Center for Quantum Devices - Most Downloaded Journal Articles

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2.	High power operation of λ ∼ 5.2–11 μm strain balanced quantum cascade lasers based on the same material composition N. Bandyopadhyay, Y. Bai, S. Slivken, and M. Razeghi Appl. Phys. Lett. 105, 071106 (2014)-- August 20, 2014 ...[Visit Journal] A technique based on composite quantum wells for design and growth of strain balanced Al_0.63In_0.37As/Ga_0.35In_0.65As/Ga_0.47In_0.53As quantum cascade lasers (QCLs) by molecular beam epitaxy (MBE), emitting in 5.2–11 μm wavelength range, is reported. The strained Al_0.63In_0.37As provides good electron confinement at all wavelengths, and strain balancing can be achieved through composite wells of Ga_0.35In_0.65As/Ga_0.47In_0.53As for different wavelength. The use of these fixed composition materials can avoid the need for frequent calibration of a MBE reactor to grow active regions with different strain levels for different wavelengths. Experimental results for QCLs emitting at 5.2, 6.7, 8.2, 9.1, and 11 μm exhibit good wall plug efficiencies and power across the whole wavelength range. It is shown that the emission wavelength can be predictably changed using the same design template. These lasers are also compatible with a heterogeneous broadband active region, consisting of multiple QCL cores, which can be produced in a single growth run. [reprint (PDF)]
2.	Near milliwatt power AlGaN-based ultraviolet light emitting diodes based on lateral epitaxial overgrowth of AlN on Si(111) Y. Zhang, S. Gautier, C. Cho, E. Cicek, Z, Vashaei, R. McClintock, C. Bayram, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 102, No. 1, p. 011106-1-- January 7, 2013 ...[Visit Journal] We report on the growth, fabrication, and device characterization of AlGaN-based thin-film ultraviolet (UV) (λ ∼ 359 nm) light emitting diodes (LEDs). First, AlN/Si(111) template is patterned. Then, a fully coalesced 7-μm-thick lateral epitaxial overgrowth (LEO) of AlN layer is realized on patterned AlN/Si(111) template followed by UV LED epi-regrowth. Metalorganic chemical vapor deposition is employed to optimize LEO AlN and UV LED epitaxy. Back-emission UV LEDs are fabricated and flip-chip bonded to AlN heat sinks followed by Si(111) substrate removal. A peak pulsed power and slope efficiency of ∼0.6 mW and ∼1.3 μW/mA are demonstrated from these thin-film UV LEDs, respectively. For comparison, top-emission UV LEDs are fabricated and back-emission LEDs are shown to extract 50% more light than top-emission ones. [reprint (PDF)]
2.	Al_xGa_1-xN p-i-n Photodiodes on Sapphire Substrates D. Walker, P. Kung, P. Sandvik, J. Wu, M. Hamilton, I.H. Lee, J. Diaz, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] We report the fabrication and characterization of Al_xGa1-xN p-i-n photodiodes (0.05 ≤ to X ≤ 0.30) grown on sapphire by low-pressure metalorganic chemical vapor deposition. The devices present a visible-rejection of about four orders of magnitude with a cutoff wavelength that shifts from 350 nm to 291 nm. They also exhibit a constant responsivity for five decades (30 mW/m² to 1 kW/m²) of optical power density. Using capacitance measurements, the values for the acceptor concentration in the p-Al_xGa_1-xN region and the unintentional donor concentration in the intrinsic region are found. Photocurrent decays are exponential for high load resistances, with a time constant that corresponds to the RC product of the system. For low load resistances the transient response becomes non-exponential, with a decay time longer than the RC constant. [reprint (PDF)]
