Center for Quantum Devices - Most Downloaded Journal Articles

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12.	Strain-Induced Metastable Phase Stabilization in Ga₂O₃ Thin Films Yaobin Xu, Ji-hyeon Park, Zhenpeng Yao, Christopher Wolverton, Manijeh Razeghi, Jinsong Wu, and Vinayak P. Dravid Acs Appl Mater Inter 11 (5), 5536 (2019)-- January 10, 2019 ...[Visit Journal] It is well known that metastable and transient structures in bulk can be stabilized in thin films via epitaxial strain (heteroepitaxy) and appropriate growth conditions that are often far from equilibrium. However, the mechanism of heteroepitaxy, particularly how the nominally unstable or metastable phase gets stabilized, remains largely unclear. This is especially intriguing for thin film Ga₂O₃, where multiple crystal phases may exist under varied growth conditions with spatial and dimensional constraints. Herein, the development and distribution of epitaxial strain at the Ga₂O₃/Al₂O₃ film-substrate interfaces is revealed down to the atomic resolution along different orientations, with an aberration-corrected scanning transmission electron microscope (STEM). Just a few layers of metastable α-Ga₂O₃ structure were found to accommodate the misfit strain in direct contact with the substrate. Following an epitaxial α-Ga₂O₃ structure of about couple unit cells, several layers (4~5) of transient phase appear as the intermediate structure to release the misfit strain. Subsequent to this transient crystal phase, the nominally unstable κ-Ga₂O₃ phase is stabilized as the major thin film phase form. We show that the epitaxial strain is gracefully accommodated by rearrangement of the oxygen polyhedra. When the structure is under large compressive strain, Ga3+ ions occupy only the oxygen octahedral sites to form a dense structure. With gradual release of the compressive strain, more and more Ga3+ ions occupy the oxygen tetrahedral sites, leading to volumetric expansion and the phase transformation. The structure of the transition phase is identified by high resolution electron microscopy (HREM) observation, complemented by the density functional theory (DFT) calculations. This study provides insights from the atomic scale and their implications for the design of functional thin film materials using epitaxial engineering. [reprint (PDF)]
12.	MOCVD grown β-Ga₂O₃ metal-oxide-semiconductor field effect transistors on sapphire Ji-Hyeon Park , Ryan McClintock, Alexandre Jaud, Arash Dehzangi , Manijeh Razeghi Applied Physics Express 12, 095503-- August 28, 2019 ...[Visit Journal] We fabricated β-Ga₂O₃:Si metal-oxide field-effect transistors (MOSFETs) on c-plane sapphire substrates which typically showed maximum drain current of 100 mA·mm⁻¹. β-Ga₂O₃:Si thin films were realized on c-plane sapphire substrates through a combination of metalorganic chemical vapor deposition and post-annealing. The MOSFET device presented excellent on/off drain current ratio of ∼10¹¹ with very low gate leakage current, sharp pinch off behavior, and a breakdown voltage of 400 V at VG = −40 V. The growth and fabrication of β-Ga₂O₃:Si MOSFETs on c-plane sapphire is valuable to its demonstration of the great potential for future high-power electronic devices. [reprint (PDF)]
12.	Investigation of the Heteroepitaxial Interfaces in the GaInP/GaAs Superlattices by High Resolution X-Ray Diffraction and Dynamical Solutions Xiaoguang He and Manijeh Razeghi Journal of Applied Physics 73 (7)-- April 1, 1993 ...[Visit Journal] Two GaAs/GaInP superlattices grown on GaAs substrates by low‐pressure metalorganic chemical vapor deposition have been studied using high resolution x‐ray diffraction measurements and simulations by solving Tagaki–Taupin equations. The strained layers at both interfaces of the GaAs well are identified from the simulations of the measured diffraction patterns. The purging of indium at the interface of GaInP/GaAs accounts for the strained layer at the GaInP/GaAs interface while the pressure difference in the gas lines, which results in the different traveling time to the sample surface, is attributed to the indium‐poor strained layer at the GaAs/GaInP interface. It is shown that high‐resolution x‐ray diffraction measurements combined with a dynamical simulation, are sensitive tools to study the heteroepitaxial interfaces on an atomic layer scale. In addition, the influence of a miscut of the substrate on the measurement is discussed in the article. It is shown that even though the miscut is small, the diffraction geometry is already an asymmetric one. More than 10% error in the superlattice period for a 2° miscut substrate can result when the miscut substrate is considered a symmetric geometry. [reprint (PDF)]
