Investigation On Surface Modification Of Two-Dimensional Molybdenum Disulfide

Two-dimensional?2D?transition metal dichalcogenides?TMDCs?like Molybdenum disulfide?MoS₂?,Tungsten disulfide?WS₂?possesses a decent bandgap and mechanical flexibility,therefore,are regarded as potentials,next-generation candidates for nano-electronic devices.They are receiving considerable attention for use in the optical and electronic devices,due to their impressive electrical,mechanical,optical,and chemical properties.In this work,we employed plasma treatment and gallium ion irradiation with the aid of a focused ion beam?FIB?system to tune the properties of TMDCs.Firstly,the structural,mechanical,and surface potential?SP?characteristics of single-layer MoS₂ films subjected to oxygen plasma treatment were investigated.Comparison of the Raman spectra?RS?of single-layer MoS₂ films before and after plasma treatment revealed that plasma treatment caused mechanical stripping.The difference between E¹_2g and A_1g peaks and the position of the longitudinal acoustic mode changed considerably ensuing oxygen plasma treatment.Atomic force microscopy?AFM?was used to explore the changes of the structure,mechanical behavior,and SP of the MoS₂ films induced by plasma treatment.Root mean square?RMS?values were used to analyze the changes of surface roughness,adhesion,and the SP of the MoS₂ films induced by oxygen plasma treatment.The RMS roughness of the films first increased and then decreased with increasing plasma treatment duration.The defect content of the MoS₂ films was increased by oxygen plasma treatment,and the SP decreased considerably.Secondly,the friction force and surface modification of MoS₂,have been employed to study irradiated MoS₂ based on different times by controlling the energy and intensity of the Ga ion beam via FIB.The RS discovered that the induced tensile strain by the irradiation initially increased the work function and the crystal lattice changed by doping the flakes.Similarly,AFM topographical studies of MoS₂ under various dwell times before and after irradiation demonstrate a direct relationship with the irradiation time and friction force.Therefore,an irradiation time increases as the friction value decreases as mentioned above.Hence,increasing the resident time causes change within the irradiated MoS₂ flakes,resulting in a gradual reduction in the friction value.