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2.  Deep ultraviolet (254 nm) focal plane array
E. Cicek, Z. Vashaei, R. McClintock, and M. Razeghi
SPIE Proceedings, Conference on Infrared Sensors, Devices and Applications; and Single Photon Imaging II, Vol. 8155, p. 81551O-1-- August 21, 2011 ...[Visit Journal]
We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A·cm-2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated. [reprint (PDF)]
 
2.  High-performance bias-selectable dual-band Short-/Mid-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb/AlSb Type-II superlattices
M. Razeghi; A.M. Hoang; A. Haddadi; G. Chen; S. Ramezani-Darvish; P. Bijjam; P. Wijewarnasuriy; E. Decuir
Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87041W (June 18, 2013)-- June 18, 2013 ...[Visit Journal]
We report a bias selectable dual-band Type-II superlattice-based short-wave infrared (SWIR) and mid-wave infrared (MWIR) co-located photodetector capable of active and passive imaging. A new double-layer etch-stop scheme is introduced for back-side-illuminated photodetectors, which enhanced the external quantum efficiency both in the SWIR and MWIR spectral regions. Temperature-dependent dark current measurements of pixel-sized 27 μm detectors found the dark current density to be ∼1×10-5 A/cm2 for the ∼4.2 μm cut-off MWIR channel at 140 K. This corresponded to a reasonable imager noise equivalent difference in temperature of ∼49 mK using F/2.3 optics and a 10 ms integration time (tint), which lowered to ∼13 mK at 110 K using and integration time of 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. An excellent imagery from the dual-band imager exemplifying pixel coincidence is shown. [reprint (PDF)]
 
2.  Recent Advances in LWIR Type-II InAs/GaSb Superlattice Photodetectors and Focal Plane Arrays at the Center for Quantum Devices
M. Razeghi, D. Hoffman, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, M.Z. Tidrow, and V. Nathan
IEEE Proceedings, Vol. 97, No. 6, p. 1056-1066-- June 1, 2009 ...[Visit Journal]
In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs, and imaging applications. They now appear to be a possible alternative to the state-of-the-art HgCdTe (MCT) technology in the long and very long wavelength infrared regimes. At the Center for Quantum Devices, we have successfully realized very high quantum efficiency, very high dynamic differential resistance R0A - product LWIR Type – II InAs/GaSb superlattice photodiodes with efficient surface passivation techniques. The demonstration of high quality LWIR Focal Plane Arrays that were 100 % fabricated in - house reaffirms the pioneer position of this university-based laboratory. [reprint (PDF)]
 
2.  Background limited performance of long wavelength infrared focal plane arrays fabricated from type-II InAs/GaSb M-structure superlattice
P.Y. Delaunay, B.M. Nguyen and M. Razeghi
SPIE Porceedings, Vol. 7298, Orlando, FL 2009, p. 72981Q-- April 13, 2009 ...[Visit Journal]
Recent advances in growth techniques, structure design and processing have lifted the performance of Type-II InAs/GaSb superlattice photodetectors. The introduction of a M-structure design improved both the dark current and R0A of Type-II photodiodes. This new structure combined with a thick absorbing region demonstrated background limited performance at 77K for a 300K background and a 2-π field of view. A focal plane array with a 9.6 μm 50% cutoff wavelength was fabricated with this design and characterized at 80K. The dark current of individual pixels was measured around 1.3 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 anti-reflective coating was 72%. The noise equivalent temperature difference reached 23 mK. The deposition of an anti-reflective coating improved the NEDT to 20 mK and the quantum efficiency to 89%. [reprint (PDF)]
 