12.	Quantum-Cascade Lasers Operating in Continuous-Wave Mode Above 90°C at λ ~5.25 µm A. Evans, J. Nguyen, S. Slivken, J.S. Yu, S.R. Darvish, and M. Razeghi Applied Physics Letters 88 (5)-- January 30, 2006 ...[Visit Journal] We report on the design and fabrication of λ~5.25 μm quantum-cascade lasers (QCLs) for very high temperature continuous-wave (CW) operation. CW operation is reported up to a maximum temperature of 90 °C (363 K). CW output power is reported in excess of 500 mW near room temperature with a low threshold current density. A finite element thermal model is used to investigate the G_th and maximum CW operating temperature of the QCLs. [reprint (PDF)]
12.	High‐quality GaAs/Ga0.49In0.51P superlattices grown on GaAs and silicon substrates by low‐pressure metalorganic chemical vapor deposition Available M. Razeghi; Ph. Maurel; F. Omnes; M. Defour; C. Boothroyd; W. M. Stobbs; M. Kelly J. Appl. Phys. 63, 4511–4514 (1988) -- May 1, 1988 ...[Visit Journal] We report the successful growth of Ga0.49 Iuo.5 ! P-GaAs superlattices on GaAs and Si substrates by low-pressure metalorganic chemical vapor deposition. The high quality of the structure grown on GaAs and silicon substrates has been evidenced by transmission electron microscopy photographs, that show very sharp interfaces between GaAs wells and Gao.49InO.51 P barriers, with perfect control of thicknesses and compositions. Classical Hall measurements performed on the sample further demonstrated the presence of a twodimensional electron ga.<; with a mobility at T = 4 K , fL (4 K) = 50000 cm2 1V Is, and a carrier concentration n _ (4 K) = 2,9 X 1011 em -2. GaAs/Gao.49 InO. 51 P superlattices have been used, as well as buffer layer in order to grow GaAs on silicon substrates. Mirrorlike single-crystal GaAs has thus been obtained. A GaInP IGaAs heterostructure with electron HaH mobility as high as 6000 cm2 /V Is at 300 K and 80000 cm2 /V Is at 4 K has been grown, which is the highest mobility that has yet been reported for these materials, [reprint (PDF)]
12.	Stranski-Krastanov growth of InGaN quantum dots emitting in green spectra C. Bayram and M. Razeghi Applied Physics A: Materials Science and Processing, Vol. 96, No. 2, p. 403-408-- August 1, 2009 ...[Visit Journal] Self-assembled InGaN quantum dots (QDs) were grown on GaN templates by metalorganic chemical vapor deposition. 2D–3D growth mode transition through Stranski–Krastanov mode was observed via atomic force microscopy. The critical thickness for In_0.67Ga_0.33N QDs was determined to be four monolayers. The effects of growth temperature, deposition thickness, and V/III ratio on QD formation were examined. The capping of InGaN QDs with GaN was analyzed. Optimized InGaN quantum dots emitted in green spectra at room temperature. [reprint (PDF)]
12.	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)]
12.	Growth of In_1-xTl_xSb, a New Infrared Material, by Low-Pressure Metalorganic Chemical Vapor Deposition Y.H. Choi, R. Sudharsanan, C, Besikci, and M. Razeghi Applied Physics Letters 63 (3)-- July 19, 1993 ...[Visit Journal] We report the growth of In_1-xTl_xSb, a new III-V alloy for long-wavelength infrared detector applications, by low-pressure metalorganic chemical vapor deposition. In_1-xTl_xSb with good surface morphology was obtained on both GaAs and InSb substrates at a growth temperature of 455 °C. X-ray diffraction measurements showed resolved peaks of In_1-xTl_xSb and InSb films. Infrared absorption spectrum of In_1-xTl_xSb showed a shift toward lower energies compared to InSb spectrum. Hall mobility data on In_1-xTl_xSb/InSb/GaAs structure showed enhanced mobility at low temperatures compared to InSb/GaAs structure. [reprint (PDF)]
12.	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)]
