Center for Quantum Devices - Most Downloaded Journal Articles

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18.	High Quality Type-II InAs/GaSb Superlattices with Cutoff Wavelength ~3.7 µm Using Interface Engineering Y. Wei, J. Bae, A. Gin, A. Hood, M. Razeghi, G.J. Brown, and M. Tidrow Journal of Applied Physics, 94 (7)-- October 1, 2003 ...[Visit Journal] We report the most recent advance in the area of Type-II InAs/GaSb superlattices that have cutoff wavelength of ~3.7 µm. With Ga_xIn_1–x type interface engineering techniques, the mismatch between the superlattices and the GaSb (001) substrate has been reduced to <0.1%. There is no evidence of dislocations using the best examination tools of x-ray, atomic force microscopy, and transmission electron microscopy. The full width half maximum of the photoluminescence peak at 11 K was ~4.5 meV using an Ar+ ion laser (514 nm) at fluent power of 140 mW. The integrated photoluminescence intensity was linearly dependent on the fluent laser power from 2.2 to 140 mW at 11 K. The temperature-dependent photoluminescence measurement revealed a characteristic temperature of one T1 = 245 K at sample temperatures below 160 K with fluent power of 70 mW, and T1 = 203 K for sample temperatures above 180 K with fluent power of 70 and 420 mW. [reprint (PDF)]
18.	High-power, continuous-operation intersubband laser for wavelengths greater than 10 micron S. Slivken, A. Evans, W. Zhang and M. Razeghi Applied Physics Letters, Vol. 90, No. 15, p. 151115-1-- April 9, 2007 ...[Visit Journal] In this letter, high-power continuous-wave emission (>100 mW) and high temperature operation (358 K) at a wavelength of 10.6 µm is demonstrated using an individual diode laser. This wavelength is advantageous for many medium-power applications previously reserved for the carbon dioxide laser. Improved performance was accomplished using industry-standard InP-based materials and by careful attention to design, growth, and fabrication limitations specific to long-wave infrared semiconductor lasers. The main problem areas are explored with regard to laser performance, and general steps are outlined to minimize their impact. [reprint (PDF)]
18.	Demonstration of type-II superlattice MWIR minority carrier unipolar imager for high operation temperature application Guanxi Chen, Abbas Haddadi, Anh-Minh Hoang, Romain Chevallier, and Manijeh Razeghi Optics Letters Vol. 40, Iss. 1, pp. 29–32-- December 18, 2014 ...[Visit Journal] An InAs/GaSb type-II superlattice-based mid-wavelength infrared (MWIR) 320×256 unipolar focal plane array (FPA) using pMp architecture exhibited excellent infrared image from 81 to 150 K and ∼98% operability, which illustrated the possibility for high operation temperature application. At 150 K and −50 mV operation bias, the 27 μm pixels exhibited dark current density to be 1.2×10⁻⁵ A/cm², with 50% cutoff wavelength of 4.9 μm, quantum efficiency of 67% at peak responsivity (4.6 μm), and specific detectivity of 1.2×10¹² Jones. At 90 K and below, the 27 μm pixels exhibited system limited dark current density, which is below 1×10⁻⁹ A/cm², and specific detectivity of 1.5×10¹⁴ Jones. From 81 to 100 K, the FPA showed ∼11 mK NEDT by using F/2.3 optics and a 9.69 ms integration time. [reprint (PDF)]
18.	Background limited performance of long wavelength infrared focal plane arrays fabricated from M-structure InAs/GaSb superlattices P.Y. Delaunay, B.M. Nguyen, D. Hoffman, E.K. Huang, P. Manurkar, S. Bogdanov and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7222-0W-- January 26, 2009 ...[Visit Journal] Recent advances in the design and fabrication of Type-II InAs/GaSb superlattices allowed the realization of high performance long wavelength infrared focal plane arrays. The introduction of an Mstructure barrier between the n-type contact and the pi active region reduced the tunneling component of the dark current. The M-structure design improved the noise performance and the dynamic range of FPAs at low temperatures. At 81K, the NEDT of the focal plane array was 23 mK. The noise of the camera was dominated by the noise component due to the read out integrated circuit. At 8 µm, the median quantum efficiency of the detectors was 71%, mainly limited by the reflections on the backside of the array. [reprint (PDF)]