2.	Aluminum-free Quantum Well Intersubband Photodetectors with p-type GaAs Wells and lattice-matched ternary and quaternary barriers J. Hoff, E. Bigan, G.J. Brown, and M. Razeghi Optoelectronic Integrated Circuit Materials, Physics and Devices, SPIE Conference, San Jose, CA; Proceedings, Vol. 2397-- February 6, 1995 ...[Visit Journal] Acceptor doped Quantum Well Intersubband Photodetectors with GaAs wells and lattice matched barriers of both ternary (In_0.49Ga_0.51P) and quaternary (In_0.62Ga_0.38As_0.22P_0.78) materials have been grown on semi-insulating GaAs substrates by Low Pressure Metal Organic Chemical Vapor Deposition. Mesa devices were fabricated and subjected to a series of tests to illuminate experimentally some of the detection capabilities of the lattice matched quaternary InxGa1-xAsyP1-y system with (0 ≤ x ≤ 0.52) and (0 ≤ y ≤ 1). The observed photoresponse cut-off wavelengths are in good agreement with the activation energies observed in the temperature dependence of the dark currents. Kronig-Penney calculations were used to model the intersubband transition energies. [reprint (PDF)]
2.	Defects in Organometallic Vapor-Phase Epitaxy-Grown GaInP Layers Feng S.L., Bourgoin J.C., Omnes F., and Razeghi M. Applied Physics Letters 59 (8), p. 941-- May 28, 1991 ...[Visit Journal] Non-intentionally doped metalorganic vapor‐phase epitaxy Ga_1−x InxP layers, having an alloy composition (x = 0.49) corresponding to a lattice matched to GaAs, grown by metalorganic chemical vapor deposition, have been studied by capacitance‐voltage and deep-level transient spectroscopy techniques. They are found to exhibit a free‐carrier concentration at room temperature of the order of 10¹⁵ cm⁻³. Two electron traps have been detected. The first one, at 75 meV below the conduction band, is in small concentration (∼10¹³ cm⁻³) while the other, at about 0.9 eV and emitting electrons above room temperature, has a concentration in the range 10¹⁴–10¹⁵ cm⁻³. [reprint (PDF)]
2.	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)]
2.	High power, continuous wave, room temperature operation of λ ~ 3.4 μm and λ ~ 3.55 μm InP-based quantum cascade lasers N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 100, No. 21, p. 212104-1-- May 21, 2012 ...[Visit Journal] We report two highly strain-balanced InP-based AlInAs/GaInAs quantum cascade lasers emitting near 3.39 and 3.56 . A pulsed threshold current density of only 1.1 kA/cm² has been achieved at room temperature for both lasers with characteristic temperatures (T₀) of 166 K and 152 K, respectively. The slope efficiency is also relatively temperature insensitive with characteristic temperatures (T₁) of 116 K and 191 K, respectively. Continuous wave powers of 504 mW and 576 mW are obtained at room temperature, respectively. This was accomplished without buried ridge processing. [reprint (PDF)]
2.	Light People: Professor Manijeh Razeghi Hui Wang, and Cun Yu Light Sci Appl 13, 164 ...[Visit Journal] Editorial The sense of light is the first sensation the human body develops. The importance of light is self-evident. However, we all know that the light we can see and perceive covers only a small section of the spectrum. Today, for Light People, we feature a researcher who is committed to exploring different spectral bands of light ranging from deep ultraviolet to terahertz waves and working on quantum semiconductor technology, Prof. Manijeh Razeghi of the Northwestern University in the United States. Known for her quick thinking and witty remarks, Prof. Razeghi is passionate about life and always kind to others. As a scientist, she does not limit her research to a single focus, instead, she works on the entire process from material selection, device design, processing, and manufacturing, all the way to product application. She has a strong passion for education, a commitment unwavered by fame or fortune. For her students, she is both a reliable source of knowledge and a motherly figure with a caring heart. She firmly believes that all things in nature can give her energy and inspiration. In science, she is a true “pioneer” in research and a “miner” of scientific discoveries. She advises young scientists to enjoy and love what they do, and turn their research into their hobby. As a female scientist, she calls on all women to realize their true value and potential. Next, let’s hear from Professor Manijeh Razeghi, a true star who radiates energy and light [reprint (PDF)]
