Center for Quantum Devices - Most Downloaded Journal Articles

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11.	A Review of III-Nitride Research at the Center for Quantum Devices M. Razeghi and R. McClintock Journal of Crystal Growth, Vol. 311, No. 10-- May 1, 2009 ...[Visit Journal] In this paper, we review the history of the Center for Quantum Devices’ (CQD) III-nitride research covering the past 15 years. We review early work developing III-nitride material growth. We then present a review of laser and light-emitting diode (LED) results covering everything from blue lasers to deep UV LEDs emitting at 250 nm. This is followed by a discussion of our UV photodetector research from early photoconductors all the way to current state of the art Geiger-mode UV single photon detectors. [reprint (PDF)]
11.	Electroluminescence at 375 nm from a Zn0/GaN:Mg/c-Al₂O₃ heterojunction light emitting diodes D.J. Rogers, F.Hosseini Teherani, A. Yasan, K. Minder, P. Kung, and M. Razeghi Applied Physics Letters, 88 (14)-- April 13, 2006 ...[Visit Journal] n-ZnO/p-GaN:Mg heterojunction light emitting diode (LED) mesas were fabricated on c-Al₂O₃ substrates using pulsed laser deposition for the ZnO and metal organic chemical vapor deposition for the GaN:Mg. Room temperature (RT) photoluminescence (PL) showed an intense main peak at 375 nm and a negligibly low green emission indicative of a near band edge excitonic emission from a ZnO layer with low dislocation/defect density. The LEDs showed I-V characteristics confirming a rectifying diode behavior and a RT electroluminescence (EL) peaked at about 375 nm. [reprint (PDF)]
11.	Radiometric characterization of long-wavelength infrared type II strained layer superlattice focal plane array under low-photon irradiance conditions J. Hubbs, V. Nathan, M. Tidrow, and M. Razeghi Optical Engineering, Vol. 51, No. 6, p. 064002-1-- June 15, 2012 ...[Visit Journal] We present the results of the radiometric characterization of an “M” structure long wavelength infrared Type-II strained layer superlattice(SLS) infrared focal plane array (IRFPA) developed by Northwestern University (NWU). The performance of the M-structure SLS IRFPA was radiometrically characterized as a function of photon irradiance, integration time, operating temperature, and detector bias. Its performance is described using standard figures of merit: responsivity, noise, and noise equivalent irradiance. Assuming background limited performance operation at higher irradiances, the detector quantum efficiency for the SLS detector array is approximately 57%. The detector dark density at 80 K is 142 μA∕cm², which represents a factor of seven reduction from previously measured devices. [reprint (PDF)]
11.	Persistent photoconductivity in Ga0.49In0.51P/GaAs heterojunctions S. Ben Amor; L. Dmowski; J. C. Portal; N. J. Pulsford; R. J. Nicholas; J. Singleton; M. Razeghi J. Appl. Phys. 65, 2756–2760 (1989-- November 18, 1988 ...[Visit Journal] We have studied the persistent photoconductivity (PPC) effect in Ga0.49 Ino. sl P IGaAs heterostructures. Through time- and temperature-dependent Hall effect, we observe very small relaxation rates and the PPC remains observable at room temperature. Optical experiments show an optical energy threshold of 1.15 e V and an infrared quenching of the ppc. Thermal cycling of the samples strongly affects the PPC and the quenching temperature. The center responsible for the observed PPC, therefore, appears related to defects, Most of our observations are qualitatively understood in a large lattice relaxation DX-like center approach. However, the origin of the high quenching temperature remains to be explained. [reprint (PDF)]
11.	High quantum efficiency mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodiodes grown by metal-organic chemical vapor deposition Donghai Wu , Quentin Durlin, Arash Dehzangi , Yiyun Zhang , and Manijeh Razeghi Appl. Phys. Lett. 114, 011104-- January 8, 2019 ...[Visit Journal] We report the growth and characterization of mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodiodes on GaSb substrates grown by metal-organic chemical vapor deposition. At 150 K, the 50% cut-off wavelength is 5.0 um, the dark current density is 3.3x10⁻⁴ A/cm² under −20mV bias, and the peak responsivity is 1.76A/W corresponding to a quantum efficiency of 55% without anti-reflection coating. A specific detectivity of 1.2x10¹¹cmHz^1/2/W is achieved at 4.0 um under −20mV bias at 150 K. [reprint (PDF)]
