Highly selective two-color mid-wave and long-wave infrared detector hybrid based on Type-II superlattices.

We report a two-color mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 µm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 µm. The measured current reached the system limit of 0.1 pA at 110 K for 30 µm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 µm, an LWIR selectivity of ~17% was achieved in the MWIR wave band between 3 and 4.7 µm, making the detector highly selective.

Low irradiance background limited type-II superlattice MWIR M-barrier imager.

We report a type-II superlattice mid-wave infrared 320×256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ∼99% operability. The 280 K blackbody's photon irradiance was limited by an aperture and a band-pass filter from 3.6 µm to 3.8 µm resulting in a total flux of ∼5×10(12) ph.cm(-2).s(-1). Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ∼5 pA dark current from the 27 µm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ∼5×10(10) ph.cm(-2).s(-1) and temperature sensitivity of 9 mK with F/2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array's uniform responsivity.

Type-II superlattice dual-band LWIR imager with M-barrier and Fabry-Perot resonance.

We report a high performance long-wavelength IR dual-band imager based on type-II superlattices with 100% cutoff wavelengths at 9.5 µm (blue channel) and 13 µm (red channel). Test pixels reveal background-limited behavior with specific detectivities as high as ~5×10¹¹ Jones at 7.9 µm in the blue channel and ~1×10¹¹ Jones at 10.2 µm in the red channel at 77 K. These performances were attributed to low dark currents thanks to the M-barrier and Fabry-Perot enhanced quantum efficiencies despite using thin 2 µm absorbing regions. In the imager, the high signal-to-noise ratio contributed to median noise equivalent temperature differences of ~20 milli-Kelvin for both channels with integration times on the order of 0.5 ms, making it suitable for high speed applications.