Center for Quantum Devices - Most Downloaded Journal Articles

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16.	Type-II Antimonide-based Superlattices for the Third Generation Infrared Focal Plane Arrays Manijeh Razeghi, Edward Kwei-wei Huang, Binh-Minh Nguyen, Siamak Abdollahi Pour, and Pierre-Yves Delaunay SPIE Proceedings, Infrared Technology and Applications XXXVI, Vol. 7660, pp. 76601F-- May 10, 2010 ...[Visit Journal] In recent years, the Type-II superlattice (T2SL) material platform has seen incredible growth in the understanding of its material properties which has lead to unprecedented development in the arena of device design. Its versatility in band-structure engineering is perhaps one of the greatest hallmarks of the T2SL that other material platforms are lacking. In this paper, we discuss advantages of the T2SL, specifically the M-structure T2SL, which incorporates AlSb in the traditional InAs/GaSb superlattice. Using the M-structure, we present a new unipolar minority electron detector coined as the p-M-p, the letters which describe the composition of the device. Demonstration of this device structure with a 14 μm cutoff attained a detectivity of 4x10¹⁰ Jones (-50 mV) at 77 K. As device performance improves year after year with novel design contributions from the many researchers in this field, the natural progression in further enabling the ubiquitous use of this technology is to reduce cost and support the fabrication of large infrared imagers. In this paper, we also discuss the use of GaAs substrates as an enabling technology for third generation imaging on T2SLs. Despite the 7.8% lattice mismatch between the native GaSb and alternative GaAs substrates, T2SL photodiodes grown on GaAs at the MWIR and LWIR have been demonstrated at an operating temperature of 77 K [reprint (PDF)]
16.	Sb-based infrared materials and photodetectors for the near room temperature applications J.D. Kim, E. Michel, H. Mohseni, J. Wojkowski, J.J. Lee and M. Razeghi SPIE Conference, San Jose, CA, Vol. 2999, pp. 55-- February 12, 1997 ...[Visit Journal] We report on the growth of InSb, InAsSb, and InTlSb alloys for infrared photodetector applications. The fabrication and characterization of photodetectors based on these materials are also reported. Both photoconductive and photovoltaic devices are investigated. The materials and detector structures were grown on (100) and (111)B semi-insulating GaAs and GaAs coated Si substrates by low pressure metalorganic chemical vapor deposition and solid source molecular beam epitaxy. Photoconductive detectors fabricated from InAsSb and InTlSb have been operated in the temperature range from 77 K to 300 K. The material parameters for photovoltaic device structures have been optimized through theoretical calculations based on fundamental mechanisms. InSb p-i-n photodiodes with 77 K peak responsivities approximately 103 V/W were grown on Si and (111) GaAs substrates. An InAsSb photovoltaic detector with a composition of x equals 0.85 showed photoresponse up to 13 micrometers at 300 K with a peak responsivity of 9.13 X 10-2 V/W at 8 micrometers . The RoA product of InAsSb detectors has been theoretically and experimentally analyzed. [reprint (PDF)]
16.	Demonstration of mid-wavelength infrared nBn photodetectors based on type-II InAs/InAs_1-xSb_x superlattice grown by metal-organic chemical vapor deposition Donghai Wu, Arash Dehzangi, and Manijeh Razeghi Appl. Phys. Lett. 115, 061102-- August 6, 2019 ...[Visit Journal] We report design, growth, and characterization of midwavelength infrared nBn photodetectors based on a type-II InAs/InAs_1-xSb_x superlattice on a GaSb substrate grown by metal-organic chemical vapor deposition. An InAs/AlAs_1-ySb_y/InAs/InAs_1-xSb_x superlattice design was used as the large bandgap electron barrier in the photodetectors. At 150 K, the photodetector exhibits a peak responsivity of 1.23 A/W, corresponding to a quantum efficiency of 41% at an applied bias voltage of −100 mV under front-side illumination, with a 50% cut-off wavelength of 4.6 μm. With an R × A of 356 Ω·cm² and a dark current density of 1.6 × 10⁻⁴ A/cm² under an applied bias of −100 mV at 150 K, the photodetector exhibits a specific detectivity of 1.4 × 10¹¹ cm·Hz^1/2/W. [reprint (PDF)]
