Area-Selective Defect-Related Modulation of Optical and Electrical Properties of Monolayer Molybdenum Disulfide by Focused-Laser Irradiation

Featured Application Two-dimensional materials-based devices and sensors. Molybdenum disulfide (MoS2) has been actively explored as a direct bandgap semiconductor in the monolayer (ML) limit for various applications due to its prominent physical properties and stability. In order to broaden its application range further, diverse treatments have been developed to modulate the properties of ML-MoS2. The native point defects, such as S vacancies, are known to activate surface charge transfer doping in ML-MoS2. Unlike conventional semiconductors, ML-MoS2 shows distinct excitonic transitions that can be exploited for controlling its optical, optoelectronic, and electric characteristics via coupling with defect-driven doping. Here, the ambient photoluminescence (PL) of ML-MoS2 could be increased by similar to 1500% at the center of focused-laser irradiation (FLI). Expectedly, the PL intensity varied spatially along with exciton-trion transitions across the irradiation spot due to the Gaussian profile of laser intensity. Then, nano-Auger electron spectroscopy (n-AES) revealed that the spectral fraction of exciton PL increased by similar to 69.2% while that of trion PL decreased by similar to 49.9% with increasing S deficiency up to similar to 13.4 +/- 3.5%. Cryogenic PL and field-effect transistor experiments were also performed to understand the defect-related phenomena comprehensively. This novel experimental combination of FLI with an n-AES probe provides a facile, effective, and cost-efficient approach for exploring defect effects in two-dimensional structures.

Automated summary

Researchers have discovered that the optical, optoelectronic, and electric characteristics of monolayer molybdenum disulfide can be controlled through defect-induced doping. By using focused laser irradiation, the photoluminescence intensity of monolayer molybdenum disulfide was increased by approximately 1500%. Nano-Auger electron spectroscopy revealed changes in the photoluminescence peaks. This study provides a facile, effective, and cost-efficient approach for exploring defect effects in two-dimensional structures.