Local Ion Irradiation-Induced Resistive Threshold and Memory Switching in Nb₂O₅/NbO_<i>x</i> Films

Resistive switching devices with a Nb₂O₅/NbO_<i>x</i> bilayer stack combine threshold and memory switching. Here we present a new fabrication method to form such devices. Amorphous Nb₂O₅ layers were treated by a krypton irradiation. Two effects are found to turn the oxide partly into a metallic NbO_<i>x</i> layer: preferential sputtering and interface mixing. Both effects take place at different locations in the material stack of the device; preferential sputtering affects the surface, while interface mixing appears at the bottom electrode. To separate both effects, devices were irradiated at different energies (4, 10, and 35 keV). Structural changes caused by ion irradiation are studied in detail. After successful electroforming, the devices exhibit the desired threshold switching. In addition, the choice of the current compliance defines whether a memory effect adds to the device. Findings from electrical characterization disclose a model of the layer modification during irradiation

Continuous Wave Nanowire Lasing

Tin-doped cadmium sulfide nanowires reveal donor–acceptor pair transitions at low-temperature photoluminescence and furthermore exhibit ideal resonator morphology appropriate for lasing at continuous wave pumping. The continuous wave lasing mode is proven by the evolution of the emitted power and spectrum with increasing pump intensity. The high temperature stability up to 120 K at given pumping power is determined by the decreasing optical gain necessary for lasing in an electron–hole plasma

Active Optical Metasurfaces Based on Defect-Engineered Phase-Transition Materials

Active, widely tunable optical materials have enabled rapid advances in photonics and optoelectronics, especially in the emerging field of meta-devices. Here, we demonstrate that spatially selective defect engineering on the nanometer scale can transform phase-transition materials into optical metasurfaces. Using ion irradiation through nanometer-scale masks, we selectively defect-engineered the insulator-metal transition of vanadium dioxide, a prototypical correlated phase-transition material whose optical properties change dramatically depending on its state. Using this robust technique, we demonstrated several optical metasurfaces, including tunable absorbers with artificially induced phase coexistence and tunable polarizers based on thermally triggered dichroism. Spatially selective nanoscale defect engineering represents a new paradigm for active photonic structures and devices

Active Optical Metasurfaces Based on Defect-Engineered Phase-Transition Materials

Active, widely tunable optical materials have enabled rapid advances in photonics and optoelectronics, especially in the emerging field of meta-devices. Here, we demonstrate that spatially selective defect engineering on the nanometer scale can transform phase-transition materials into optical metasurfaces. Using ion irradiation through nanometer-scale masks, we selectively defect-engineered the insulator-metal transition of vanadium dioxide, a prototypical correlated phase-transition material whose optical properties change dramatically depending on its state. Using this robust technique, we demonstrated several optical metasurfaces, including tunable absorbers with artificially induced phase coexistence and tunable polarizers based on thermally triggered dichroism. Spatially selective nanoscale defect engineering represents a new paradigm for active photonic structures and devices