16.	Temperature dependence of threshold current density J_th and differential efficiency of High Power InGaAsP/GaAs ( λ = 0.8 μm) lasers H. Yi, J. Diaz, I. Eliashevich, M. Stanton, M. Erdtmann, X. He, L. Wang, and M. Razeghi Applied Physics Letters 66 (3)-- January 16, 1995 ...[Visit Journal] An experimental and theoretical study on temperature dependence of the threshold current density J_th and differential efficiency ηd for the InGaAsP/GaAs laser diodes emitting at λ=0.8 μm was performed. Threshold current density J_th increases and differential efficiency η_d decreases as temperature is increased mainly because of thermal broadening of the gain spectrum. However, the measured temperature dependence of J_th and η_d could not be explained when only this effect was considered. In this letter, the temperature dependence of momentum relaxation rate ℏ/τ of carriers was investigated by performing the photoluminescence study. At high temperature, increase of the momentum relaxation rate ℏ/τ leads to reduction of the gain and mobility and increase of the optical loss, causing higher J_th and lower η_d as experimentally observed. The resulting theoretical model provides a good explanation for the mechanism of the increase of J_th and decrease of η_d. [reprint (PDF)]
16.	Fabrication of GaN Nanotubular Material using MOCVD with an Aluminium Oxide Membrane W.G. Jung, S.H. Jung, P. Kung, and M. Razeghi Nanotechnology 17-- January 1, 2006 ...[Visit Journal] GaN nanotubular material is fabricated with an aluminium oxide membrane in MOCVD. SEM, XRD, TEM and PL are employed to characterize the fabricated GaN nanotubular material. An aluminium oxide membrane with ordered nanoholes is used as a template. Gallium nitride is deposited at the inner wall of the nanoholes in the aluminium oxide template, and the nanotubular material with high aspect ratio is synthesized using the precursors of TMG and ammonia gas. Optimal synthesis conditions in MOCVD are obtained successfully for the gallium nitride nanotubular material in this research. The diameter of the GaN nanotube fabricated is approximately 200–250 nm and the wall thickness is about 40–50 nm. [reprint (PDF)]
16.	Review of III-Nitride Optoelectronic Materials for light Emission and Detection M. Razeghi, A. Yasan, R. McClintock, K. Mayes, D. Shiell, S. Darvish, and P. Kung Physica Status Solidi C S141 - S148-- September 10, 2004 ...[Visit Journal] We review the significant achievements relating to optoelectronic devices based on III-nitrides at the center for quantum devices (CQD). Based on GaN/InGaN multiple-quantum well structures, we demonstrated blue laser diodes at a wavelength of 405 nm. This achievement was particularly significant at the time, because while no defect reduction technique was used, a fairly low threshold current density was achieved (3.8 kA/cm²). In the past few years, however, the interest has shifted towards shorter wavelength light emitters, i.e. ultraviolet LEDs and LDs. Lower crystalline quality and unsatisfactory doping levels of AlGaN compound semiconductors posed serious challenges en route to the realization of UV light emitters. However, steady progress in the growth of AlGaN and AlN epilayers made it possible to overcome some of the difficulties. To date, we have been able to demonstrate UV LEDs at wavelengths as short as 265 nm (corresponding to 45% Al in Al_xGa_1-xN) with optical output powers of over 5 mW. We have addressed the n-type AlGaN doping problem by using a Si-In co-doped scheme. We also employed high-quality AlGaN/AlN superlattice templates for the reduction of defects. We have also demonstrated 280 nm UV LEDs with output powers of over 6 mW and external quantum efficiencies of over 0.25%. Despite all the success in the realization of short-wavelength UV LEDs, UV laser diodes at these short wavelengths are yet to be realized. The main difficulties are the low material quality, high device resistance leading to excessive heating of the device, realization of smooth cavity mirrors, and issues related to the cracking of the material. We have also demonstrated different types of photodetectors in the UV range of the spectrum: photoconductors, MSM photodetector, Schottky barrier photodetectors, and p-i-n photodiodes to name a few. The most promising type of photodetector for realization of UV imaging focal plane arrays is the p-i-n photodiode. Realization of high-efficiency AlGaN-based p-i-n photodiodes becomes more difficult when considering the need for the collection of the light from the backside of the substrate. However, similar to our back-emission UV LED structure, we have demonstrated back-illuminated p-i-n solar-blind photodiodes with external quantum efficiencies as high as 68% under no applied bias and 74% under -5 V of bias. [reprint (PDF)]