2.  Demonstration of a 256x256 Middle-Wavelength Infrared Focal Plane Array based on InGaAs/InGaP Quantum Dot Infrared Photodetectors (QDIPs)
J. Jiang, K. Mi, S. Tsao, W. Zhang, H. Lim, T.O'Sullivan, T. Sills, M. Razeghi, G.J. Brown, and M.Z. Tidrow
Applied Physics Letters, 84 (13)-- April 29, 2004 ...[Visit Journal]
We report a demonstration of an infrared focal plane array based on InGaAs/InGaP quantum dot infrared photodetectors. The middle-wavelength infrared quantum-dot infrared photodetector (QDIP) structure was grown via low-pressure metal organic chemical vapor deposition. A detectivity of 3.6×1010 cm·Hz½/W was achieved at T = 95 K and a bias of –1.4 V. The background limited temperature of our QDIP was 140 K with a 45° field of view. A 256×256 detector array was fabricated with dry etching, and hybridized to a Litton readout chip by indium bumps. Thermal imaging was achieved at temperatures up to 120 K. At T = 77 K, the noise equivalent temperature difference was measured as 0.509 K with a 300 K background and f/2.3 optics. [reprint (PDF)]
 
2.  Passivation of type-II InAs/GaSb double heterostructure
P.Y. Delaunay, A. Hood, B.M. Nguyen, D. Hoffman, Y. Wei, and M. Razeghi
Applied Physics Letters, Vol. 91, No. 9, p. 091112-1-- August 27, 2007 ...[Visit Journal]
Focal plane array fabrication requires a well passivated material that is resistant to aggressive processes. The authors report on the ability of type-II InAs/GaSb superlattice heterodiodes to be more resilient than homojunctions diodes in improving sidewall resistivity through the use of various passivation techniques. The heterostructure consisting of two wide band gap (5 µm) superlattice contacts and a low band gap active region (11 µm) exhibits an R0A averaging of 13·Ω cm2. The devices passivated with SiO2, Na2S and SiO2 or polyimide did not degrade compared to the unpassivated sample and the resistivity of the sidewalls increased to 47 kΩ·cm. [reprint (PDF)]
 
2.  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)]
 
2.  Demonstration of a 256x256 Middle-Wavelength Infrared Focal Plane Array based on InGaAs/InGaP Quantum Dot Infrared Photodetectors (QDIPs)
J. Jiang, K. Mi, S. Tsao, W. Zhang, H. Lim, T.O'Sullivan, T. Sills, M. Razeghi, G.J. Brown, and M.Z. Tidrow
Virtual Journal of Nanoscale Science and Technology 9 (13)-- April 5, 2004 ...[Visit Journal][reprint (PDF)]
 
2.  Characteristics of Self-Assembled InGaAs/InGaP Quantum Dot Mid-Infrared Photoconductive Detectors Grown by Low Pressure MOCVD
S. Kim, M. Erdtmann, and M. Razeghi
SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal]
We report the first self-assembled InGaAs/InGaP quantum dot intersubband infrared photoconductive detectors (QDIPs) grown on semi-insulating GaAs substrate by low pressure metal organic chemical vapor deposition (MOCVD). The InGaAs quantum dots were constructed on an InGaP matrix as self assembling in Stranski-Krastanow growth mode in optimum growth conditions. The detector structure was prepared for single layer and multi-stacked quantum dots for active region. Normal incident photoconductive response was observed at a peak wavelength of 5.5 μm with a high responsivity of 130 mA/W, and a detectivity of 4.74 X 107 cm·Hz½/W at 77 K for multi-stack QDIP. Low temperature photoresponse of the single quantum dot photodetector was characterized. Peak response was obtained between 16 K and 60 K. The detailed dark current noise measurements were carried on single and multistack quantum dot infrared detectors. High photoconductive gain as 7.6 x 103 biased at 0.5 V results in increasing the intersubband carrier relaxation time as two order of magnitude compared quantum well infrared photodetectors. [reprint (PDF)]
 
