Center for Quantum Devices - Most Downloaded Journal Articles

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13.	Intersubband hole absorption in GaAs-GaInP Quantum Wells grown by Gas Source Molecular Beam Epitaxy J. Hoff, C. Jelen, S. Slivken, E. Michel, O. Duchemin, E. Bigan, and M. Razeghi with G. Brown and S.M. Hegde (Wright Laboratory) Applied Physics Letters 65 (9)-- August 29, 1994 ...[Visit Journal] P-doped GaAs‐GaInP quantum wells have been grown on GaAs substrate by gas source molecular beam epitaxy. Structural quality has been evidenced by x-ray diffraction. A narrow low-temperature photoluminescence full width at half‐maximum has been measured. Strong hole intersubband absorption has been observed at 9 μm, and its dependence on light polarization has been investigated. [reprint (PDF)]
13.	Responsivity and Noise Performance of InGaAs/InP Quantum Well Infrared Photodetectors C. Jelen, S. Slivken, T. David, G. Brown, and M. Razeghi SPIE Conference, San Jose, CA, -- January 28, 1998 ...[Visit Journal] Dark current nose measurements were carried out between 10 and 104 Hz at T = 80K on two InGaAs/InP quantum well IR photo detectors (QWIPs) designed for 8 μm IR detection. Using the measured noise data, we have calculated the thermal generation rate, bias-dependent gain, electron trapping probability, and electron diffusion length. The calculated thermal generation rate is similar to AlGaAs/GaAs QWIPs with similar peak wavelengths, but the gain is 50X larger, indicating improved transport and carrier lifetime are obtained in the binary InP barriers. As a result, a large responsivity of 7.5 A/W at 5V bias and detectivity of 5 X 10¹¹ cm·Hz^½/W at 1.2 V bias were measured for the InGaAs/InP QWIPs at T = 80K. [reprint (PDF)]
13.	High Detectivity GaInAs/InP Quantum Well Infrared Photodetectors Grown on Si Substrates J. Jiang, C. Jelen, M. Razeghi and G.J. Brown IEEE Photonics Technology Letters 14 (3)-- March 1, 2002 ...[Visit Journal] In this letter, we report an improvement in the growth and the device performance of GaInAs-InP quantum well infrared photodetectors grown on Si substrates. Material growth techniques, like low-temperature nucleation layers and thick buffer layers were used to grow InP on Si. An in situ thermal cycle annealing technique was used to reduce the threading dislocation density in the InP-on-Si. Detector dark current was reduced 2 orders of magnitude by this method. Record high detectivity of 2.3 × 10⁹ cm·Hz^½·W^-1 was obtained for QWIP-on-Si detectors in the 7-9 μm range at 77 K [reprint (PDF)]
13.	Harmonic injection locking of high-power mid-infrared quantum cascade lasers Feihu Wang, Steven Slivken, and Manijeh Razeghi OSA Photonics Research •https://doi.org/10.1364/PRJ.423573 ...[Visit Journal] High-power, high-speed quantum cascade lasers (QCLs) with stable emission in the mid-infrared regime are of great importance for applications in metrology, telecommunication, and fundamental tests of physics. Owing to the inter-sub-band transition, the unique ultrafast gain recovery time of the QCL with picosecond dynamics is expected to overcome the modulation limit of classical semiconductor lasers and bring a revolution for the next generation of ultrahigh-speed optical communication. Therefore, harmonic injection locking, offering the possibility to fast modulate and greatly stabilize the laser emission beyond the rate limited by cavity length, is inherently adapted to QCLs. In this work, we demonstrate for the first time the harmonic injection locking of a mid-infrared QCL with an output power over 1 watt in continuous-wave operation at 288 K. Compared with an unlocked laser, the inter-mode spacing fluctuation of an injection locked QCL can be considerably reduced by a factor above 1×10 E3, which permits the realization of an ultra-stable mid-infrared semiconductor laser with high phase coherence and frequency purity. Despite temperature change, this fluctuation can be still stabilized to hertz level by a microwave modulation up to ∼18 GHz. These results open up the prospect of the applications of mid-infrared QCL technology for frequency comb engineering, metrology and the next generation ultrahigh-speed telecommunication. It may also stimulate new schemes for exploring ultrafast mid-infrared pulse generation in QCLs. [reprint (PDF)]