16.	Characterization of InTlSb/InSb Grown by Low Pressure Metalorganic Chemical Vapor Deposition on GaAs Substrat Y.H. Choi, P. Staveteig, E. Bigan, and M. Razeghi Journal of Applied Physics 75 (6)-- March 15, 1994 ...[Visit Journal] Optical properties of InTlSb, a new long wavelength infrared material, are investigated. InTlSb/InSb epilayers grown by low‐pressure metal‐organic chemical vapor deposition on semi‐insulating GaAs substrates were characterized using Auger electron spectroscopy and Fourier transform infrared spectroscopy. Auger electron spectra confirm the presence of thallium. Transmission measurements at 77 K indicate an absorption shift from 5.5 μm for InSb up to 8 μm for InTlSb that is confirmed by photoconductivity measurements. [reprint (PDF)]
16.	Generalized k·p perturbation theory for atomic-scale superlattices H. Yi and M. Razeghi Physical Review B 56 (7)-- August 15, 1997 ...[Visit Journal] We present a generalized k⋅p perturbation method that is applicable for atomic-scale superlattices. The present model is in good quantitative agreement with full band theories with local-density approximation, and approaches results of the conventional k⋅p perturbation method (i.e., Kane’s Hamiltonian) with the envelope function approximation for superlattices with large periods. The indirect band gap of AlAs/GaAs superlattices with short periods observed in experiments is explained using this method. [reprint (PDF)]
16.	Room temperature operation of 8-12 μm InSbBi infrared photodetectors on GaAs substrates J.J. Lee, J.D. Kim, and M. Razeghi Applied Physics Letters 73 (5)-- August 3, 1998 ...[Visit Journal] We report the room temperature operation of 8–12 μm InSbBi long-wavelength infrared photodetectors. The InSbBi/InSb heterostructures were grown on semi-insulating GaAs (001) substrates by low pressure metalorganic chemical vapor deposition. The voltage responsivity at 10.6 μm was about 1.9 mV/W at room temperature and the corresponding Johnson noise limited detectivity was estimated to be about 1.2×10⁶ cm·Hz^½/W. The carrier lifetime derived from the voltage dependent responsivity measurements was about 0.7 ns. [reprint (PDF)]
16.	Low pressure metalorganic chemical vapor deposition of InP and related compounds M. Razeghi, M. A. Poisson, J. P. Larivain & J. P. Duchemin Razeghi, M., Poisson, M.A., Larivain, J.P. et al. Low pressure metalorganic chemical vapor deposition of InP and related compounds. J. Electron. Mater. 12, 371–395 (1983). https://doi.org/10.1007/BF02651138-- March 1, 1983 ...[Visit Journal] The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga0.47In0.53 As and GaxIn1-xAsyP1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm2 V−1S−1 at 300 K and 58 900 cm2 V−1 S−1 at 772K, and for GaInAs was 11900 cm2 V−1 S−1 at 300 K, 54 600 cm2 V−1 S−1 at 77 K and 90 000 cm V−1S−1 at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current. [reprint (PDF)]
16.	Background limited performance of long wavelength infrared focal plane arrays fabricated from M-structure InAs-GaSb superlattices P.Y. Delaunay, B.M. Nguyen, D. Hoffman, E.K. Huang, and M. Razeghi IEEE Journal of Quantum Electronics, Vol. 45, No. 2, p. 157-162.-- February 1, 2009 ...[Visit Journal] The recent introduction of a M-structure design improved both the dark current and R₀A performances of Type-II InAs-GaSb photodiodes. A focal plane array fabricated with this design was characterized at 81 K. The dark current of individual pixels was measured between 1.1 and 1.6 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without antireflective coating was 74%. The noise equivalent temperature difference reached 23 mK, limited only by the performance of the testing system and the read out integrated circuit. Background limited performances were demonstrated at 81 K for a 300 K background. [reprint (PDF)]
