No abstract

We report on ultrafast GaN/AlGaN waveguide quantum cascade detectors with a peak detection wavelength of 1.5 μm. Mesa devices with a size of 7 × 7 and 10 × 10 μm2 have been fabricated with radio-frequency impedance-matched access lines. A strong enhancement of the responsivity is reported by illuminating the waveguide facet, with respect to illumination of the top surface. The room temperature responsivity is estimated to be higher than 9.5 ± 2 and 7.8 ± 2 mA/W, while the −3dB frequency response is extracted to be 42 and 37.4 GHz for 7 × 7 and 10 × 10 μm2 devices, respectively.

We report on a GaN/AlN quantum cascade detector operating in an extended spectral range going from the mid-infrared to visible wavelengths. This broadband detection is achieved thanks to the design of active quantum wells supporting five bound-to-bound intersubband transitions. The photodetector exhibits a broad signal between 4.1 μm and 550 nm. The photocurrent persists up to room temperature. The calibrated responsivity at 77 K under irradiation through a 45° angle polished facet amounts to 7 μA/W at a wavelength of 633 nm and is peaked at 14 μA/W at a wavelength of 720 nm.