results offers a coherent view of how native point defects form in exfoliated WSe₂ and clarifies their influence on devicerelevant charge-transport mechanisms. These results contribute to a deeper understanding of defect physics in 2D TMD materials and offer valuable guidelines for improving the performance of WSe₂ -based electronic and optoelectronic devices.