2.	High quantum efficiency two color type-II InAs/GaSb n-i-p-p-i-n photodiodes P.Y. Delaunay, B.M. Nguyen, D. Hoffman, A. Hood, E.K. Huang, M. Razeghi, and M.Z. Tidrow Applied Physics Letters, Vol. 92, No. 11, p. 111112-1-- March 17, 2008 ...[Visit Journal] A n-i-p-p-i-n photodiode based on type-II InAs/GaSb superlattice was grown on a GaSb substrate. The two channels, with respective 50% of responsivity cutoff wavelengths at 7.7 and 10 µm, presented quantum efficiencies (QEs) of 47% and 39% at 77 K. The devices can be operated as two diodes for simultaneous detection or as a single n-i-p-p-i-n detector for sequential detection. In the latter configuration, the QEs at 5.3 and 8.5 µm were measured as high as 40% and 39% at 77 K. The optical cross-talk between the two channels could be reduced from 0.36 to 0.08 by applying a 50 mV bias. [reprint (PDF)]
2.	High Power 280 nm AlGaN Light Emitting Diodes Based on an Asymmetric Single Quantum Well K. Mayes, A. Yasan, R. McClintock, D. Shiell, S.R. Darvish, P. Kung, and M. Razeghi Applied Physics Letters, 84 (7)-- February 16, 2004 ...[Visit Journal] We demonstrate high-power AlGaN-based ultraviolet light-emitting diodes grown on sapphire with an emission wavelength of 280 nm using an asymmetric single-quantum-well active layer configuration on top of a high-quality AlGaN/AlN template layer. An output power of 1.8 mW at a pulsed current of 400 mA was achieved for a single 300 µm×300 µm diode. This device reached a high peak external quantum efficiency of 0.24% at 40 mA. An array of four diodes produced 6.5 mW at 880 mA of pulsed current. [reprint (PDF)]
2.	Very high performance LWIR and VLWIR type-II InAs/GaSb superlattice photodiodes with M-structure barrier B.M. Nguyen, D. Hoffman, P.Y. Delaunay, E.K. Huang and M. Razeghi SPIE Proceedings, Vol. 7082, San Diego, CA 2008, p. 708205-- September 3, 2008 ...[Visit Journal] LWIR and VLWIR type-II InAs/GaSb superlattice photodetectors have for long time suffered from a high dark current level and a low dynamic resistance which hampers the its emergence to the infrared detection and imaging industry. However, with the use of M-structure superlattice, a new Type-II binary InAs/GaSb/AlSb superlattice design, as an effective blocking barrier, the dark current in type-II superlattice diode has been significantly reduced. We have obtained comparable differential resistance product to the MCT technology at the cut-off wavelength of 10 and 14μm. Also, this new design is compatible with the optical optimization scheme, leading to high quantum efficiency, high special detectivity devices for photon detectors and focal plane arrays. [reprint (PDF)]
2.	Sharp/Tuneable UVC Selectivity and Extreme Solar Blindness in Nominally Undoped Ga2O3 MSM Photodetectors Grown by Pulsed Laser Deposition D. J. Rogers, A. Courtois, F. H. Teherani, V. E. Sandana, P. Bove, X. Arrateig, L. Damé, P. Maso, M. Meftah, W. El Huni, Y. Sama, H. Bouhnane, S. Gautier, A. Ougazzaden, M. Razeghi Proc. SPIE 11687, Oxide-based Materials and Devices XII, 116872D (24 March 2021); doi: 10.1117/12.2596194 ...[Visit Journal] Ga2O3 layers were grown on c-sapphire substrates by pulsed laser deposition. Optical transmission spectra were coherent with a bandgap engineering from 4.9 to 6.2 eV controlled via the growth conditions. X-ray diffraction revealed that the films were mainly β-Ga2O3 (monoclinic) with strong (-201) orientation. Metal-Semiconductor-Metal photodetectors based on gold/nickel Inter- Digitated-Transducer structures were fabricated by single-step negative photolithography. 240 nm peak response sensors gave over 2 orders-of-magnitude of separation between dark and light signal with state-of-the-art solar and visible rejection ratios ((I240 : I290) of > 3 x 105 and (I240 : I400) of > 2 x 106) and dark signals of <50 pA (at a bias of -5V). Spectral responsivities showed an exceptionally narrow linewidth (16.5 nm) and peak values exhibited a slightly superlinear increase with applied bias up to a value of 6.5 A/W (i.e. a quantum efficiency of > 3000%) at 20V bias. [reprint (PDF)]
