InAs/GaSb type-II superlattice mid-wavelength infrared focal plane array detectors grown by molecular beam epitaxy

Abstract

We report our recent works on the growth and fabrication of InAs/GaSb type II superlattice detectors by solid source molecular beam epitaxy. Lattice mismatch between the superlattice and the GaSb substrate reached 1.5×10−4. The full width at half maximum of the first order satellite peak from X-ray diffraction was 28″. Full simulation of the X-ray scanning curves showed the detailed composition of the InAsSb interface layers. Single element detectors and focal plane arrays were fabricated using wet chemical etching. The devices with 10ML InAs/10ML GaSb in each superlattice period showed a 50% cutoff wavelength of 5.4μm at 77K. The dark current density at −20mV bias was 3.8×10−7A/cm2 and the resistance–area product at zero bias 7.5×104Ωcm2.The quantum efficiency was measured to be 25%. The blackbody detectivity and the peak wavelength detectivity were 7.6×1011cmHz1/2/W and 3×1012cmHz1/2/W, respectively. The focal plane array was characterized with an integration time of 2.7ms and F/2.0 optics. The percentage of the dead pixels was only 1.8%, non-uniformity 5.41% and a noise equivalent differential temperature 33.4mK.