Abstract

Metamaterials-based nano-resonators have been extensively studied due to their precise controllability for tuning electromagnetic waves, while it is difficult to map the effects of resonating-light on electrical-transport. Here, conductivities and the effects of charge-traps with nanoscale resolutions are mapped in Ge2Sb2Te5 (GST)-based nano-resonator under resonant excitations. In this strategy, a high electric-field out of surface-plane is applied through a conducting nano-probe, and the probe scans to induce a phase-transition. Results implicate an insulating-to-conducting-phase transition induced by electric-field, due to the formation of filament-like conducting-paths. Utilizing contrasting electrical and optical properties of conducting- and insulating-phases, nano-resonators are fabricated on the surface of GST. Then, plasmonic-conductivities and the effects of charge-trap in nano-resonators are mapped. Nano-resonators with linear-gratings show plasmonic photocurrent upon illumination at selective-wavelengths depending on grating-elements. Contrarily, square-shaped nano-resonators effectively produce plasmonic effects on a broad wavelength range due to the large number of available modes, as evident from plasmonic-wave simulations. Importantly, plasmonic effects prohibit the re-trapping of carriers, resulting in dramatically low trap densities. Moreover, simulation shows that plasmonic effects are pronounced at short-wavelengths, providing high plasmonic-conductivities and low charge-trap densities. The mapping of plasmonic-transport properties can have significant impacts on basic research and applications of phase-change material-based-plasmonic devices.

http://dx.doi.org/10.1002/adfm.202520251