12.	InAs quantum dot infrared photodetectors on InP by MOCVD W. Zhang, H. Lim, M. Taguchi, A. Quivy and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61270M -- January 23, 2006 ...[Visit Journal] We report our recent results of InAs quantum dots grown on InP substrate by low-pressure metalorganic chemical vapor deposition (MOCVD) for the application of quantum dot infrared photodetector (QDIP). We have previously demonstrated the first InP-based QDIP with a peak detection wavelength at 6.4 µm and a detectivity of 10¹⁰ cm·Hz^½/W at 77K. Here we show our recent work toward shifting the detection wavelength to the 3-5 µm middlewavelength infrared (MWIR) range. The dependence of the quantum dot on the growth conditions is studied by atomic force microscopy, photoluminescence and Fourier transform infrared spectroscopy. Possible ways to increase the quantum efficiency of QDIPs are discussed. [reprint (PDF)]
12.	AlGaN-based deep-ultraviolet 320 x 256 focal plane array E. Cicek, Z. Vashaei, E.K. Huang, R. McClintock and M. Razeghi OSA Optics Letters, Vol. 37, No. 5, p. 896-898-- March 1, 2012 ...[Visit Journal] We report the synthesis, fabrication, and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, Al_xGa_1−xN–based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al_xGa_1−xN layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. 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. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows 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)]
12.	Broadband monolithically-tunable quantum cascade lasers Wenjia Zhou, Ryan McClintock, Donghai Wu, Steven Slivken, Manijeh Razeghi Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV, 105400A-- January 26, 2018 ...[Visit Journal] Mid-infrared lasers, emitting in the spectral region of 3-12 μm that contain strong characteristic vibrational transitions of many important molecules, are highly desirable for spectroscopy sensing applications. High efficiency quantum cascade lasers have been demonstrated with up to watt-level output power in the mid-infrared region. However, the wide wavelength tuning, which is critical for spectroscopy applications, is still largely relying on incorporating external gratings, which have stability issues. Here, we demonstrate the development a monolithic, widely tunable quantum cascade laser source emitting between 6.1 and 9.2 μm through an on-chip integration of a sampled grating distributed feedback tunable laser array with a beam combiner. A compact tunable laser system was built to drive the individual lasers within the array and coordinate the driving of the laser array to produce desired wavelength. A broadband spectral measurement (520cm^-1) of methane shows excellent agreement with Fourier transform infrared spectrometer measurement. Further optimizations have led to high performance monolithic tunable QCLs with up to 65 mW output while delivering fundamental mode outputs. [reprint (PDF)]
12.	Electron spin resonance in the two-dimensional electron gas of a GaAs-Gax In1-xP heterostructure M DoberstS, J P Vierent, M RazeghiS, M DefourS and F Ornnes Semicond. Sci. Technol. 4 (1989) 687-690-- June 12, 1989 The microwave-induced change of the magnetoresistivity of GaAs-GalnP heterostructures reveals resonant structure which is attributed to electron spin resonance of the two-dimensional conduction electrons. The spin splitting of the two lowest Landau levels has been investigated as a function of the magnetic field. From these studies we obtain the dependence of the g-factor on the magnetic field and the Landau level. These results are compared with those obtained in GaAs-AIGaAs heterostructures. [reprint (PDF)]
12.	The quantum Hall effect in modulation doped In0.53Ga0.47As-InP heterojunctions Y. Guldner, J.P. Hirtz, J.P. Vieren, P. Voisin, M. Voos, M. Razeghi Journal de Physique Lettres, 43 (16), pp.613-616 (1982)-- November 30, 1999 ...[Visit Journal] We report the first observation of the quantum Hall effect in modulation doped In0.53Ga0.47As-InP heterojunctions at 4.2 and 1.5 K. The results are then compared to data obtained in a GaAs-AlxGa1-xAs heterojunction having similar electronic characteristics. [reprint (PDF)]
11.	High Quantum Efficiency Solar-Blind Photodetectors R. McClintock, A. Yasan, K. Mayes, D. Shiell, S. Darvish, P. Kung and M. Razeghi SPIE Conference, Jose, CA, Vol. 5359, pp. 434-- January 25, 2004 ...[Visit Journal] We report AlGaN-based back-illuminated solar-blind p-i-n photodetectors with a record peak responsivity of 150 mA/W at 280 nm, corresponding to a high external quantum efficiency of 68%, increasing to 74% under 5 volts reverse bias. Through optimization of the p-AlGaN layer, we were able to remove the out-of-band negative photoresponse originating from the Schottky-like p-type metal contact, and hence significantly improve the degree of solar-blindness [reprint (PDF)]