13.	State-of-the-art Type II Antimonide-based superlattice photodiodes for infrared detection and imaging M. Razeghi, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, S. Abdollahi Pour, P. Manurkar, and S. Bogdanov SPIE Proceedings, Nanophotonics and Macrophotonics for Space Environments II, San Diego, CA, Vol. 7467, p. 74670T-1-- August 5, 2009 ...[Visit Journal] Type-II InAs/GaSb Superlattice (SL), a system of multi interacting quantum wells was first introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this low dimensional system has drawn a lot of attention for its attractive quantum mechanics properties and its grand potential for the emergence into the application world, especially in infrared detection. In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs and imaging applications which elevated the performances of Type-II InAs/GaSb superlattice photodetectors to a comparable level to the state-of-the-art Mercury Cadmium Telluride. We will present in this talk the current status of the state-of-the-art Type II superlattice photodetectors and focal plane arrays, and the future outlook for this material system. [reprint (PDF)]
13.	Ultraviolet Detector Materials and Devices Studied by Femtosecond Nonlinear Optical Techniques M. Wraback, H. Shen, P. Kung, M. Razeghi, J.C. Carrano, T. Li, and J.C. Campbell SPIE Conference, San Jose, CA, -- January 26, 2000 ...[Visit Journal] Femtosecond nonlinear optical techniques have been employed in the study of carrier dynamics and transport in UV detector materials. Visible femtosecond pulses derived from the signal beam of a 250 kHz regenerative amplifier-pumped optical parametric amplifier were frequency doubled to obtain pulses tunable from 250 nm to 375 nm. Time-resolved reflectivity experiments indicate that the room-temperature carrier lifetime in GaN grown by double lateral epitaxial overgrowth is about 3 times longer than that of GaN grown on sapphire without benefit of this technique. The electron velocity-field characteristics and saturation velocity in GaN have been obtained form time-resolved studies of electroabsorption in a GaN p-i-n diode. The peak steady- state velocity of 1.9x10⁷ cm/s in this device occurs at 225 kV/cm. Time-resolved transmission measurements have been used to monitor ultrafast carrier relaxation phenomena in a thin AlGaN layer with bandgap in the solar blind region of the spectrum. Excitation intensity and wavelength dependent studies of the photoinduced bleaching decays suggest that they are primarily governed by trapping in a high density of sub-bandgap defect levels. [reprint (PDF)]
13.	Broadband, Tunable, and Monolithic Quantum Cascade Lasers M. Razeghi, Q. Y. Lu, N. Bandyopadhyay, W. Zhou, D. Heydari, Y. Bai, and S. Slivken. Semiconductor lasers; (140.3600) Lasers, tunable-- May 19, 2017 ...[Visit Journal] This article describes the state of research and recent developments related to broadband quantum cascade lasers. Monolithic tuning and system development is also discussed. [reprint (PDF)]
13.	8-13 μm InAsSb heterojunction photodiode operating at near room temperature J.D. Kim, S. Kim, D. Wu, J. Wojkowski, J. Xu, J. Piotrowski, E. Bigan, and M. Razeghi Applied Physics Letters 67 (18)-- October 30, 1995 ...[Visit Journal] p⁺-InSb/π-InAs_1−xSb_x/n⁺-InSb heterojunction photodiodes operating at near room temperature in the 8–13 μm region of infrared (IR) spectrum are reported. A room‐temperature photovoltaic response of up to 13 μm has been observed at 300 K with an x≊0.85 sample. The voltage responsivity‐area product of 3×10⁻⁵ V· cm²/W has been obtained at 300 K for the λ=10.6 μm optimized device. This was close to the theoretical limit set by the Auger mechanism, with a detectivity at room temperature of ≊1.5×10⁸ cm ·Hz^½/W. [reprint (PDF)]