18.	Multi-band SWIR-MWIR-LWIR Type-II superlattice based infrared photodetector Manijeh Razeghi, Arash Dehzangi, Jiakai Li Results in Optics Volume 2, January 2021, 100054 https://doi.org/10.1016/j.rio.2021.100054 ...[Visit Journal] Type-II InAs/GaSb superlattices (T2SLs) has drawn a lot of attention since it was introduced in 1970, especially for infrared detection as a system of multi-interacting quantum wells. In recent years, T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process, which elevated the performances of T2SL-based photo-detectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). As a pioneer in the field, center for quantum devices (CQD) has been involved in growth, design, characterization, and introduction of T2SL material system for infrared photodetection. In this review paper, we will present the latest development of bias-selectable multi-band infrared photodetectors at the CQD, based on InAs/GaSb/AlSb and InAs/InAs1-xSbx type-II superlattice. [reprint (PDF)]
18.	Dual section quantum cascade lasers with wide electrical tuning S. Slivken, N. Bandyopadhyay, S. Tsao, S. Nida, Y. Bai, Q.Y. Lu and M. Razeghi SPIE Proceedings, Vol. 8631, p. 86310P-1, Photonics West, San Francisco, CA-- February 3, 2013 ...[Visit Journal] This paper describes our development efforts at Northwestern University regarding dual-section sampled grating distributed feedback (SGDFB) QCLs. These devices are the same size, but have much wider electrical tuning, than a traditional DFB laser. In this paper, I will show how we have dramatically extended the monolithic tuning range of high power quantum cascade lasers with high side mode suppression. This includes individual laser element tuning of up to 50 cm^-1 and 24 dB average side mode suppression. These lasers are capable of room temperature continuous operation with high power (>100 mW) output. Additionally, we have demonstrated a broad spectral coverage of over 350 cm^-1 on a single chip, which is equivalent to 87.5% of the gain bandwidth. The eventual goal is to realize an extended array of such laser modules in order to continuously cover a similar or broader spectral range, similar to an external cavity device without any external components. [reprint (PDF)]
18.	High performance InGaAs/InGaP quantum dot infrared photodetector achieved through doping level optimization S. Tsao, K. Mi, J. Szafraniec, W. Zhang, H. Lim, B. Movaghar, and M. Razeghi SPIE Conference, Jose, CA, Vol. 5732, pp. 334-- January 22, 2005 ...[Visit Journal] We report an InGaAs/InGaP/GaAs quantum dot infrared photodetector grown by metalorganic chemical vapor deposition with detectivity of 1.3x10¹¹ cm·Hz^½/W at 77K and 1.2x10¹⁰ ccm·Hz^½/W at 120K. Modeling of the Quantum dot energy levels showed us that increased photoresponse could be obtained by doping the quantum dots to 4 electrons per dot instead of the usual 2 electrons per dot. This happens because the primary photocurrent transition is from the first excited state to a higher excited state. Increasing the quantum doping in our device yielded significant responsivity improvement and much higher detectivity as a result. This paper discusses the performance of this higher doping device and compares it to our previously reported device with lower doping. [reprint (PDF)]
18.	High Power Mid-Infrared Quantum Cascade Lasers Grown on Si Steven Slivken, Nirajman Shrestha, and Manijeh Razeghi Photonics, vol. 9, 626 ...[Visit Journal] This article details the demonstration of a strain-balanced, InP-based mid-infrared quantum cascade laser structure that is grown directly on a Si substrate. This is facilitated by the creation of a metamorphic buffer layer that is used to convert from the lattice constant of Si (0.543 nm) to that of InP (0.587 nm). The laser geometry utilizes two top contacts in order to be compatible with future large-scale integration. Unlike previous reports, this device is capable of room temperature operation with up to 1.6 W of peak power. The emission wavelength at 293 K is 4.82 um, and the device operates in the fundamental transverse mode. [reprint (PDF)]
18.	Ga₂O₃ Metal-oxide-semiconductor Field Effect Transistors on Sapphire Substrate by MOCVD Ji-Hyeon Park, Ryan McClintock and Manijeh Razeghi Semiconductor Science and Technology, Volume 34, Number 8-- June 26, 2019 ...[Visit Journal] Si-doped gallium oxide (Ga₂O₃) thin films were grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD) and fabricated into metal oxide semiconductor field effect transistors (MOSFETs). The Ga₂O₃ MOSFETs exhibited effective gate modulation of the drain current with a complete channel pinch-off for VG < −25 V, and the three-terminal off-state breakdown voltage was 390 V. The device shows a very low gate leakage current (~50 pA/mm), which led to a high on/off ratio of ~10⁸. These transistor characteristics were stable from room temperature to 250 °C [reprint (PDF)]