16.	GaInAs and GaInAsP materials grown by low pressure MOCVD for microwave and optoelectronic applications J.P. Duchemin, J.P. Hirtz, M. Razeghi, M. Bonnet , S.D. Hersee J.P. Duchemin, J.P. Hirtz, M. Razeghi, M. Bonnet, S.D. Hersee, GaInAs and GaInAsP materials grown by low pressure MOCVD for microwave and optoelectronic applications, Journal of Crystal Growth, Volume 55, Issue 1, 1981, Pages 64-73-- October 1, 1981 ...[Visit Journal] The low pressure MOCVD technique has been successfully used to grow GaInAsP, lattice-matched to InP, for the complete compositional range between InP (λ=0.91 μm) and the ternary compound Ga0.47In0.53As (λ=1.67 μm). By contrast to LPE growth it has been found that during the MOCVD growth of double heterostructures InP can be grown directly onto the ternary or quaternary with no disturbance of the active layer, i.e. there is no effect equivalent to “melt back”. The compositional grading on both sides of the active layer was measured by scanning Auger spectroscopy on bevelled samples. It was found that the graded regions were typically less than 100 Å wide for GaInAsP active layers and less than 50 Å wide for GaInAs active layers. Single layers of undoped GaInAs exhibited a typical mobility of 6700 cm2 V-1s-1 at 1.5×1017 cm-3. The compositional uniformity of the ternary layers was characterised by measurement of the photoluminescence wavelength at various points on a large sample. The wavelength varied by <3 nm over 95% of the area, which was approximately 8 cm2. Our early MOCVD grown GaInAsP/InP DH lasers exhibited high thresholds due to a poor interface between the p-InP and the active layer. However, recently fabricated broad area lasers emitting at 1.27 μm show an average threshold current density of 1.5 kA cm-2 with a T0 of between 70 to 80 K. Stripe geometry lasers have being fabricated from this material and CW operation has been obtained. [reprint (PDF)]
16.	High operability 1024 x 1024 long wavelength infrared focal plane array base on Type-II InAs/GaSb superlattice A. Haddadi, S.R. Darvish, G. Chen, A.M. Hoang, B.M. Nguyen and M. Razeghi AIP Conference Proceedings, Vol. 1416, p. 56-58_NGS15 Conf_Blacksburg, VA_Aug 1-5, 2011-- December 31, 2011 ...[Visit Journal] Fabrication and characterization of a high performance 1024×1024 long wavelength infrared type‐II superlattice focal plane array are described. The FPA performs imaging at a continous rate of 15.00 frames/sec. Each pixel has pitch of 18μm with a fill factor of 71.31%. It demonstrates excellent operability of 95.8% and 97.4% at 81 and 68K operation temperature. The external quantum efficiency is ∼81% without any antireflective coating. Using F∕2 optics and an integration time of 0.13ms, the FPA exhibits an NEDT as low as 27 and 19mK at operating temperatures of 81 and 68K respectively. [reprint (PDF)]
16.	Continuous-wave operation of λ ~ 4.8 µm quantum-cascade lasers at room temperature A. Evans, J.S. Yu, S. Slivken, and M. Razeghi Applied Physics Letters, 85 (12)-- September 20, 2004 ...[Visit Journal] Continuous-wave (cw) operation of quantum-cascade lasers emitting at λ~4.8 µm is reported up to a temperature of 323 K. Accurate control of layer thickness and strain-balanced material composition is demonstrated using x-ray diffraction. cw output power is reported to be in excess of 370 mW per facet at 293 K, and 38 mW per facet at 323 K. Room-temperature average power measurements are demonstrated with over 600 mW per facet at 50% duty cycle with over 300 mW still observed at 100% (cw) duty cycle. [reprint (PDF)]
16.	III-Nitride Optoelectronic Devices: From Ultraviolet Toward Terahertz M. Razeghi IEEE Photonics Journal-Breakthroughs in Photonics 2010, Vol. 3, No. 2, p. 263-267-- April 26, 2011 ...[Visit Journal] We review III-Nitride optoelectronic device technologies with an emphasis on recent breakthroughs. We start with a brief summary of historical accomplishments and then report the state-of-the-art in three key spectral regimes: (1) Ultraviolet (AlGaN-based avalanche photodiodes, single photon detectors, focal plane arrays, and light emitting diodes), (2) Visible (InGaN-based solid state lighting, lasers, and solar cells), and (3) Near-, mid-infrared, and terahertz (AlGaN/GaN-based gap-engineered intersubband devices). We also describe future trends in III-Nitride optoelectronic devices. [reprint (PDF)]
