Toward nanocrystal-based active nanophotonic device
Résumé
One of the great interests for colloidal nanocrystals (NCs) is their optical tunability controlled by the synthesis processes. Nonetheless, for NC-based devices, post-fabrication tunability remains very limited.1 Here, we show a NC-based active photonic device where the optical tunability is achieved thanks to an inhomogeneous absorption obtained by coupling a HgTe nanocrystal2 array to a plasmonic cavity. Bias tunability results from hopping transport which enables tuning the charge collection from low-field regions (in the very vicinity of the electrodes) to high-field ones (away from the electrodes).3 As a result, we observe a 15 meV blueshift of the photocurrent spectrum for a device working in the extended short-wave infrared under the application of 3 V bias voltage.3 This shift has the opposite sign with respect to the redshift expected from Stark effect while occurring under much weaker applied electric fields. We show that hopping transport, often seen as a bottleneck to achieve high-performing optoelectronic devices, can play an essential role in the operation of active photonic devices.