13.	Room temperature terahertz quantum cascade laser sources with 215 μW output power through epilayer-down mounting Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai, and M. Razeghi Appl. Phys. Lett. 103, 011101 (2013)-- July 1, 2013 ...[Visit Journal] We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215 μW are obtained, respectively. [reprint (PDF)]
13.	GaN-based nanostructured photodetectors J.L. Pau, C. Bayram, P. Giedraitis, R. McClintock, and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7222-14-- January 26, 2009 ...[Visit Journal] The use of nanostructures in semiconductor technology leads to the observation of new phenomena in device physics. Further quantum and non-quantum effects arise from the reduction of device dimension to a nanometric scale. In nanopillars, quantum confinement regime is only revealed when the lateral dimensions are lower than 50 nm. For larger mesoscopic systems, quantum effects are not observable but surface states play a key role and make the properties of nanostructured devices depart from those found in conventional devices. In this work, we present the fabrication of GaN nanostructured metal-semiconductor-metal (MSM) and p-i-n photodiodes (PIN PDs) by e-beam lithography, as well as the investigation of their photoelectrical properties at room temperature. The nanopillar height and diameter are about 520 nm and 200 nm, respectively. MSMs present dark currents densities of 0.4 A/cm² at ±100 V. A strong increase of the optical response with bias is observed, resulting in responsivities higher than 1 A/W. The relationship between this gain mechanism and surface states is discussed. PIN PDs yield peak responsivities (R_peak) of 35 mA/W at -4 V and show an abnormal increase of the response (R_peak > 100 A/W) under forward biases. [reprint (PDF)]
13.	Study on the effects of minority carrier leakage in InAsSb/InPAsSb double heterostructure B. Lane, D. Wu, H.J. Yi, J. Diaz, A. Rybaltowski, S. Kim, M. Erdtmann, H. Jeon and M. Razeghi Applied Physics Letters 70 (11)-- April 17, 1997 ...[Visit Journal] InAs_xSb_1−x/InP_1−x−yAs_xSb_y double heterostructures have been grown on InAs substrates by metal-organic chemical vapor deposition. The minority carrier leakage to the cladding layers was studied with photoluminescence measurements on the InAsSb/InPAsSb double heterostructures. A carrier leakage model is used to extract parameters related to the leakage current (diffusion-coefficient and length) from experimental results. Using the obtained parameters, the temperature dependence of the threshold current density of InAsSb/InPAsSb double heterostructure lasers is predicted and compared with experimental results. [reprint (PDF)]
13.	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)]
13.	Solar-blind photodetectors based on Ga₂O₃ and III-nitrides Ryan McClintock; Alexandre Jaud; Lakshay Gautam; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128803-- January 31, 2020 ...[Visit Journal] Recently, there has been a surge of interest in the wide bandgap semiconductors for solar blind photo detectors (SBPD). This work presents our recent progress in the growth/doping of AlGaN and Ga₂O₃ thin films for solar blind detection applications. Both of these thin films grown are grown by metal organic chemical vapor deposition (MOCVD) in the same Aixtron MOCVD system. Solar-blind metal-semiconductor-metal photodetectors were fabricated with Ga₂O₃. Spectral responsivity studies of the MSM photodetectors revealed a peak at 261 nm and a maximum EQE of 41.7% for a −2.5 V bias. We have also demonstrated AlGaN based solar-blind avalanche photodiodes with a gain in excess of 57,000 at ~100 volts of reverse bias. This gain can be attributed to avalanche multiplication of the photogenerated carriers within the device. Both of these devices show the potential of wide bandgap semiconductors for solar blind photo detectors. [reprint (PDF)]
