Resonant structures for infrared detection.

We are developing resonator-quantum well infrared photodetectors (R-QWIPs) for long-wavelength applications. Detector pixels with 25 μm pitch were hybridized to fan-out circuits for radiometric measurements. With a moderate doping of 0.5×1018  cm-3, we achieved a quantum efficiency (QE) of 37% and conversion efficiency (CE) of 15% in a 1.3 μm thick active material and 35% QE and 21% CE in a 0.6 μm thick active material. Both detectors are cutoff at 10.5 μm with a 2 μm bandwidth. The temperature at which photocurrent equals dark current is about 65 K under F/2 optics. The thicker detector shows a large QE polarity asymmetry due to nonlinear potential drop in the QWIP material layers.