Using non contact atomic force microscopy to measure single electron charging events in WSe2 defects

Defects in transition metal dichalcogenides exhibit novel properties that make them useful as single photon emitters and for advanced doping schemes. However, understanding their properties requires microscopic probes that can directly relate atomic and electronic structure. In this talk, we will present results from cryogenic non-contact atomic force microscopy (nc-AFM) measurements that utilize conductive tips to probe surface and sub-surface defects in CVT-grown WSe₂. Sweeping the tip-sample voltage and measuring the resonant frequency offset of the tip allows us to resolve single electron charging events within certain defects. We show how a careful analysis of these charging processes can reveal both the energetic structure and depth of defects. We relate our findings to optical measurements of identically prepared samples and report on progress in combining nc-AFM measurements with in situ photoluminescence spectroscopy.