Bias Reconfigurable Photoresponse of an Infrared Nanocrystal Film Integrated into a Coupled Fabry-Perot Resonator

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 nanocrystal films 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, increasing 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.