16.	Al_xGa_1-xN-based back-illuminated solar-blind photodetectors with external quantum efficiency of 89% E. Cicek, R. McClintock, C. Y. Cho, B. Rahnema, and M. Razeghi Appl. Phys. Lett. 103, 191108 (2013)-- November 5, 2013 ...[Visit Journal] We report on high performance Al_xGa_1−xN-based solar-blind ultraviolet photodetector (PD) array grown on sapphire substrate. First, high quality, crack-free AlN template layer is grown via metalorganic chemical vapor deposition. Then, we systematically optimized the device design and material doping through the growth and processing of multiple devices. After optimization, uniform and solar-blind operation is observed throughout the array; at the peak detection wavelength of 275 nm, 729 μm² area PD showed unbiased peak external quantum efficiency and responsivity of ∼80% and ∼176 mA/W, respectively, increasing to 89% under 5 V of reverse bias. Taking the reflection loses into consideration, the internal quantum efficiency of these optimized PD can be estimated to be as high as ∼98%. The visible rejection ratio measured to be more than six orders of magnitude. Electrical measurements yielded a low-dark current density: <2 × 10⁻⁹ A/cm², at 10 V of reverse bias. [reprint (PDF)]
16.	Photovoltaic effects in GaN structures with p-n junction X. Zhang, P. Kung, D. Walker, J. Piotrowski, A. Rogalski, A. Saxler, and M. Razeghi Applied Physics Letters 67 (14)-- October 2, 1995 ...[Visit Journal] Large-area GaN photovoltaic structures with p-n junctions have been fabricated using atmospheric pressure metalorganic chemical vapor deposition. The photovoltaic devices typically exhibit selective spectral characteristics with two narrow peaks of opposite polarity. This can be related to p-n junction connected back‐to‐back with a Schottky barrier. The shape of the spectral characteristic is dependent on the thickness of the n- and p-type regions. The diffusion length of holes in the n-type GaN region, estimated by theoretical modeling of the spectral response shape, was about 0.1 μm. [reprint (PDF)]
16.	Performance characteristics of high-purity mid-wave and long-wave infrared type-II InAs/GaSb superlattice infrared photodiodes A. Hood, M. Razeghi, V. Nathan and M.Z. Tidrow SPIE Conference, San Jose, CA, Vol. 6127, pp. 61270U-- January 23, 2006 ...[Visit Journal] The authors report on recent advances in the development of mid-, long-, and very long-wavelength infrared (MWIR, LWIR, and VLWIR) Type-II InAs/GaSb superlattice infrared photodiodes. The residual carrier background of binary Type-II InAs/GaSb superlattice photodiodes of cut-off wavelengths around 5 µm has been studied in the temperature range between 10 and 200 K. A four-point, capacitance-voltage technique on mid-wavelength and long-wavelength Type-II InAs/GaSb superlattice infrared photodiodes reveal residual background concentrations around 5×10¹⁴ cm^-3. Additionally, recent progress towards LWIR photodiodes for focal plane array imaging applications is presented. [reprint (PDF)]
16.	Surface leakage reduction in narrow band gap type-II antimonide-based superlattice photodiodes E.K. Huang, D. Hoffman, B.M. Nguyen, P.Y. Delaunay and M. Razeghi Applied Physics Letters, Vol. 94, No. 5, p. 053506-1-- February 2, 2009 ...[Visit Journal] Inductively coupled plasma (ICP) dry etching rendered structural and electrical enhancements on type-II antimonide-based superlattices compared to those delineated by electron cyclotron resonance (ECR) with a regenerative chemical wet etch. The surface resistivity of 4×10⁵ Ω·cm is evidence of the surface quality achieved with ICP etching and polyimide passivation. By only modifying the etching technique in the fabrication steps, the ICP-etched devices with a 9.3 µm cutoff wavelength revealed a diffusion-limited dark current density of 4.1×10⁻⁶ A/cm² and a maximum differential resistance at zero bias in excess of 5300 Ω·cm² at 77 K, which are an order of magnitude better in comparison to the ECR-etched devices. [reprint (PDF)]
