Bias reconfigurable photoresponse of infrared nanocrystal film integrated into a coupled Fabry-Perot resonator
Résumé
The coupling of a photonic structure to a nanocrystal film enables light focusing over a distance compatible with the charge diffusion length. This strategy has been implemented in infrared sensors based on a nanocrystal film to maximize their absorption. Here, we demonstrate that the photonic structure can be further exploited to generate a bias-reconfigurable photoresponse. To reach this goal, we use a coupled Fabry-Perot structure that can be seen as a periodic grating with two different cavities per period. The two cavities are coupled and a resonance appears that increases the effective absorption coefficient by a factor of 30 compared to standard interdigitated electrodes. When connected in the appropriate configuration, this device enables the turning-on and-off of part of the spectral response (over a factor of 25 in magnitude) simply by tuning the applied bias (<1 V). Finally, we also demonstrate that this resonator geometry is promising for integration at the focal plane array level since the resonance is maintained for a pixel size as small as 10 µm.
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