2.  Low irradiance background limited type-II superlattice MWIR M-barrier imager
E.K. Huang, S. Abdollahi Pour, M.A. Hoang, A. Haddadi, M. Razeghi and M.Z. Tidrow
OSA Optics Letters (OL), Vol. 37, No. 11, p. 2025-2027-- June 1, 2012 ...[Visit Journal]
We report a type-II superlattice mid-wave infrared 320 × 256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ∼99%operability. The 280 K blackbody’s photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ∼5 × 1012 ph·cm−2·s−1. Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ∼5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ∼5 × 1010 ph·cm−2·s−1 and temperature sensitivity of 9 mK with F∕2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array’s uniform responsivity. [reprint (PDF)]
 
2.  Chemical lift-off and direct wafer bonding of GaN/InGaN P-I-N structures grown on ZnO
K. Pantzas, D.J. Rogers, P. Bove, V.E. Sandana, F.H. Teherani, Y. El Gmili, M. Molinari, G. Patriarche, L. Largeau, O. Mauguin, S. Suresh, P.L. Voss, M. Razeghi, A. Ougazzaden
Journal of Crystal Growth -- November 7, 2015 ...[Visit Journal]
p-GaN/i-InGaN/n-GaN (PIN) structures were grown epitaxially on ZnO-buffered c-sapphire substrates by metal organic vapor phase epitaxy using the industry standard ammonia precursor for nitrogen. Scanning electron microscopy revealed continuous layers with a smooth interface between GaN and ZnO and no evidence of ZnO back-etching. Energy Dispersive X-ray Spectroscopy revealed a peak indium content of just under 5at% in the active layers. The PIN structure was lifted off the sapphire by selectively etching away the ZnO buffer in an acid and then direct bonded onto a glass substrate. Detailed high resolution transmission electron microscopy and grazing incidence X-ray diffraction studies revealed that the structural quality of the PIN structures was preserved during the transfer process. [reprint (PDF)]
 
2.  Demonstration of 256x256 Focal Plane Arrays Based on Al-free GaInAs/InP QWIP
J. Jiang, K. Mi, R. McClintock, M. Razeghi, G.J. Brown, and C. Jelen
IEEE Photonics Technology Letters 15 (9)-- September 1, 2003 ...[Visit Journal]
We report the first demonstration of an infrared focal plane array based on aluminum-free GaInAs-InP quantum-well infrared photodetectors (QWIPs).A unique positive lithography method was developed to perform indium-bump liftoff. The noise equivalent differential temperature (NEΔT) of 29 mK was achieved at 70 K with f/2 optics. [reprint (PDF)]
 
2.  Temperature dependent characteristics of λ ~ 3.8 µm room-temperature continuous-wave quantum-cascade lasers
J.S. Yu, A. Evans, S. Slivken, S.R. Darvish and M. Razeghi
Applied Physics Letters, 88 (25)-- June 19, 2006 ...[Visit Journal]
The highest-performance device displays pulsed laser action at wavelengths between 3.4 and 3.6 μm, for temperatures up to 300 K, with a low temperature (80 K) threshold current density of approximately 2.6 kA/cm2, and a characteristic temperature of T0~130 K. The shortest wavelength QCL (λ ~ 3.05 μm) has a higher threshold current density (~12 kA/cm2 at T=20 K) and operates in pulsed mode at temperatures up to 110 K. [reprint (PDF)]
 
2.  Gain and recombination dynamics of quantum-dot infrared photodetecto
H. Lim, B. Movaghar, S. Tsao, M. Taguchi, W. Zhang, A.A. Quivy, and M. Razeghi
Virtual Journal of Nanoscale Science & Technology-- December 4, 2006 ...[Visit Journal][reprint (PDF)]
 