2.	Review of high power frequency comb sources based on InP From MIR to THZ at CQD Manijeh Razeghi, Quanyong Lu, Donghai Wu, Steven Slivken Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States-- September 14, 2018 ...[Visit Journal] We present the recent development of high performance compact frequency comb sources based on mid-infrared quantum cascade lasers. Significant performance improvements of our frequency combs with respect to the continuous wave power output, spectral bandwidth, and beatnote linewidth are achieved by systematic optimization of the device's active region, group velocity dispersion, and waveguide design. To date, we have demonstrated the most efficient, high power frequency comb operation from a free-running room temperature continuous wave (RT CW) dispersion engineered QCL at λ~5-9 μm. In terms of bandwidth, the comb covered a broad spectral range of 120 cm⁻¹ with a radio-frequency intermode beatnote spectral linewidth of 40 Hz and a total power output of 880 mW at 8 μm and 1 W at ~5.0 μm. The developing characteristics show the potential for fast detection of various gas molecules. Furthermore, THz comb sources based on difference frequency generation in a mid-IR QCL combs could be potentially developed. [reprint (PDF)]
2.	High peak power 16 m InP-related quantum cascade laser A. Szerlinga,∗, S. Slivkenb, M. RazeghibaInstytut Opto-Electronics Review 25, pp. 205–208-- July 22, 2017 ...[Visit Journal] tIn this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with themaximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T₀) 272 K. Two types of the lasers were fabricatedand characterized: the lasers with a SiO₂ layer left untouched in the area of the metal-free window ontop of the ridge, and the lasers with the SiO₂layer removed from the metal-free window area. Dual-wavelength operation was obtained, at ∼15.6 μm (641 cm⁻¹) and at ∼16.6 μm (602 cm⁻¹) for laserswith SiO₂-removed, while within the emission spectrum of the lasers with SiO₂-left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO₂ layer showed ∼15% lower threshold current than these ones with the SiO₂ layer. The optical powers for lasers without SiO₂ layer were almost twice higher than for the lasers with the SiO₂ layer on the top of the ridge. [reprint (PDF)]
2.	Recent Advances in Room Temperature, High-Power Terahertz Quantum Cascade Laser Sources Based on Difference-Frequency Generation Quanyong Lu and Manijeh Razeghi Photonics, 3, 42-- July 7, 2016 ...[Visit Journal] We present the current status of high-performance, compact, THz sources based on intracavity nonlinear frequency generation in mid-infrared quantum cascade lasers. Significant performance improvements of our THz sources in the power and wall plug efficiency are achieved by systematic optimizing the device’s active region, waveguide, and chip bonding strategy. High THz power up to 1.9 mW and 0.014 mW for pulsed mode and continuous wave operations at room temperature are demonstrated, respectively. Even higher power and efficiency are envisioned based on enhancements in outcoupling efficiency and mid-IR performance. Our compact THz device with high power and wide tuning range is highly suitable for imaging, sensing, spectroscopy, medical diagnosis, and many other applications. [reprint (PDF)]
2.	High Performance Solar-Blind Ultraviolet Focal Plane Arrays Based on AlGaN Erdem Cicek, Ryan McClintock, Abbas Haddadi, William A. Gaviria Rojas, and Manijeh Razeghi IEEE Journal of Quantum Electronics, Vol. 50, Issue 8, p 591-595-- August 1, 2014 ...[Visit Journal] We report on solar-blind ultraviolet, AlxGa1-x N- based,p-i-n,focal plane array (FPA) with 92% operability. At the peak detection wavelength of 278 nm, 320×256-FP A-pixel showed unbiased peak external quantum efficiency (EQE) and responsivity of 49% and 109 mA/W, respectively, increasing to 66% under 5 volts of reverse bias. Electrical measurements yielded a low-dark current density: <7×10^-9A/cm², at FPA operating voltage of 2 volts of reverse bias. [reprint (PDF)]