13.	cw operation of 1.57‐μm GaxIn1−xAsyP1−yInP distributed feedback lasers grown by low‐pressure metalorganic chemical vapor deposition M. Razeghi; R. Blondeau; K. Kazmierski; M. Krakowski; B. de Cremoux; J. P. Duchemin; J. C. Bouley Appl. Phys. Lett. 45, 784–786 (1984)-- October 1, 1984 ...[Visit Journal] Continuous wave operation of 1. 57-Jim distributed feedback lasers fabricated on material grown by two-step low-pressure metalorganic chemical vapor deposition growth process is reported for the first time. Room-temperature continuous wave threshold currents as low as 60 rnA have been measured for devices with cavity length of 300 Jim and stripe width of 5 Jim. Single longitudinal mode operation at fixed mode was obtained under the continuous wave condition, in the temperature range 9-90 °C, with the wavelength shift of 0.9 A/C. A stop band of25 A in which no resonance mode emission existed, was observed in the output spectrum of the distributed feedback laser. [reprint (PDF)]
13.	Recent advances in IR semiconductor laser diodes and future trends M. Razeghi; Y. Bai; N. Bandyopadhyay; B. Gokden; Q.Y. Lu; S. Slivken Photonics Society Summer Topical Meeting Series, IEEE [6000041], pp. 55-56 (2011)-- July 18, 2011 ...[Visit Journal] The wall plug efficiency of the mid-infrared quantum cascade laser in room temperature continuous wave (cw) operation is brought to 21%, with a maximum output power of 5.1 W. Using a surface grating distributed feedback (DFB) approach, we demonstrated 2.4 W single mode output in room temperature cw operation. With a photonic crystal distributed feedback (PCDFB) design, we achieved single mode spectrum and close to diffraction limited far field with a room temperature high peak power of 34 W. [reprint (PDF)]
13.	First GaInAsP‐InP double‐heterostructure laser emitting at 1.27 μm on a silicon substrate M. Razeghi; M. Defour; F. Omnes; Ph. Maurel; J. Chazelas; F. Brillouet Appl. Phys. Lett. 53, 725–727 (1988)-- June 21, 1988 ...[Visit Journal] We report the first successful room-temperature GalnAsP-InP double-heterostructure laser emitting at 1.27 pm, grown by low-pressure metalorganic chemical vapor deposition on a Si substrate. A pulsed threshold current density of 10 kAlcm2 at room temperature with an external quantum efficiency of 10% per facet and an output power of20 mW (for an oxidedefined stripe geometry with 12 pm stripe width and 250 pm cavity length) has been measured. The first aging test in pulse operation shows an increase of threshold current of only 7% for a cumulative time of 80 s at room temperature. [reprint (PDF)]
13.	Photoluminescence linewidth narrowing in Yb-doped GaN and InGaN thin films K. Dasari, J. Wang, W.M. Jadwisienczak, V. Dierolf, M. Razeghi, R. Palai Journal of Luminescence Volume 209, May 2019, Pages 237-243-- January 14, 2019 ...[Visit Journal] We report on photoluminescence (PL) properties of GaN, GaN:Yb, InGaN, and InGaN:Yb thin films grown on (0001) sapphire substrates by plasma assisted molecular beam epitaxy (MBE). X-ray diffraction pattern of the films confirms c-axis oriented growth. The concentration of Yb and In was obtained by X-ray photoelectron spectroscopy (XPS) and was found to be 5 (+/- 0.5) at.% and 30 (+/- 1.5) at.%, respectively. The GaN:Yb and InGaN:Yb thin films show a significant linewidth narrowing in PL spectra compared to GaN and InGaN thin films. This could be attributed to the reduction of the defect related non-radiative recombination paths and suppression of the structural defects and dislocations because of the in situ rare earth (Yb)-doping during the growth. The temperature dependent photoluminescence of GaN:Yb thin film follows the Varshni model, whereas InGaN:Yb film shows a complex S-shaped like behavior, which can be explained by the localization effect using the Band-Tail model. [reprint (PDF)]
13.	High-performance InP-based midinfrared quantum cascade lasers at Northwestern University M. Razeghi, Y. Bai, S. Slivken, and S.R. Darvish SPIE Optical Engineering, Vol. 49, No. 11, November 2010, p. 111103-1-- November 15, 2010 ...[Visit Journal] We present recent performance highlights of midinfrared quantum cascade lasers (QCLs) based on an InP material system. At a representative wavelength around 4.7 µm, a number of breakthroughs have been achieved with concentrated effort. These breakthroughs include watt-level continuous wave operation at room temperature, greater than 50% peak wall plug efficiency at low temperatures, 100-W-level pulsed mode operation at room temperature, and 10-W-level pulsed mode operation of photonic crystal distributed feedback quantum cascade lasers at room temperature. Since the QCL technology is wavelength adaptive in nature, these demonstrations promise significant room for improvement across a wide range of mid-IR wavelengths. [reprint (PDF)]