11.	GaN nanostructured p-i-n photodiodes J.L. Pau, C. Bayram, P. Giedraitis, R. McClintock, and M. Razeghi Applied Physics Letters, Vol. 93, No. 22, p. 221104-1-- December 1, 2008 ...[Visit Journal] We report the fabrication of nanostructured p-i-n photodiodes based on GaN. Each device comprises arrays of ~200 nm diameter and 520 nm tall nanopillars on a 1 µm period, fabricated by e-beam lithography. Strong rectifying behavior was obtained with an average reverse current per nanopillar of 5 fA at −5 V. In contrast to conventional GaN diodes, nanostructured devices reproducibly show ideality factors lower than 2. Enhanced tunneling through sidewall surface states is proposed as the responsible mechanism for this behavior. Under backillumination, the quantum efficiency in nanostructured devices is partly limited by the collection efficiency of holes into the nanopillars. [reprint (PDF)]
11.	Electrically pumped photonic crystal distributed feedback quantum cascade lasers Y. Bai, P. Sung, S.R. Darvish, W. Zhang, A. Evans, S. Slivken, and M. Razeghi SPIE Conference, January 20-25, 2008, San Jose, CA Proceedings – Quantum Sensing and Nanophotonic Devices V, Vol. 6900, p. 69000A-1-8.-- February 1, 2008 ...[Visit Journal] We demonstrate electrically pumped, room temperature, single mode operation of photonic crystal distributed feedback (PCDFB) quantum cascade lasers emitting at ~ 4.75 µm. Ridge waveguides of 50 µm and 100 µm width were fabricated with both PCDFB and Fabry-Perot feedback mechanisms. The Fabry-Perot device has a broad emitting spectrum and a broad far-field character. The PCDFB devices have primarily a single spectral mode and a diffraction limited far field characteristic with a full angular width at half-maximum of 4.8 degrees and 2.4 degrees for the 50 µm and 100 µm ridge widths, respectively. [reprint (PDF)]
11.	Ultraviolet avalanche photodiodes Ryan McClintock ; Manijeh Razeghi Proc. SPIE 9555, Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications, 95550B -- August 28, 2015 ...[Visit Journal] The III-Nitride material system is rapidly maturing; having proved itself as a material for LEDs and laser, and now finding use in the area of UV photodetectors. However, many UV applications are still dominated by the use of photomultiplier tubes (PMT). PMTs are capable of obtaining very high sensitivity using internal electron multiplication gain (typically ~106). It is highly desirable to develop a compact semiconductor-based photodetector capable of realizing this level of sensitivity. In principle, this can be obtained in III-Nitrides by taking advantage of avalanche multiplication under high electric fields – typically 2.7 MV/cm, which with proper design can correspond to an external reverse bias of less than 100 volts. In this talk, we review the current state-of-the-art in III-Nitride solar- and visible-blind APDs, and present our latest results on GaN APDs grown 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 were compared. The spectral response and Geiger-mode photon counting performance of UV APDs are studied under low photon fluxes, with single photon detection capabilities as much as 30% being demonstrated in smaller devices. Geiger-mode operation conditions are optimized for enhanced SPDE. [reprint (PDF)]
11.	Room temperature continuous wave, monolithic tunable THz sources based on highly efficient mid-infrared quantum cascade lasers Quanyong Lu, Donghai Wu, Saumya Sengupta, Steven Slivken, Manijeh Razeghi Nature Scientific Reports 6, Article number: 23595-- March 24, 2016 ...[Visit Journal] A compact, high power, room temperature continuous wave terahertz source emitting in a wide frequency range (ν ~ 1–5 THz) is of great importance to terahertz system development for applications in spectroscopy, communication, sensing, and imaging. Here, we present a strong-coupled strain-balanced quantum cascade laser design for efficient THz generation based on intracavity difference frequency generation. Room temperature continuous wave emission at 3.41 THz with a side-mode suppression ratio of 30 dB and output power up to 14 μW is achieved with a wall-plug efficiency about one order of magnitude higher than previous demonstrations. With this highly efficient design, continuous wave, single mode THz emissions with a wide frequency tuning range of 2.06–4.35 THz and an output power up to 4.2 μW are demonstrated at room temperature from two monolithic three-section sampled grating distributed feedback-distributed Bragg reflector lasers. [reprint (PDF)]
11.	EPR Study of Gd around the Ferroelastic Transition Point of Pb3 (PO4)2 M. RAZEGHI and B. HOULIER M. RAZEGHI et al., phys. stat. sol. (b) 89, K135 (1978) -- October 1, 1978 ...[Visit Journal][reprint (PDF)]