2.  Scale-up of the Chemical Lift-off of (In)GaN-based p-i-n Junctions from Sapphire Substrates Using Sacrificial ZnO Template Layers
D. J. Rogers, S. Sundaram, Y. El Gmili, F. Hosseini Teherani, P. Bove, V. Sandana, P. L. Voss, A. Ougazzaden, A. Rajan, K.A. Prior, R. McClintock, & M. Razeghi
Proc. SPIE 9364, Oxide-based Materials and Devices VI, 936424 -- March 24, 2015 ...[Visit Journal]
(In)GaN p-i-n structures were grown by MOVPE on both GaN- and ZnO-coated c-sapphire substrates. XRD studies of the as-grown layers revealed that a strongly c-axis oriented wurtzite crystal structure was obtained on both templates and that there was a slight compressive strain in the ZnO underlayer which increased after GaN overgrowth. The InGaN peak position gave an estimate of 13.6at% for the indium content in the active layer. SEM and AFM revealed that the top surface morphologies were similar for both substrates, with an RMS roughness (5 μm x 5 μm) of about 10 nm. Granularity appeared slightly coarser (40nm for the device grown on ZnO vs 30nm for the device grown on the GaN template) however. CL revealed a weaker GaN near band edge UV emission peak and a stronger broad defect-related visible emission band for the structure grown on the GaN template. Only a strong ZnO NBE UV emission was observed for the sample grown on the ZnO template. Quarter-wafer chemical lift-off (CLO) of the InGaN-based p-i-n structures from the sapphire substrate was achieved by temporary-bonding the GaN surface to rigid glass support with wax and then selectively dissolving the ZnO in 0.1M HCl. XRD studies revealed that the epitaxial nature and strong preferential c-axis orientation of the layers had been maintained after lift-off. This demonstration of CLO scale-up, without compromising the crystallographic integrity of the (In)GaN p-i-n structure opens up the perspective of transferring GaN based devices off of sapphire substrates industrially. [reprint (PDF)]
 
2.  High-Performance Focal Plane Arrays Based on InAs-GaSb Superlattices with a 10-micron Cutoff Wavelegth
P.Y. Delaunay, B.M. Nguyen, D. Hoffman and M. Razeghi
IEEE Journal of Quantum Electronics, Vol. 44, No. 5, p. 462-467-- May 1, 2008 ...[Visit Journal]
We report on the demonstration of a focal plane array based on Type-II InAs/GaSb superlattices grown on N-type GaSb substrate with a 50%-cutoff wavelength at 10 μm. The surface leakage occurring after flip-chip bonding and underfill in the Type-II devices was suppressed using a double heterostructure design. The R0A of diodes passivated with SiO2 was 23 Ω·cm2 after underfill. A focal plane array hybridized to an Indigo readout integrated circuit demonstrated a noise equivalent temperature difference of 33 mK at 81 K, with an integration time of 0.23 ms. [reprint (PDF)]
 
2.  Room-temperature continuous-wave operation of quantum-cascade lasers at λ ~ 4 µm
J.S. Yu, S.R. Darvish, A. Evans, J. Nguyen, S. Slivken, and M. Razeghi
Applied Physics Letters 88 (4)-- January 23, 2006 ...[Visit Journal]
High-power cw λ~4 μm quantum-cascade lasers (QCLs) are demonstrated. The effect of different cavity length and laser die bonding is also investigated. For a high-reflectivity-coated 11-μm-wide and 4-mm-long epilayer-down bonded QCL, cw output powers as high as 1.6 W at 80 K and 160 mW at 298 K are obtained, and the cw operation is achieved up to 313 K with 12 mW. [reprint (PDF)]
 
2.  Growth and Characterization of Long-Wavelength Infrared Type-II Superlattice Photodiodes on a 3-in GaSb Wafer
B.M. Nguyen, G. Chen, M.A. Hoang, and M. Razeghi
IEEE Journal of Quantum Electronics (JQE), Vol. 47, No. 5, May 2011, p. 686-690-- May 11, 2011 ...[Visit Journal]
We report the molecular beam epitaxial growth and characterization of high performance Type-II superlattice photodiodes on 3” GaSb substrates for long wavelength infrared detection. A 7.3 micron thick device structure shows excellent structural homogeneity via atomic force microscopy and x-ray diffraction characterization. Optical and electrical measurements of photodiodes reveal not only the uniformity of the Type-II superlattice material but also of the fabrication process. Across the wafer, at 77 K, photodiodes with a 50% cut-off wavelength of 11 micron exhibit more than 45% quantum efficiency, and a dark current density of 1.0 x 10-4 A/cm² at 50 mV, resulting in a specific detectivity of 6x1011 cm·Hz1/2/W. [reprint (PDF)]
 
