Demonstration of type-II superlattice MWIR minority carrier unipolar imager for high operation temperature application

Abstract

An InAs/GaSb type-II superlattice-based mid-wavelength infrared (MWIR) 320×256 unipolar focal plane array (FPA) using pMp architecture exhibited excellent infrared image from 81 to 150 K and ∼98% operability, which illustrated the possibility for high operation temperature application. At 150 K and -50 mV operation bias, the 27 μm pixels exhibited dark current density to be 1.2×10(-5) A/cm(2), with 50% cutoff wavelength of 4.9 μm, quantum efficiency of 67% at peak responsivity (4.6 μm), and specific detectivity of 1.2×10(12) Jones. At 90 K and below, the 27 μm pixels exhibited system limited dark current density, which is below 1×10(-9) A/cm(2), and specific detectivity of 1.5×10(14) Jones. From 81 to 100 K, the FPA showed ∼11 mK NEDT by using F/2.3 optics and a 9.69 ms integration time.

Design of InAs/GaSb superlattice infrared barrier detectors

“…In the literature, two different SL material systems are generally reported as material for the barrier composing nBp and pBp structures, either the InAs/GaSb/AlSb/GaSb SL [9,29,30] or the InAs/AlSb SL [11]. We have chosen to study the InAs/GaSb/AlSb/GaSb SL as it offers more flexibility in the choice of the band offset thanks to the additional GaSb layer.…”

Design and Development of Two-Dimensional Strained Layer Superlattice (SLS) Detector Arrays for IR Applications

“…These differ primarily in their usage of the M-structure barrier, which is employed to block hole majority carriers in the pMp architecture [94], while in p-π-M-n devices to suppress tunneling current [95].…”

“…Figure 14 shows the band structure and working principle of a pMp detector, along with key associated performance characteristics [22,95]. Devices comprising the pMp architecture consist of two p-doped superlattice active regions and a thin valence band M-barrier having zero conduction band discontinuity with respect to the p-type active regions [79].…”

“…In comparison with a basic p-π-n type design, the electric field in the depletion region of a p-π-M-n detector is reduced, and the tunneling barrier between the p and the n regions spatially broadened [95]. The first reported p-π-M-n detector which comprised a 500 nm M-barrier exhibited R 0 A of 200 Ω cm 2 at 77 K, approximately one order of magnitude higher than that of a comparable p-π-n device without an M-layer barrier [94].…”

Ga-free InAs/InAsSb type-II superlattice (T2SL) photodetector for high operating temperature in the midwave infrared spectral domain

“…In that way, one can consider a type-II InAs/GaSb superlattice (T2SL) on GaSb substrate 4 . Unfortunately, such T2SL devices are penalized by a low minority carrier lifetime (around 100 ns in the MWIR) due to the presence of Ga-related native defects in the SL period 5 leading typically to a temperature operation lower than 110K for a 5μm cut-off 6 . An extended cut-off was achieved recently by using an InAsSb bulk absorber material with a antimony content higher than the one lattice-matched to GaSb, leading to a cut-off wavelength higher than 5µm.…”