11.	High-power continuous-wave operation of distributed-feedback quantum-cascade lasers at λ ~ 7.8 µm S.R. Darvish, W. Zhang, A. Evans, J.S. Yu, S. Slivken, and M. Razeghi Applied Physics Letters, 89 (25)-- December 18, 2006 ...[Visit Journal] The authors present high-power continuous-wave (cw) operation of distributed-feedback quantum-cascade lasers. Continuous-wave output powers of 56 mW at 25 °C and 15 mW at 40 °C are obtained. Single-mode emission near 7.8 μm with a side-mode suppression ratio of >=30 dB and a tuning range of 2.83 cm⁻¹ was obtained between 15 and 40 °C. The device exhibits no beam steering with a full width at half maximum of 27.4° at 25 °C in cw mode. [reprint (PDF)]
11.	Suppressing Spectral Crosstalk in Dual-Band LongWavelength Infrared Photodetectors With Monolithically Integrated Air-Gapped Distributed Bragg Reﬂectors Yiyun Zhang, Abbas Haddadi, Arash Dehzangi , Romain Chevallier, Manijeh Razeghi IEEE Journal of Quantum Electronics Volume: 55, Issue:1-- November 22, 2018 ...[Visit Journal] Antimonide-based type-II superlattices (T2SLs) have made possible the development of high-performance infrared cameras for use in a wide variety of thermal imaging applications, many of which could beneﬁt from dual-band imaging. The performance of this material system has not reached its limits. One of the key issues in dual-band infrared photodetection is spectral crosstalk. In this paper, air-gapped distributed Bragg reﬂectors (DBRs) have been monolithically integrated between the two channels in long-/very long-wavelength dualband InAs/InAs_1−xSb_x/AlAs_1−xSb_x-based T2SLs photodetectors to suppress the spectral crosstalk. This air-gapped DBR has achieved a signiﬁcant spectral suppression in the 4.5–7.5-µm photonic stopband while transmitting the optical wavelengths beyond 7.5 µm, which is conﬁrmed by theoretical calculations, numerical simulation, and experimental results. [reprint (PDF)]
11.	Geiger-mode operation of back-illuminated GaN avalanche photodiodes J. L. Pau, R. McClintock, K. Minder, C. Bayram, P. Kung, M. Razeghi, E. Muñoz, and D. Silversmith Applied Physics Letters, Vol. 91, No. 04, p. 041104 -1-- July 23, 2007 ...[Visit Journal] We report the Geiger-mode operation of back-illuminated GaN avalanche photodiodes fabricated on transparent AlN templates specifically for back illumination in order to enhance hole-initiated multiplication. The spectral response in Geiger-mode operation was analyzed under low photon fluxes. Single photon detection capabilities were demonstrated in devices with areas ranging from 225 to 14,063 µm². Single photon detection efficiency of 20% and dark count rate < 10 kHz were achieved in the smallest devices. [reprint (PDF)]
11.	GaInN/GaN Multi-Quantum Well Laser Diodes Grown by Low-Pressure Metalorganic Chemical Vapor Deposition P. Kung, A. Saxler, D. Walker, A. Rybaltowski, X. Zhang, J. Diaz, and M. Razeghi MRS Internet Journal of Nitride Semiconductor Research 3 (1)-- January 1, 1998 ...[Visit Journal] We report the growth, fabrication and characterization of GaInN/GaN multi-quantum well lasers grown on (00·1) sapphire substrates by low pressure metalorganic chemical vapor deposition. The threshold current density of a 1800 µm long cavity length laser was 1.4 kA/cm² with a threshold voltage of 25 V. These lasers exhibited series resistances of 13 and 14 Ω at 300 and 79 K, respectively. [reprint (PDF)]
11.	Top-emission ultraviolet light-emitting diodes with peak emission at 280 nm A. Yasan, R. McClintock, K. Mayes, S.R. Darvish, P. Kung, and M. Razeghi Virtual Journal of Nanoscale Science & Technology, 5-- August 5, 2002 ...[Visit Journal][reprint (PDF)]
11.	High quality LEO growth and characterization of GaN films on Al₂O₃ and Si substrates M. Razeghi, P. Kung, D. Walker, M. Hamilton, and J. Diaz SPIE International Conference on Solid State Crystals, Zakopane, Poland; Proceedings 3725-- October 12, 1998 ...[Visit Journal] We report the lateral epitaxial overgrowth (LEO) of GaN films on (00.1) Al₂O₃ and (111) Si substrates by metalorganic chemical vapor deposition. The LEO on Si substrates was possible after achieving quasi monocrystalline GaN template films on (111) Si substrates. X-ray diffraction, photoluminescence, scanning electron microscopy and atomic force microscopy were used to assess the quality of the LEO films. Lateral growth rates more than 5 times as high as vertical growth rates were achieved for both LEO growths of GaN on sapphire and silicon substrates. [reprint (PDF)]
