Graded-barrier heterostructures for photovoltaic split-off infrared detection

We report photovoltaic infrared detectors based on graded-barrier asymmetric heterostructures. Detectors with a single period structure showed room temperature operation with a zero-response threshold of ~4 μm, and a comparable detectivity to 30-period photoconductive split-off detectors reported previously. An additional long-wavelength response peak of up to 8 μm was also observed when the operating temperature was lowered to 80 K. The detectivities at 80 K for wavelenghs of 2.5 μm and 5 μm were 2×10¹³ and 3×10¹² cm Hz^1/2/W, respectively.