11.	Quntum Cascade Laser Breakthrough for Advanced Remote Detection Manijeh Razeghi, Wenjia Zhou, Donghai Wu, Ryan McClintock, and Steven Slivken Photonics Spectra, November issue-- November 1, 2016 ...[Visit Journal] The atoms in a molecule can bend, stretch and rotate with respect to one another, and these excitations are largely optically active. Most molecules, from simple to moderately complex, have a characteristic absorption spectrum in the 3- to 14-µrn wavelength range that can be uniquely identified and quantified in real time. Infrared spectroscopy has been used to study these absorption features and develop different molecular "fingerprints." [reprint (PDF)]
11.	Surface leakage current reduction in long wavelength infrared type-II InAs/GaSb superlattice photodiodes S. Bogdanov, B.M. Nguyen, A.M. Hoang, and M. Razeghi Applied Physics Letters, Vol. 98, No. 18, p. 183501-1-- May 2, 2011 ...[Visit Journal] Dielectric passivation of long wavelength infrared Type-II InAs/GaSb superlattice photodetectors with different active region doping profiles has been studied. SiO₂ passivation was shown to be efficient as long as it was not put in direct contact with the highly doped superlattice. A hybrid graded doping profile combined with the shallow etch technique reduced the surface leakage current in SiO₂ passivated devices by up to two orders of magnitude compared to the usual design. As a result, at 77 K the SiO(2) passivated devices with 10.5 μm cutoff wavelength exhibit an R₀A of 120 Ω·cm², R_maxA of 6000 Ω·cm², and a dark current level of 3.5×10⁻⁵ A·cm⁻² at −50 mV bias. [reprint (PDF)]
11.	Deep Fe and intrinsic defect levels in Ga0.47In0.53As/InP K.‐H. Goetz; D. Bimberg; K.‐A. Brauchle; H. Jürgensen; J. Selders; M. Razeghi; E. Kuphal K.‐H. Goetz, D. Bimberg, K.‐A. Brauchle, H. Jürgensen, J. Selders, M. Razeghi, E. Kuphal; Deep Fe and intrinsic defect levels in Ga0.47In0.53As/InP. Appl. Phys. Lett. 1 February 1985; 46-- February 1, 1985 ...[Visit Journal] Two deep traps in Ga0.47In0.53As/InP:Fe at a depth of 110 meV and 150 meV, respectively, are observed for the first time using low‐temperature photoluminescence and deep level transient spectroscopy. The dependence of luminescence intensity on the growth process itself (liquid phase epitaxy, vapor phase epitaxy, and metalorganic chemical vapor deposition) and its parameters (growth temperature, layer thickness) and the substrate doping is reported and leads to the unambigous identification of the 150‐meV acceptorlike trap as being caused by Fe impurities. Fe diffuses from the substrate to the epitaxial layer during the growth process. This outdiffusion is less pronounced for layers grown at lower temperature. The level at 110 meV which is also observed in layers grown on InP:S substrate is tentatively assigned to an intrinsic defect of Ga0.47In0.53As. [reprint (PDF)]
11.	High-speed free-space optical communications based on quantum cascade lasers and type-II superlattice detectors Stephen M. Johnson; Emily Dial; M. Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128814-- January 31, 2020 ...[Visit Journal] Free-space optical communications (FSOC) is a promising avenue for point-to-point, high-bandwidth, and high-security communication links. It has the potential to solve the “last mile” problem modern communication systems face, allowing for high-speed communication links without the expensive and expansive infrastructure required by fiber optic and wireless technologies 1 . Although commercial FSOC systems currently exist, due to their operation in the near infrared and short infrared ranges, they are necessarily limited by atmospheric absorption and scattering losses 2 . Mid-infrared (MWIR) wavelengths are desirable for free space communications systems because they have lower atmospheric scattering losses compared to near-infrared communication links. This leads to increased range and link uptimes. Since this portion of the EM spectrum is unlicensed, link establishment can be implemented quickly. Quantum cascade lasers (QCL) are ideal FSOC transmitters because their emission wavelength is adjustable to MWIR 3 . Compared to the typical VCSEL and laser diodes used in commercial NIR and SWIR FSOC systems, however, they require increased threshold and modulation currents 4 . Receivers based on type-II superlattice (T2SL) detectors are desired in FSOC for their low dark current, high temperature operation, and band gap tunable to MWIR 5. In this paper, we demonstrate the implementation of a high-speed FSOC system using a QCL and a T2SL detector. [reprint (PDF)]