2.	The effect of doping the M-barrier in very long-wave type-II InAs/GaSb heterodiodes D. Hoffman, B.M. Nguyen, E.K. Huang, P.Y. Delaunay, M. Razeghi, M.Z. Tidrow and J. Pellegrino Applied Physics Letters, Vol. 93, No. 3, p. 031107-1-- July 21, 2008 ...[Visit Journal] A variation on the standard homo-diode Type-II superlattice with an M-barrier between the pi-region and the n-region is shown to suppress the dark currents. By determining the optimal doping level of the M-superlattice, dark current densities of 4.95 mA·cm^-2 and quantum efficiencies in excess of 20% have been demonstrated at the moderate reverse bias of 50 mV; allowing for near background-limited performance with a Johnson-noise detectivity of 3.11×10¹⁰ Jones at 77 K for a 14.58 µm cutoff wavelength for large area diodes without passivation. This is comparable to values for the state-of-the-art HgCdTe photodiodes. [reprint (PDF)]
2.	High performance mid-wavelength quantum dot infrared photodetectors for focal plane arrays M. Razeghi, H. Lim, S. Tsao, M. Taguchi, W. Zhang and A.A. Quivy SPIE Conference, San Diego, CA, Vol. 6297, pp. 62970C-- August 13, 2006 ...[Visit Journal] Quantum dot infrared photodetectors (QDIPs) have recently emerged as promising candidates for detection in the middle wavelength infrared (MWIR) and long wavelength infrared (LWIR) ranges. Here, we report our recent results for mid-wavelength QDIPs grown by low-pressure metalorganic chemical vapor deposition. Three monolayer of In_0.68Ga_0.32As self-assembled via the Stranski-Krastanov growth mode and formed lens-shaped InGaAs quantum dots with a density around 3×10₁₀ cm^-2. The peak responsivity at 77 K was measured to be 3.4 A/W at a bias of -1.9 V with 4.7 µm peak detection wavelength. Focal plane arrays (FPAs) based on these devices have been developed. The preliminary result of FPA imaging is presented. [reprint (PDF)]
2.	Very high quality p-type Al_xGa_1-xN/GaN superlattice A. Yasan and M. Razeghi special ISDRS issue of Solid State Electronics Journal, 47-- January 1, 2003 ...[Visit Journal] Very high quality p-type Al_xGa_1−xN/GaN superlattice has been achieved through optimization of Mg flow and period of superlattice. Theoretical model was used to optimize the structure of superlattice by choosing suitable Al compositions and superlattice periods. The experiments show that for x=0.26, the resistivity is as low as 0.19 Ω cm and hole concentration is as high as 4.2×10¹⁸ cm⁻³, the highest values ever reported for p-type AlGaN/GaN superlattices. Hall effect measurement and admittance spectroscopy on the samples confirm the high quality of the superlattices. The activation energy calculated for p-type GaN and p-type A_0.1Ga_0.9N/GaN superlattice is estimated to be not, vert, similar 125 and 3 meV respectively. [reprint (PDF)]
2.	High Power 3-12 μm Infrared Lasers: Recent Improvements and Future Trends M. Razeghi, S. Slivken, A. Tahraoui, A. Matlis, and Y.S. Park Physica E: Low-Dimensional Systems and Nanostructures 11 (2-3)-- October 1, 2001 ...[Visit Journal] In this paper, we discuss the progress of quantum cascade lasers (QCLs) grown by gas-source molecular beam epitaxy. Room temperature QCL operation has been reported for lasers emitting between 5-11 μm, with 9-11 μm lasers operating up to 425 K. Laser technology for the 3-5 μm range takes advantage of a strain-balanced active layer design. We also demonstrate record room temperature peak output powers at 9 and 11 μm (2.5 and 1 W, respectively) as well as record low 80K threshold current densities (250 A/cm²) for some laser designs. Preliminary distributed feedback (DFB) results are also presented and exhibit single mode operation for 9 μm lasers at room temperature. [reprint (PDF)]
