L2D2 at MRS Spring 2023: Gate-Modulated Photoluminescence for WSe₂ Defect Metrology and Healing

The L2D2 consortium was represented at the Materials Research Society Spring Meeting 2023, held 10–14 April 2023 in San Francisco.

On 12 April, Prof. Doron Naveh (Bar-Ilan University) delivered an oral presentation titled “Defect Healing and Defect Metrology of WSe₂ by Gate-Modulated Photoluminescence.” The talk addressed a central challenge for 2D semiconductors: how to quantify and mitigate point defects that can dominate optical response and device behavior.

Building on photoluminescence as a core diagnostic, the work introduced gate-modulated spectroscopy to deliberately enhance charge trapping and detrapping at defect sites, enabling a lower-bound estimate of intrinsic defect density in both CVD-grown and exfoliated WSe₂. The presentation also highlighted device design strategies—showing how a thin hBN buffer can suppress hysteresis linked to injected holes—alongside a chemical healing route that replaces oxygen-related defects with sulfur through thiol adsorption, followed by rapid thermal treatment to trim carbon chains. The effectiveness of defect elimination was verified through multiple complementary measurements, including XPS, cryogenic photoluminescence, and gate-modulated photoluminescence, and the detrapping behavior was discussed in terms of an activated process with an associated energy barrier that provides insight into defect-state binding energies.

Participation in MRS Spring 2023 supported L2D2’s continued engagement with the international materials community and provided a strong venue to share advances that connect defect metrology with practical healing strategies for layered semiconductor technologies.