High speed, antenna-enhanced 10.3 μm quantum cascade detector.

The strong potential of intersubband detectors in the field of mid-infrared photodetection places this technology as a relevant alternative to HgCdTe detectors in the race for ultrafast operation. While their extremely short photocarrier's lifetime opens up possibilities of detection beyond 100 GHz, it is also the main reason for their comparatively high dark current. Here, a photovoltaic quantum cascade detector at 10.3 μm, embedded in a metal–metal patch antenna is presented in both direct and heterodyne detection schemes. In DC, a responsivity of 122 mA/W at 77 K and 85 mA/W at 295 K is reached. More strikingly, the device shows temperature independent heterodyne response with a capacitance-limited cutoff frequency of 25 GHz both at 77 K and room temperature. It is modeled quantitatively by means of an equivalent RC-circuit picture stemming from microscopic transport considerations. [ABSTRACT FROM AUTHOR]