2.	Growth and Characterization of Type-II Non-Equilibrium Photovoltaic Detectors for Long Wavelength Infrared Range H. Mohseni, J. Wojkowski, A. Tahraoui, M. Razeghi, G. Brown and W. Mitche SPIE Conference, San Jose, CA, -- January 26, 2000 ...[Visit Journal] Growth and characterization of type-II detectors for mid-IR wavelength range is presented. The device has a p-i-n structure is designed to operate in the non-equilibrium mode with low tunneling current. The active layer is a short period InAs/GaSb superlattice. Wider bandgap p-type AlSb and n-type InAs layers are used to facilitate the extraction of both electronics and holes from the active layer for the first time. The performance of these devices were compared to the performance of devices grown at the same condition, but without the AlSb barrier layers. The processed devices with the AlSb barrier show a peak responsivity of about 1.2 A/W with Johnson noise limited detectivity of 1.1 X 10¹¹ cm·Hz^½/W at 8 μm at 80 K at zero bias. The details of the modeling, growth, and characterizations will be presented. [reprint (PDF)]
2.	Low pressure metalorganic chemical vapor deposition of high quality AlN and GaN thin films on sapphire and silicon substrates P. Kung, X. Zhang, E. Bigan, and M. Razeghi Optoelectronic Integrated Circuit Materials, Physics and Devices, SPIE Conference, San Jose, CA; Proceedings, Vol. 2397-- February 6, 1995 ...[Visit Journal] High quality AlN and GaN epilayers have been grown on basal plane sapphire by low pressure metalorganic chemical vapor deposition. The X-ray rocking curve linewidth of the AlN and GaN films were about 100 and 30 arcsecs respectively. Sharp absorption edges were determined at 6.1 and 3.4 eV respectively. Successful donor-bound excitonic luminescence emissions were detected for GaN films grown on sapphire and silicon. Two additional lines at 3.37 and 3.31 eV were observed on GaN on sapphire and assumed to be impurity-related. Doping of GaN layers was achieved with magnesium. Mg-related photoluminescence emissions were successfully detected on as-grown samples, without any post-growth treatment. [reprint (PDF)]
2.	Optical Investigations of GaAs-GaInP Quantum Wells and Superlattices Grown by Metalorganic Chemical Vapor Deposition Omnes F., and Razeghi M. Applied Physics Letters 59 (9), p. 1034-- May 28, 1991 ...[Visit Journal] Recent experimental results on the photoluminescence and photoluminescence excitation of GaAs‐Ga_0.51In_0.49P lattice‐matched quantum wells and superlattices are discussed. The full width at half maximum of a 10‐period GaAs‐GaInP superlattice with Lz=90 Å and LB=100 Å is 4 meV at 4 K. The photoluminescence excitation exhibits very sharp peaks attributed to the electron to light‐hole and electron to heavy‐hole transitions. The GaInP‐GaAs interface suffers from memory effect of In, rather than P or As elements. [reprint (PDF)]
2.	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)]
2.	High Detectivity InAs Quantum-Dot Infrared Photodetectors Grown on InP by Metalorganic Chemical Vapor Deposition W. Zhang, H. Lim, M. Taguchi, S. Tsao, B. Movaghar, and M. Razeghi Applied Physics Letters, 86 (19)-- May 9, 2005 ...[Visit Journal] We report a high-detectivity InAs quantum-dot infrared photodetector. The InAs quantum dots were grown by self-assembly on InP substrates via low-pressure metal–organic chemical–vapor deposition. Highly uniform quantum dots with a density of 4×10¹⁰ cm² were grown on a GaAs/InP matrix. Photoresponse was observed at temperatures up to 160 K with a peak of 6.4 µm and cutoff of 6.6 µm. Very low dark currents and noise currents were obtained by inserting Al_0.48In_0.52As current blocking layers. The background-limited performance temperature was 100 K. A detectivity of 1.0×10¹⁰ cm·Hz^½/W was obtained at 77 K with a bias of –1.1 V. [reprint (PDF)]

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