We demonstrate localization and field-effect spatial control of the plasmon resonance in semiconductor nanostructures, using scattering-type scanning near-field optical microscopy in the mid-infrared region. We adopt InAs nanowires embedding a graded doping profile to modulate the free carrier density along the axial direction. Our near-field measurements have a spatial resolution of 20 nm and demonstrate the presence of a local resonant feature whose position can be controlled by a back-gate bias voltage. In the present implementation, field-effect induces a modulation of the free carrier density profile yielding a spatial shift of the plasmon resonance of the order of 100 nm. We discuss the relevance of our electrically tunable nanoplasmonic architectures in view of innovative optoelectronic devices concepts.
Gate-Tunable Spatial Modulation of Localized Plasmon Resonances / Arcangeli, Andrea; Rossella, Francesco; Tomadin, Andrea; Xu, Jihua; Ercolani, Daniele; Sorba, Lucia; Beltram, Fabio; Tredicucci, Alessandro; Polini, Marco; Roddaro, Stefano. - In: NANO LETTERS. - ISSN 1530-6984. - 16:9(2016), pp. 5688-93-5693. [10.1021/acs.nanolett.6b02351]