18.	High-Performance Type-II InAs/GaSb Superlattice Photodiodes with Cutoff Wavelength Around 7 µm Y. Wei, A. Hood, H. Yau, V. Yazdanpanah, M. Razeghi, M.Z. Tidrow and V. Nathan Applied Physics Letters, 86 (9)-- February 28, 2005 ...[Visit Journal] We report the most recent result in the area of type-II InAs/GaSb superlattice photodiodes that have a cutoff wavelength around 7 µm at 77 K. Superlattice with a period of 40 Å lattice matched to GaSb was realized using Ga_xIn_1–x type interface engineering technique. Compared with significantly longer period superlattices, we have reduced the dark current density under reverse bias dramatically. For a 3 µm thick structure, using sulfide-based passivation, the dark current density reached 2.6×10^–5 A/cm² at –3 V reverse bias at 77 K. At this temperature the photodiodes have R₀A of 9300 Ω·cm² and a thermally limited zero bias detectivity of 1×10¹² cm·Hz^½/W. The 90%–10% cutoff energy width was only 16.5 meV. The devices did not show significant dark current change at 77 K after three months storage in the atmosphere. [reprint (PDF)]
18.	High power, low divergent, substrate emitting quantum cascade ring laser in continuous wave operation D. H. Wu and M. Razeghi APL Materials 5, 035505-- March 21, 2017 ...[Visit Journal] We demonstrate a surface grating coupled substrate emitting quantum cascade ring laser with high power room temperature continuous wave operation at 4.64 μm μm . A second order surface metal/semiconductor distributed-feedback grating is used for in-plane feedback and vertical out-coupling. A device with 400 μm μm radius ring cavity exhibits an output power of 202 mW in room temperature continuous wave operation. Single mode operation with a side mode suppression ratio of 25 dB is obtained along with a good linear tuning with temperature. The far field measurement exhibits a low divergent concentric ring beam pattern with a lobe separation of ∼0.34°, which indicates that the device operates in fundamental mode (n = 1). [reprint (PDF)]
18.	Quantum Dot Infrared Photodetectors: Comparison Experiment and Theory H. Lim, W. Zhang, S. Tsao, T. Sills, J. Szafraniec, K. Mi, B. Movaghar, and M. Razeghi Physical Review B, 72-- August 17, 2005 ...[Visit Journal] We present data and calculations and examine the factors that determine the detectivities in self-assembled InAs and InGaAs based quantum dot infrared photodetectors (QDIPs). We investigate a class of devices that combine good wavelength selectivity with “high detectivity.” We study the factors that limit the temperature performance of quantum dot detectors. For this we develop a formalism to evaluate the optical absorption and the electron transport properties. We examine the performance limiting factors and compare theory with experimental data. We find that the notion of a phonon bottleneck does not apply to large-diameter lenslike quantum dots, which have many closely spaced energy levels. The observed strong decrease of responsivity with temperature is ultimately due to a rapid thermal cascade back into the ground states. High temperature performance is improved by engineering the excited state to be near the continuum. The good low temperature (77 K) performance in strongly bound QDIPs is shown to be due to the high gain and the low noise achievable in these micron size devices. [reprint (PDF)]
18.	Demonstration of high performance bias-selectable dual-band short-/mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices A.M. Hoang, G. Chen, A. Haddadi and M. Razeghi Applied Physics Letters, Vol. 102, No. 1, p. 011108-1-- January 7, 2013 ...[Visit Journal] High performance bias-selectable dual-band short-/mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattice with designed cut-off wavelengths of 2 μm and 4 μm was demonstrated. At 150 K, the short-wave channel exhibited a quantum efficiency of 55%, a dark current density of 1.0 × 10⁻⁹ A/cm² at −50 mV bias voltage, providing an associated shot noise detectivity of 3.0 × 10¹³ Jones. The mid-wavelength channel exhibited a quantum efficiency of 33% and a dark current density of 2.6 × 10⁻⁵ A/cm² at 300 mV bias voltage, resulting in a detectivity of 4.0 × 10¹¹ Jones. The spectral cross-talk between the two channels was also discussed for further optimization. [reprint (PDF)]
18.	Interface-induced Suppression of the Auger Recombination in Type-II InAs/GaSb Superlattices H. Mohseni, V.I. Litvinov and M. Razeghi Physical Review B 58 (23)-- December 15, 1998 ...[Visit Journal] The temperature dependence of the nonequilibrium carriers lifetime has been deduced from the measurement of the photocurrent response in InAs/GaSb superlattices. Based on the temperature dependence of the responsivity and modeling of the transport parameters we have found that the carrier lifetime weakly depends on temperature in the high-temperature region. This indicates the temperature dependence of the Auger recombination rate with no threshold that differs it from that in the bulk material and can be attributed to the interface-induced suppression of the Auger recombination in thin quantum wells. [reprint (PDF)]