13.	UV photodetectors based on Al_xGa_1-xN grown by MOCVD A. Saxler, D. Walker, X. Zhang, P. Kung, J. Xu, and M. Razeghi SPIE Photonics West '96 Photodetectors: Materials and Devices; Proceedings 2685-- January 27, 1996 ...[Visit Journal] Metalorganic chemical vapor deposition was used to deposit Al_xGa_1-xN active layers with varying aluminum compositions on basal plane sapphire substrate. Al_xGa_1-xN (x < 0.5) ultraviolet photodetectors have been fabricated and characterized with cut-off wavelengths as short as 260 nm. Carrier lifetimes on the order of 10 milliseconds were estimated from frequency dependent measurements of the responsivity. [reprint (PDF)]
13.	Recent progress of widely tunable, CW THz sources based QCLs at room temperature Manijeh Razeghi Terahertz Science and Technology, Vol.10, No.4, pp. 87-151-- December 7, 2017 ...[Visit Journal] The THz spectral region is of significant interest to the scientific community, but is one of the hardest regions to access with conventional technology. A wide range of compelling new applications are initiating a new revolution in THz technology, especially with regard to the development of compact and versatile devices for THz emission and detection. In this article, recent advances with regard to III-V semiconductor optoelectronics are explored with emphasis on how these advances will lead to the next generation of THz component technology [reprint (PDF)]
13.	Recent advances in high performance antimonide-based superlattice FPAs E.K. Huang, B.M. Nguyen, S.R. Darvish, S. Abdollahi Pour, G. Chen, A. Haddadi, and M.A. Hoang SPIE Proceedings, Infrared technology and Applications XXXVII, Orlando, FL, Vol. 8012, p. 80120T-1-- April 25, 2011 ...[Visit Journal] Infrared detection technologies entering the third generation demand performances for higher detectivity, higher operating temperature, higher resolution and multi-color detection, all accomplished with better yield and lower manufacturing/operating costs. Type-II antimonide based superlattices (T2SL) are making firm steps toward the new era of focal plane array imaging as witnessed in the unique advantages and significant progress achieved in recent years. In this talk, we will present the four research themes towards third generation imagers based on T2SL at the Center for Quantum Devices. High performance LWIR megapixel focal plane arrays (FPAs) are demonstrated at 80K with an NEDT of 23.6 mK using f/2 optics, an integration time of 0.13 ms and a 300 K background. MWIR and LWIR FPAs on non-native GaAs substrates are demonstrated as a proof of concept for the cost reduction and mass production of this technology. In the MWIR regime, progress has been made to elevate the operating temperature of the device, in order to avoid the burden of liquid nitrogen cooling. We have demonstrated a quantum efficiency above 50%, and a specific detectivity of 1.05x10¹² cm·Hz^1/2/W at 150 K for 4.2 μm cut-off single element devices. Progress on LWIR/LWIR dual color FPAs as well as novel approaches for FPA fabrication will also be discussed. [reprint (PDF)]
