Quantum plasmonic doping in bilayer 2D heterostructures

Two-dimensional (2D) semiconductors exhibit interesting opto-electronic properties due to their direct bandgap and strong light-matter interactions. Various approaches have been developed to enhance and tune photoluminescence (PL) of 2D transition metal dichalcogenides (TMDs) such as electrical and chemical doping. Here we demonstrate quantum plasmonic doping originating from hot electron tunneling between a gold-coated plasmonic tip and bilayer MoS₂-WS₂ heterostructure. We used optimized near-field spectroscopy in the quantum plasmonic regime to obtain both tip-enhanced Raman scattering (TERS) and tip-enhanced photoluminescence (TEPL) images of bilayer MoS₂-WS₂ heterostructures on Si/SiO₂ substrate without the plasmonic gap mode. Simultaneously, contact potential difference (CPD) and capacitance mapping confirms the accumulation of charges. Quantum plasmonic doping is a new technique for tuning opto-electronic properties of 2D heterostructures with promising future applications.