Surface and Physical Properties Modifications of Electron Beam-Irradiated Monolayer MoS2-Au Heterointerface at Nanoscale

Controlled manipulation of physical properties and creating complex surface features-nanosculpting-through particle irradiation is of immense interest in two-dimensional transition metal dichalcogenides (TMDs). In this work, we investigated the influence of SEM-generated low energy electron beam of 15 keV (electron flux 1.9 x 10(7)e(-)s/nm(2)) on exfoliated monolayer MoS2 -gold interface for 15-600 s irradiation exposure. The mechanistic aspects including displacement damage, desorption, and dissociation via core hole Auger decay were proposed ,while morphology is evolved, and lattice defects (sulfur vacancies/nanoholes) are created affecting optical/electronic properties at nanoscale. We employed optical spectroscopy (PL and Raman), and electron and scanning probe microscopy, revealing spatial variations unique to topography, identifying defects, and quantifying surface work function (WF), respectively. Specifically, the monolayer surface structuration showed distinct inside-out concentric ring, starting at 120 s and irreversibly beyond >= 180 s prevailing Knotek-Feibelman mechanism, led by dissociation of ions following ionization (radiolysis), in contrast to primarily knock-on (atomic displacement) damage. We unraveled the importance of defect control of monolayer MoS2 leaving patches in the center (inner region) and edge constructs (outer region) due to metal ion movement, suggested by variation in WF ranging from 4.9 eV +/- 0.006 eV (outer) to 5.2 +/- 0.006 eV (inner) attributed to MoSxOy/MoO3-x chemical species. Tip-enhanced Raman spectroscopy (TERS) was instrumental in elucidating nanoscale inhomogeneities and molytrioxide-related defects besides nanovoids. Determining the impacts of these defects on properties is crucial while simultaneously sculpting desired structures, fabricating devices, doping in MoS2 , and for use in harsh conditions or a space radiation environment.

Automated summary

Controlled manipulation of physical properties and creating complex surface features-nanosculpting-through particle irradiation is studied in this work. The influence of SEM-generated low energy electron beam on MoS2-gold interface is investigated through irradiation exposure. Mechanistic aspects and the evolution of morphology and lattice defects are examined, while optical and electronic properties are affected at nanoscale. The importance of defect control of monolayer MoS2 and the impacts of these defects on properties are revealed. The use of TERS is instrumental in elucidating nanoscale inhomogeneities and molytrioxide-related defects.