11.	GaInAsP/InP 1.35 μm Double Heterostructure Laser Grown on Silicon Substrate by Metalorganic Chemical Vapor Deposition K. Mobarhan, C. Jelen, E. Kolev, and M. Razeghi Journal of Applied Physics 74 (1)-- July 1, 1993 ...[Visit Journal] A 1.35 μm GaInAsP/InP double heterostructure laser has been grown on a Si substrate using low‐pressure metalorganic chemical vapor deposition. This was done without the use of a superlattice layer or a very thick InP buffer layer, which are used to prevent the dislocations from spreading into the active layer. Pulsed operation with output power of over 200 mW per facet was achieved at room temperature for broad area lasers with 20 μm width and 170 μm cavity length. The threshold current density of a 350 μm cavity length device was 9.8 kA/cm². The characteristic temperature was 66 K. [reprint (PDF)]
11.	Extended electrical tuning of quantum cascade lasers with digital concatenated gratings S. Slivken, N. Bandyopadhyay, Y. Bai, Q. Y. Lu, and M. Razeghi Appl. Phys. Lett. 103, 231110 (2013)-- December 6, 2013 ...[Visit Journal] In this report, the sampled grating distributed feedback laser architecture is modified with digital concatenated gratings to partially compensate for the wavelength dependence of optical gain in a standard high efficiency quantum cascade laser core. This allows equalization of laser threshold over a wide wavelength range and demonstration of wide electrical tuning. With only two control currents, a full tuning range of 500 nm (236 cm⁻¹) has been demonstrated. Emission is single mode, with a side mode suppression of >20 dB. [reprint (PDF)]
11.	Reliability of Aluminum-Free 808 nm High-Power Laser Diodes with Uncoated Mirrors I. Eliashevich, J. Diaz, H. Yi, L. Wang, and M. Razeghi Applied Physics Letters 66 (23)-- June 5, 1995 ...[Visit Journal] The reliability of uncoated InGaAsP/GaAs high‐power diode lasers emitting at 808 nm wavelength has been studied. 47 W of quasicontinuous wave output power (pulse width 200 μs, frequency 20 Hz) have been obtained from a 1 cm wide laser bar. A single‐stripe diode without mirror coating has been life tested at 40 °C for emitting power of 800 mW continuous wave (cw) and showed no noticeable degradation and no change of the lasing wavelength after 6000 h of operation. [reprint (PDF)]
11.	MOCVD Growth of ZnO Nanostructures Using Au Droplets as Catalysts V.E. Sandana, D.J. Rogers, F.H. Teherani, R. McClintock, M. Razeghi, H.J. Drouhin, M.C. Clochard, V. Sallett, G. Garry and F. Fayoud SPIE Conference, January 20-25, 2008, San Jose, CA Proceedings – Zinc Oxide Materials and Devices III, Vol. 6895, p. 68950Z-1-6.-- February 1, 2008 ...[Visit Journal] ZnO nanostructures were synthesised by Metal Organic Chemical Vapor Deposition growth on Si (100) and c-Al₂O₃ substrates coated with a 5nm thick layer of Au. The Au coated substrates were annealed in air prior to deposition of ZnO so as to promote formation of Au nanodroplets. The development of the nanodroplets was studied as a function of annealing duration and temperature. Under optimised conditions, a relatively homogeneous distribution of regular Au nanodroplets was obtained. Using the Au nanodroplets as a catalyst, MOCVD growth of ZnO nanostructures was studied. Scanning electron microscopy revealed nanostructures with various forms including commonly observed structures such as nanorods, nanoneedles and nanotubes. Some novel nanostructures were also observed, however, which resembled twist pastries and bevelled-multifaceted table legs. [reprint (PDF)]
10.	Thermal conductivity tensors of the cladding and active layers of antimonide infrared lasers and detectors Chuanle Zhou, I. Vurgaftman, C. L. Canedy, C. S. Kim, M. Kim, W. W. Bewley, C. D. Merritt, J. Abell, J. R. Meyer, A. Hoang, A. Haddadi, M. Razeghi, and M. Grayson Optical Materials Express. 2013;3(10):1632-1640.-- October 1, 2013 ...[Visit Journal] The in-plane and cross-plane thermal conductivities of the cladding layers and active quantum wells of interband cascade lasers and type-II superlattice infrared detector are measured by the 2-wire 3ω method. The layers investigated include InAs/AlSb superlattice cladding layers, InAs/GaInSb/InAs/AlSb W-active quantum wells, an InAs/GaSb superlattice absorber, an InAs/GaSb/AlSb M-structure, and an AlAsSb digital alloy. The in-plane thermal conductivity of the InAs/AlSb superlattice is 4-5 times higher than the cross-plane value. The isotropic thermal conductivity of the AlAsSb digital alloy matches a theoretical expectation, but it is one order of magnitude lower than the only previously-reported experimental value. [reprint (PDF)]
10.	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."