13.	III-Nitride avalanche photodiodes R. McClintock, J.L. Pau, C. Bayram, B. Fain, P. Giedratis, M. Razeghi and M. Ulmer SPIE Proceedings, San Jose, CA Volume 7222-0U-- January 26, 2009 ...[Visit Journal] Research into avalanche photodiodes (APDs) is motivated by the need for high sensitivity ultraviolet (UV) detectors in numerous civilian and military applications. By designing photodetectors to utilize low-noise impact ionization based gain, GaN APDs operating in Geiger mode can deliver gains exceeding 1×10⁷. Thus with careful design, it becomes possible to count photons at the single photon level. In this paper we review the current state of the art in III-Nitride visible-blind APDs, and present our latest results regarding linear and Geiger mode III-Nitride based APDs. This includes novel device designs such as separate absorption and multiplication APDs (SAM-APDs). We also discuss control of the material quality and the critical issue of p-type doping - demonstrating a novel delta-doping technique for improved material quality and enhanced electric field confinement. The spectral response and Geiger-mode photon counting performance of these devices are then analyzed under low photon fluxes, with single photon detection capabilities being demonstrated. Other major technical issues associated with the realization of high-quality visible-blind Geiger mode APDs are also discussed in detail and future prospects for improving upon the performance of these devices are outlined. [reprint (PDF)]
12.	High power photonic crystal distributed feedback quantum cascade lasers emitting at 4.5 micron B. Gokden, S. Slivken and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 760806-1-- January 22, 2010 ...[Visit Journal] Quantum cascade lasers possess very small linewidth enhancement factor, which makes them very prominent candidates for realization of high power, nearly diffraction limited and single mode photonic crystal distributed feedback broad area lasers in the mid-infrared frequencies. In this paper, we present room temperature operation of a two dimensional photonic crystal distributed feedback quantum cascade laser emitting at 4.5 µm. peak power up to ~0.9 W per facet is obtained from a 2 mm long laser with 100 µm cavity width at room temperature. The observed spectrum is single mode with a very narrow linewidth. Far-field profile has nearly diffraction limited single lobe with full width at half maximum of 3.5 degree normal to the facet. The mode selection and power output relationships are experimentally established with respect to different cavity lengths for photonic crystal distributed feedback quantum cascade lasers. [reprint (PDF)]
12.	Fabrication of GaN Nanotubular Material using MOCVD with an Aluminium Oxide Membrane W.G. Jung, S.H. Jung, P. Kung, and M. Razeghi Nanotechnology 17-- January 1, 2006 ...[Visit Journal] GaN nanotubular material is fabricated with an aluminium oxide membrane in MOCVD. SEM, XRD, TEM and PL are employed to characterize the fabricated GaN nanotubular material. An aluminium oxide membrane with ordered nanoholes is used as a template. Gallium nitride is deposited at the inner wall of the nanoholes in the aluminium oxide template, and the nanotubular material with high aspect ratio is synthesized using the precursors of TMG and ammonia gas. Optimal synthesis conditions in MOCVD are obtained successfully for the gallium nitride nanotubular material in this research. The diameter of the GaN nanotube fabricated is approximately 200–250 nm and the wall thickness is about 40–50 nm. [reprint (PDF)]
12.	Hole-initiated multiplication in back-illuminated GaN avalanche photodiodes R. McClintock, J.L. Pau, K. Minder, C. Bayram, P. Kung and M. Razeghi Applied Physics Letters, Vol. 90 No. 14, p. 141112-1-- April 2, 2007 ...[Visit Journal] Avalanche p-i-n photodiodes were fabricated on AlN templates for back illumination. Structures with different intrinsic layer thicknesses were tested. A critical electric field of 2.73 MV/cm was estimated from the variation of the breakdown voltage with thickness. From the device response under back and front illumination and the consequent selective injection of holes and electrons in the junction, ionization coefficients were obtained for GaN. The hole ionization coefficient was found to be higher than the electron ionization coefficient as predicted by theory. Excess multiplication noise factors were also calculated for back and front illumination, and indicated a higher noise contribution for electron injection. [reprint (PDF)]

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