2.  Gain and recombination dynamics of quantum-dot infrared photodetectors
H. Lim, B. Movaghar, S. Tsao, M. Taguchi, W. Zhang, A.A. Quivy, and M. Razeghi
Physical Review B, 74 (20)-- November 15, 2006 ...[Visit Journal]
In this paper we present a theory of diffusion and recombination in QDIPs which is an attempt to explain the recently reported values of gain in these devices. We allow the kinetics to encompass both the diffusion and capture rate limited regimes of carrier relaxation using rigorous random walk and diffusion methods. The photoconductive gains are calculated and compared with the experimental values obtained from InGaAs/InGaP/GaAs and InAs/InP QDIPs using the generation-recombination noise analysis. [reprint (PDF)]
 
2.  Multi-color 4–20 μm In-P-based Quantum Well Infrared Photodetectors
C. Jelen, S. Slivken, G.J. Brown, and M. Razeghi
SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal]
In order to tune the wavelength of lattice-matched QWIP detectors over the range from 4 - 20 &mum, new designs are demonstrated for the first time which combine InGaAlAs and InGaAsP layers lattice-matched to InP and grown by gas-source molecular beam epitaxy. We demonstrate the first long-wavelength quantum well infrared photodetectors using the lattice-matched n-doped InGaAlAs/InP materials system. Samples with AlAs mole fractions of 0.0, 0.1, and 0.15 result in cutoff wavelengths of 8.5, 13.3, and 19.4 μm, respectively. A 45 degree facet coupled illumination responsivity of R equals 0.37 A/W and detectivity of D*(λ) equals 1x109 cm·Hz½·W-1 at T = 77 K, for a cutoff wavelength λc equals 13.3 μm have been achieved. Based on the measured intersubband photoresponse wavelength, a null conduction band offset is expected for In0.52Ga0.21Al0.27As/InP heterojunctions. We also report quantum well infrared photodetector structures of In0.53Ga0.47As/Al0.48In0.52As grown on InP substrate with photoresponse at 4 μm suitable for mid-wavelength infrared detectors. These detectors exhibit a constant peak responsivity of 30 mA/W independent of temperature in the range from T equals 77 K to T equals 200 K. Combining these two materials, we report the first multispectral detectors that combine lattice-matched quantum wells of InGaAs/InAlAs and InGaAs/InP. Utilizing two contacts, a voltage tunable detector with (lambda) p equals 8 micrometer at a bias of V equals 5 V and λp equals 4 μm at V equals 10 V is demonstrated. [reprint (PDF)]
 
2.  Surface leakage investigation via gated type-II InAs/GaSb long-wavelength infrared photodetectors
G. Chen, E.K. Huang, A.M. Hoang, S. Bogdanov, S.R. Darvish, and M. Razeghi
Applied Physics Letters, Vol. 101, No. 21, p. 213501-1-- November 19, 2012 ...[Visit Journal]
By using gating technique, surface leakage generated by SiO2 passivation in long-wavelength infrared type-II superlattice photodetector is suppressed, and different surface leakage mechanisms are disclosed. By reducing the SiO2 passivation layer thickness, the saturated gated bias is reduced to −4.5 V. At 77 K, dark current densities of gated devices are reduced by more than 2 orders of magnitude, with 3071 Ω·cm² differential-resistance-area product at −100 mV. With quantum efficiency of 50%, the 11 μm 50% cut-off gated photodiode has a specific detectivity of 7 × 1011 Jones, and the detectivity stays above 2 × 1011 Jones from 0 to −500 mV operation bias. [reprint (PDF)]
 