10.	Interface roughness scattering in thin, undoped GaInP/GaAs quantum wells W. C. Mitchel, G.J. Brown, I. Lo, S. Elhamri, M. Aboujja, K. Ravindran, R.S. Newrock, M. Razeghi, and X. He Applied Physics Letters 65 (12)-- September 19, 1994 ...[Visit Journal] Electronic transport properties of very thin undoped GaInP/GaAs quantum wells have been measured by temperature dependent low field Hall effect and by Shubnikov–de Haas effect. Strong Shubnikov–de Haas oscillations were observed after increasing the electron concentration via the persistent photocurrent effect. Low temperature mobilities of up to 70 ,000 cm²/V· s at carrier concentrations of 6.5×10¹¹ cm⁻² were observed in a 20 Å quantum well. The results are compared with the theory of interface roughness scattering which indicates extremely smooth interfaces; however, discrepancies between experiment and theory are observed. [reprint (PDF)]
10.	Concentration gradient at an InP/GaAs interface determined by Auger analysis on a chemical bevel J. Cazaux; P. Etienne; M. Razeghi J. Cazaux, P. Etienne, M. Razeghi; Concentration gradient at an InP/GaAs interface determined by Auger analysis on a chemical bevel. J. Appl. Phys. 15 May 1986; 59 (10): 3598–3601-- June 15, 1986 ...[Visit Journal] Experimental results of Auger profiles obtained on a chemical bevel of an InP/GaAs structure are reported. A theoretical procedure is established to convert the intensity profile into concentration profiles. It is applied to evaluate the concentration distribution of each species–Ga, In, As, P–independently of each others with a precision of ±5%. It is verified that the composition of the interface is GaxIn1−xAsyP1−y (0≤x, y≤1). Owing to differences between the atomic diffusions of III‐ and V‐type elements, the transition region can be subdivided into three regions having the following compositions: (i) GaAsyP1−y with 0.87≤y≤1; (ii) GaxIn1−xAsyP1−y with 0≤y≤0.87 and 0.24≤x<1; (iii) PGaxIn1−x with x<0.24. The width of each region is also indicated. [reprint (PDF)]
10.	Mid‑wavelength infrared avalanche photodetector with AlAsSb/GaSb superlattice Jiakai Li, Arash Dehzangi, Gail Brown, Manijeh Razeghi Scientifc Reports \| (2021) 11:7104 \| https://doi.org/10.1038/s41598-021-86566-8 ...[Visit Journal] In this work, a mid-wavelength infrared separate absorption and multiplication avalanche photodiode (SAM-APD) with 100% cut-of wavelength of ~ 5.0 µm at 200 K grown by molecular beam epitaxy was demonstrated. The InAsSb-based SAM-APD device was designed to have electron dominated avalanche mechanism via the band structure engineered multi-quantum well structure based on AlAsSb/GaSb H-structure superlattice and InAsSb material in the multiplication region. The device exhibits a maximum multiplication gain of 29 at 200 K under -14.7 bias voltage. The maximum multiplication gain value for the MWIR SAM-APD increases from 29 at 200 K to 121 at 150 K. The electron and hole impact ionization coefficients were derived and the large difference between their value was observed. The carrier ionization ratio for the MWIR SAM-APD device was calculated to be ~ 0.097 at 200 K. [reprint (PDF)]

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