16.	Current status and potential of high power mid-infrared intersubband lasers S. Slivken, Y. Bai, B. Gokden, S.R. Darvish and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 76080B-1-- January 22, 2010 ...[Visit Journal] Some of the recent advances in high power quantum cascade laser development will be reviewed in this paper. Research areas explored include short wavelength (λ <4 µm) lasers, high performance strain-balanced heterostructures, and high power long wavelength (7< λ< 16 µm) lasers. Near λ=4.5 µm, highlights include demonstration of 18% continuous wave wallplug efficiency at room temperature, 53% pulsed wallplug efficiency at 40 K, and 120 W of peak power output from a single device at room temperature. Near λ ~10 µm, up to 0.6 W of continuous output power at room temperature has also been demonstrated, with pulsed efficiencies up to 9%. [reprint (PDF)]
16.	Advances in UV sensitive visible blind GaN-based APDs M. Ulmer, R. McClintock and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-27, 2011), Vol. 7945, p. 79451G-- January 23, 2011 ...[Visit Journal] In this paper, we describe our current state-of-the-art process of making visible-blind APDs based on GaN. We have grown our material on both conventional sapphire and low dislocation density free-standing c- and m-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs are compared. The spectral response and Geiger-mode photon counting performance of UV APDs are studied under low photon fluxes. Single photon detection capabilities with over 30% are demonstrated. We show how with pulse height discrimination the Geiger-mode operation conditions can be optimized for enhanced SPDE versus dark counts. [reprint (PDF)]
16.	Highly selective two-color mid-wave and long-wave infrared detector hybrid based on Type-II superlattices E.K. Huang, M.A. Hoang, G. Chen, S.R. Darvish, A. Haddadi, and M. Razeghi Optics Letters, Vol. 37, No. 22, p. 4744-4746-- November 15, 2012 ...[Visit Journal] 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. [reprint (PDF)]
16.	Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Sourav Adhikary, & Manijeh Razeghi Nature Scientific Reports 7, Article number: 3379-- June 13, 2017 ...[Visit Journal] 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/InAs_1−xSb_x T2SLs have been shown to have a significantly longer minority carrier lifetime. However, demonstration of high–performance dual–band photodetectors based on InAs/InAs_1−xSb_x 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/InAsSb/AlAsSb 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. [reprint (PDF)]
16.	Very high quantum efficiency in type-II InAs/GaSb superlattice photodiode with cutoff of 12 µm B.M. Nguyen, D. Hoffman, Y. Wei, P.Y. Delaunay, A. Hood and M. Razeghi Applied Physics Letters, Vol. 90, No. 23, p. 231108-1-- June 4, 2007 ...[Visit Journal] The authors report the dependence of the quantum efficiency on device thickness of Type-II InAs/GaSb superlattice photodetectors with a cutoff wavelength around 12 µm. The quantum efficiency and responsivity show a clear delineation in comparison to the device thickness. An external single-pass quantum efficiency of 54% is obtained for a 12 µm cutoff wavelength photodiodes with a -region thickness of 6.0 µm. The R₀A value is kept stable for the range of structure thicknesses allowing for a specific detectivity (2.2×10¹¹ cm·Hz^½/W). [reprint (PDF)]
16.	Growth and characterization of InSbBi for long wavelength infrared photodetectors J.J. Lee, J.D. Kim, and M. Razeghi Applied Physics Letters 70 (24)-- June 16, 1997 ...[Visit Journal] The epitaxial growth of InSbBi ternary alloys by low-pressure metalorganic chemical vapor deposition is reported on. X-ray diffraction spectra showed well resolved peaks of InSbBi and InSb films. Bi incorporation was confirmed by energy dispersive x-ray analysis. Photoresponse spectrum up to 9.3 μm which corresponds to 0.13 eV energy band gap has been measured in a sample with Bi composition of 5.8 at.% at 77 K. Electron mobility at room temperature ranges from 44 100 to 4910 cm²/V·s as Bi composition increases. [reprint (PDF)]

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