2.  Ultra-broadband quantum cascade laser, tunable over 760 cm−1, with balanced gain
N. Bandyopadhyay, M. Chen, S. Sengupta, S. Slivken, and M. Razeghi
Opt. Express 23, 21159-21164 -- August 10, 2015 ...[Visit Journal]
A heterogeneous quantum cascade laser, consisting of multiple stacks of discrete wavelength quantum cascade stages, emitting in 5.9-10.9 µm, wavelength range is reported. The broadband characteristics are demonstrated with a distributed-feedback laser array, emitting at fixed frequencies at room temperature, covering an emission range of ~760 cm−1, which is ~59% relative to the center frequency. By appropriate choice of a strained AlInAs/GaInAs material system, quantum cascade stage design and spatial arrangement of stages, the distributed-feedback array has been engineered to exhibit a flat threshold current density across the demonstrated range. [reprint (PDF)]
 
2.  Self-assembled semiconductor quantum dot infrared photodetector operating at room temperature and focal plane array
Ho-Chul Lim; Stanley Tsao; Wei Zhang; Manijen Razeghi
Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 65420R (May 14, 2007)-- May 14, 2007 ...[Visit Journal]
Self-assembled semiconductor quantum dots have attracted much attention because of their novel properties and thus possible practical applications including the lasers, detectors and modulators. Especially the photodetectors which have quantum dots in their active region have been developed and show promising performances such as high operation temperature due to three dimensional confinement of the carriers and normal incidence in contrast to the case of quantum well detectors which require special optical coupling schemes. Here we report our recent results for mid-wavelength infrared quantum dot infrared photodetector grown by low-pressure metalorganic chemical vapor deposition. The material system we have investigated consists of 25 period self-assembled InAs quantum dot layers on InAlAs barriers, which are lattice-matched to InP substrates, covered with InGaAs quantum well layers and InAlAs barriers. This active region was sandwiched by highly doped InP contact layers. The device operates at 4.1 μm with a peak detectivity of 2.8×1011 cm·Hz1/2/W at 120 K and a quantum efficiency of 35 %. The photoresponse can be observed even at room temperature resulting in a peak detectivity of 6×107 cm·Hz1/2/W. A 320×256 focal plane array has been fabricated in this kind of device. Its performance will also be discussed here. [reprint (PDF)]
 
2.  Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs1−xSbx type-II superlattices
A. Haddadi, R. Chevallier, G. Chen, A. M. Hoang, and M. Razeghi
Applied Physics Letters 106 , 011104 (2015)-- January 8, 2015 ...[Visit Journal]
A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm² under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm·Hz½·W-1 at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm² under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm·Hz½·W-1. [reprint (PDF)]
 
2.  InGaAs/InGaP Quantum-Dot Photodetector with a High Detectivity
H. Lim, S. Tsao, M. Taguchi, W. Zhang, A. Quivy and M. Razeghi
SPIE Conference, San Jose, CA, Vol. 6127, pp. 61270N-- January 23, 2006 ...[Visit Journal]
Quantum-dot infrared photodetectors (QDIPs) have recently been considered as strong candidates for numerous applications such as night vision, space communication, gas analysis and medical diagnosis involving middle and long wavelength infrared (MWIR and LWIR respectively) operation. This is due to their unique properties arising from their 3-dimensional confinement potential that provides a discrete density of states. They are expected to outperform quantum-well infrared photodetectors (QWIPs) as a consequence of their natural sensitivity to normal incident radiation, their higher responsivity and their higher-temperature operation. So far, most of the QDIPs reported in the literature were based on the InAs/GaAs system and were grown by molecular beam epitaxy (MBE). Here, we report on the growth of a high detectivity InGaAs/InGaP QDIP grown on a GaAs substrate using low-pressure metalorganic chemical vapor deposition (MOCVD). [reprint (PDF)]
 

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