Gallium doping-assisted giant photoluminescence enhancement of monolayer MoS2 grown by chemical vapor deposition

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted enormous research interest owing to their unique photo-physics and excellent optoelectronic properties. However, the ubiquitous defects in 2D TMDCs greatly affect the optoelectronic properties of them. For example, the prototype molybdenum disulfide (MoS2) exhibits very poor photoluminescence (PL) due to the high defect density. Here, we report a defect repair strategy based on a facile one-step chemical vapor deposition method that achieves two orders of magnitude enhancement in photoluminescence (PL) and one order of magnitude prolonging in carrier lifetime. Interestingly, we can controllably synthesize Ga-doped samples with different morphologies by adjusting the ratio of precursors, and the PL intensities at the central and edge regions are quite different. Combined with scanning transmission electron microscopy characterization, we systematically elucidate this growth behavior and obtain a more precise defect repair strategy. This strategy of selectively repairing the defects of monolayer MoS2 by gallium doping to achieve significant enhancement of photoluminescence may provide a facile and feasible method for the regulation of optoelectronic properties of 2D materials.