Resonant-Cavity Infrared Detectors with High Quantum Efficiency and Very Thin Absorbers at 4.0 μm

We report resonant-cavity infrared detectors with absorbers that consist of only five quantum wells, but exhibiting 34% external quantum efficiency at room temperature at the resonant wavelength of 4.0 mu m. The FWHM linewidth is 46 nm, and the peak absorption is enhanced by nearly a factor of 30 over that for a single pass through the absorber. Although the Shockley-Read lifetime in the current material is much shorter than the state of the art, the dark current density is at the level of HgCdTe detectors as quantified by "Rule 07". The Johnson-noise limited detectivity (D*) at 21 degrees C is 7 x 10(9) cm Hz 1/2 /W. We expect that future improvements in the device design and material quality will lead to higher quantum efficiency, as well as a significant reduction of the dark current density consistent with the very thin absorber.