Role of defect-induced thermal resistance in the photoluminescence intensity of CVD-grown monolayer : Short-term aging effects
Phys. Rev. B 114, 055418 – Published 24 July, 2026
DOI: https://doi.org/10.1103/hrx3-qccn
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) grown by chemical vapor deposition (CVD) have emerged as promising optoelectronic materials owing to their high optical quality and scalability. However, the stability and degradation of as-grown 2D TMDCs remain critical for realizing their potential applications. We systematically investigate the short-term aging effects of CVD-grown monolayer flakes on their electronic, optical, and thermal properties. We found that the total photoluminescence (PL) intensity of monolayer was drastically reduced ( times) within 24 hours after growth. Kelvin probe force microscopy was employed to evaluate the short-term aging effects through surface potential mapping. Surface oxidation mediated by sulfur vacancies, predominantly driven by over , was identified as the main cause of optical deterioration. An increase in the work function with time was attributed to -type doping induced by oxidation. Contrary to earlier reports, the total PL intensity of monolayer decreased even with -type doping, which is explained by defect-induced thermal resistance. The increased thermal resistance substantially raises the local temperature, thereby reducing the PL quantum yield. The variation of thermal resistance with time was confirmed using power-dependent Raman spectroscopy. In addition, a surface potential difference of mV was observed between the edge and basal plane, and was attributed to spatial variation in sulfur vacancy density. We also found that molecular adsorption differs at the edge (chemisorption) and the basal plane (physisorption) of monolayer . These findings provide new insights into the degradation mechanisms of 2D semiconductors and highlight the critical role of defect-induced thermal resistance in photoluminescence.
