Romain Chevallier

InAs/InAs1−xSbx type-II superlattices for high performance long wavelength infrared detection

High performance long-wavelength infrared nBn photodetectors based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate have been demonstrated. The photodetectors 50% cut-off wavelength was ∼10 μm at 77 K. The photodetector with a 6 μm-thick absorption region exhibited a peak responsivity of 4.47 A/W at 7.9 μm, corresponding to a quantum efficiency of 54% at −90 mV bias voltage under front-side illumination and without any anti-reflection coating. With an R × A of 119 Ω·cm2 and a dark current density of 4.4 × 10−4 A/cm2 under −90 mV applied bias at 77 K, the photodetector exhibited a specific detectivity of 2.8 × 1011 cm. Hz/W.

High performance photodiodes based on InAs/InAsSb type-II superlattices for very long wavelength infrared detection

Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices are demonstrated on GaSb substrate. A heterostructure photodiode was grown with 50% cut-off wavelength of 14.6 μm. At 77 K, the photodiode exhibited a peak responsivity of 4.8 A/W, corresponding to a quantum efficiency of 46% at −300 mV bias voltage from front side illumination without antireflective coating. With the dark current density of 0.7 A/cm2, it provided a specific detectivity of 1.4 × 1010 Jones. The device performance was investigated as a function of operating temperature, revealing a very stable optical response and a background limited performance below 50 K.

High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs1-xSbx/AlAs1-xSbx superlattices

A high-performance short-wavelength infrared n-i-p photodiode based on InAs/InAs1−xSbx/AlAs1−xSbx type-II superlattices on GaSb substrate has been demonstrated. The device is designed to have a 50% cut-off wavelength of ∼1.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.47 A/W at 1.6 μm, corresponding to a quantum efficiency of 37% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 285 Ω cm2 and a dark current density of 9.6 × 10−5 A/cm2 under −50 mV applied bias at 300 K, the photodiode exhibited a specific detectivity of 6.45 × 1010 cm Hz1/2/W. At 200 K, the photodiode exhibited a dark current density of 1.3 × 10−8 A/cm2 and a quantum efficiency of 36%, resulting in a detectivity of 5.66 × 1012 cm Hz1/2/W.

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

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.

Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier

Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAs0.10Sb0.90/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm2 and a dark current density of 8 × 10−3 A/cm2 under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 1010 cm·Hz1/2/W. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10−9 A/cm2 and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 1013 cm·Hz1/2/W.

Background–limited long wavelength infrared InAs/InAs1− xSbx type-II superlattice-based photodetectors operating at 110 K

We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAs1− xSbx type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ∼10 μ m at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R × A of 664 Ω · cm 2 and a dark current density of 8 × 10−5 A/cm2, under −80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 × 1011 cm· Hz / W and a background–limited operating temperature of 110 K.

Bias-selectable nBn dual-band long-/very long-wavelength infrared photodetectors based on InAs/InAs1-xSbx/AlAs1-xSbx type-II superlattices /639/301/1005/1009 /639/766/1130/2799 /128 /145 /144 /142/126 /120 article

Type–II superlattices (T2SLs) are a class of artificial semiconductors that have demonstrated themselves as a viable candidate to compete with the state–of–the–art mercury–cadmium–telluride material system in the field of infrared detection and imaging. Within type–II superlattices, InAs/InAs1−xSbx T2SLs have been shown to have a significantly longer minority carrier lifetime. However, demonstration of high–performance dual–band photodetectors based on InAs/InAs1−xSbx T2SLs in the long and very long wavelength infrared (LWIR & VLWIR) regimes remains challenging. We report the demonstration of high–performance bias–selectable dual–band long–wavelength infrared photodetectors based on new InAs/InAs1−xSbx/AlAs1−xSbx type–II superlattice design. Our design uses two different bandgap absorption regions separated by an electron barrier that blocks the transport of majority carriers to reduce the dark current density of the device. As the applied bias is varied, the device exhibits well–defined cut–off wavelengths of either ∼8.7 or ∼12.5 μm at 77 K. This bias–selectable dual–band photodetector is compact, with no moving parts, and will open new opportunities for multi–spectral LWIR and VLWIR imaging and detection.

Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors

Microjunction InAs/InAs1−xSbx type-II superlattice-based long-wavelength infrared photodetectors with reduced dark current density were demonstrated. A double electron barrier design was employed to reduce both bulk and surface dark currents. The photodetectors exhibited low surface leakage after passivation with SiO2, allowing the use of very small size features without degradation of the dark current. Fabricating microjunction photodetectors (25 × 25 µm2 diodes with 10 × 10 µm2 microjunctions) in combination with the double electron barrier design results in a dark current density of 6.3 × 10−6 A/cm2 at 77 K. The device has an 8 µm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 µm-thick absorption region, which results in a specific detectivity value of 1.2 × 1012 cm·Hz1/2/W.

InAs/InAs1-xSbx type-II superlattices for high performance long wavelength infrared detection

We report InAs/InAs1-xSbx type-II superlattice base photodetector as high performance long-wavelength infrared nBn device grown on GaSb substrate. The device has 6 μm-thick absorption region, and shows optical performance with a peak responsivity of 4.47 A/W at 7.9 μm, which is corresponding to the quantum efficiency of 54% at a bias voltage of negative 90 mV, where no anti-reflection coating was used for front-side illumination. At 77K, the photodetector’s 50% cut-off wavelength was ~10 μm. The device shows the detectivity of 2.8x1011 cm.√Hz/W at 77 K, where RxA and dark current density were 119 Ω•cm2 and 4.4x10-4 A/cm2 , respectively, under -90 mV applied bias voltage.

Low-frequency noise in mid-wavelength infrared InAs/GaSb type-II superlattice based focal plane arrays

Low-frequency noise has been studied in a mid-wavelength infrared InAs/GaSb type-II superlattice-based focal plane array. Low-frequency noise is observed under reverse bias but not at zero bias, even in the presence of photo-current. The magnitude of low-frequency noise was separately measured as a function of operating temperature and operation bias. The low-frequency noise is linearly correlated with the generation-recombination component of the dark current. No correlation of low-frequency noise with photo-current or diffusion dark current was found.