11.	Substrate removal for high quantum efficiency back side illuminated type-II InAs/GaSb photodetectors P.Y. Delaunay, B.M. Nguyen, D. Hoffman and M. Razeghi Applied Physics Letters, Vol. 91, No. 23, p. 231106-- December 3, 2007 ...[Visit Journal] A substrate removal technique using an InAsSb etch stop layer improves by a factor of 2 the quantum efficiency of back side illuminated type-II InAs/GaSb superlattice photodetectors. After etching of the GaSb substrate with a CrO₃ based solution, the quantum efficiency of the diodes presents Fabry-Pérot oscillations averaging at 56%. Due to the confinement of the infrared light inside the devices, the quantum efficiency for certain devices reaches 75% at 8.5 µm. The implementation of this new technique to a focal plane array resulted in a decrease of the integration time from 0.23 to 0.08 ms. [reprint (PDF)]
11.	Recent advances in III-Nitride materials, characterization and device applications M. Razeghi, X. Zhang, P. Kung, A. Saxler, D. Walker, K.Y. Lim, and K.S. Kim SPIE Conference: Solid State Crystals in Optoelectronics and Semiconductor Technology; Proceedings 3179-- October 7, 1996 ...[Visit Journal] High-quality AlN, GaN, AlGaN have been grown on sapphire substrate by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The x-ray rocking curve of AlN and GaN were 100 arcsecs and 30 arcsecs respectively with Pendelloesung oscillations, which are the best reported to date. GaN with high crystallinity simultaneously exhibited high optical and electrical quality. Photoluminescence linewidth of GaN at 77K was as low as 17 meV, which is the best reported to date. Si-doped GaN had a mobility higher than 300 cm²/V·s. GaN has been also successfully grown on LiGaO₂ substrate with LP-MOCVD for the first time. AlGaN for the entire composition range has been grown. These layers exhibited the lowest x-ray FWHM reported to date. The excellent optical quality of these layers have been characterized by room temperature UV transmission and photoluminescence. N-type doping of AlGaN with Si has ben achieved up to 60 percent Al with mobility as high as 78 cm²/V·s. Al_xGa_1-xN/Al_yGa_1-yN superlattice with atomically sharp interface have been demonstrated. Optically-pumped stimulated emission in GaN:Ge and GaN:Si has been observed with threshold optical power density as low as 0.4 MW/cm². AlGaN photoconductors with cut-off wavelengths from 200 nm to 365 nm have been achieved for the first time. GaN p-n junction photovoltaic detector with very selective photoresponse have been demonstrated and theoretically modeled. Ti/AlN/Si metal-insulator- semiconductor capacitor with high capacitance-voltage performances at both low and high frequencies and low interface trap level density have been demonstrated for the first time in this material system. [reprint (PDF)]
11.	Passivation of Type-II InAs/GaSb Superlattice Photodiodes A. Gin, Y. Wei, J. Bae, A. Hood, J. Nah, and M. Razeghi International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego, CA; Thin Solid Films 447-448-- January 30, 2004 ...[Visit Journal] Recently, excellent infrared detectors have been demonstrated using Type-II InAs/GaSb superlattice materials sensitive at wavelengths from 3 μm to greater than 32 μm. These results indicate that Type-II superlattice devices may challenge the preponderance of HgCdTe and other state-of-the-art infrared material systems. As such, surface passivation is becoming an increasingly important issue as progress is made towards the commercialization of Type-II devices and focal plane array applications. This work focuses on initial attempts at surface passivation of Type-II InAs/GaSb superlattice photodiodes using PECVD-grown thin layers of SiO₂. Our results indicate that silicon dioxide coatings deposited at various temperatures improve photodetector resistivity by several times. Furthermore, reverse-bias dark current has been reduced significantly in passivated devices. [reprint (PDF)]
11.	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)]
11.	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)]
11.	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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