18.	Optoelectronic Integrated Circuits (OEICs) for Next Generation WDM Communications M. Razeghi and S. Slivken SPIE Conference, Boston, MA, -- July 29, 2002 ...[Visit Journal] This paper reviews some of the key enabling technologies for present and future optoelectronic intergrated circuits. This review concentrates mainly on technology for lasers, waveguides, modulators, and fast photodetectors as the basis for next generation communicatiosn systems. Emphasis is placed on intergrations of components and mass production of a generic intelligent tranciever. [reprint (PDF)]
18.	Solar-blind avalanche photodiodes R. McClintock, K. Minder, A. Yasan, C. Bayram, F. Fuchs, P. Kung and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61271D-- January 23, 2006 ...[Visit Journal] There is a need for semiconductor based UV photodetectors to support avalanche gain in order to realize better performance and more effectively compete with existing photomultiplier tubes. However, there are numerous technical issues associated with the realization of high-quality solar-blind avalanche photodiodes (APDs). In this paper, APDs operating at 280 nm, within the solar-blind region of the ultraviolet spectrum, are investigated. [reprint (PDF)]
17.	Graphene versus oxides for transparent electrode applications Sandana, V. E.; Rogers, D. J.; Teherani, F. Hosseini; Bove, P.; Razeghi, M. Proc. SPIE 8626, Oxide-based Materials and Devices IV, 862603 (March 18, 2013)-- March 18, 2013 ...[Visit Journal] Due to their combination of good electrical conductivity and optical transparency, Transparent Conducting Oxides (TCOs) are the most common choice as transparent electrodes for optoelectronics applications. In particular, devices, such as LEDs, LCDs, touch screens and solar cells typically employ indium tin oxide. However, indium has some significant drawbacks, including toxicity issues (which are hampering manufacturing), an increasing rarefication (due to a combination of relative scarcity and increasing demand [1]) and resulting price increases. Moreover, there is no satisfactory option at the moment for use as a p-type transparent contact. Thus alternative materials solutions are actively being sought. This review will compare the performance and perspectives of graphene with respect to TCOs for use in transparent conductor applications. [reprint (PDF)]
17.	Quantum Hall liquid-to-insulator transition in In_1-xGa_xAs/InP heterostructures W. Pan, D. Shahar, D.C. Tsui, H.P. Wei, and M. Razeghi Physical Review B 55 (23)-- June 15, 1997 ...[Visit Journal] We report a temperature- and current-scaling study of the quantum Hall liquid-to-insulator transition in an In_1-xGa_xAs/InP heterostructure. When the magnetic field is at the critical field B_c, ρ_xx=0.86h/e². Furthermore, the transport near B_c scales as \|B- Bc\|T^-κ with κ=0.45±0.05, and as \|B- Bc\|I^-b with b=0.23±0.05. The latter can be due to phonon emission in a dirty piezoelectric medium, or can be the consequence of critical behavior near B_c, within which z=1.0±0.1 and ν=2.1±0.3 are obtained from our data. [reprint (PDF)]
17.	High power InAsSb/InPAsSb/InAs mid-infrared lasers A. Rybaltowski, Y. Xiao, D. Wu, B. Lane, H. Yi, H. Feng, J. Diaz, and M. Razeghi Applied Physics Letters 71 (17)-- October 27, 1997 ...[Visit Journal] We demonstrate high-power InAsSb/InPAsSb laser bars (λ ≈ 3.2 μm) consisting of three 100 μm-wide laser stripes of 700 μm cavity length, with peak output power up to 3 W at 90 K, and far-fields for the direction perpendicular to the junction as narrow as 12° full width half maximum. Spectra and far-field patterns of the laser bars are shown to have excellent characteristics for a wide range of operating conditions, suggesting the possibility of even higher light power emission with good beam quality. Joule heating is shown to be the major factor limiting higher power operation. [reprint (PDF)]
17.	Type-II superlattice-based extended short-wavelength infrared focal plane array with an AlAsSb/GaSb superlattice etch-stop layer to allow near-visible light detection Romain Chevallier, Arash Dehzangi, Abbas Haddadi, and Manijeh Razeghi Optics Letters Vol. 42, Iss. 21, pp. 4299-4302-- October 17, 2017 ...[Visit Journal] A versatile infrared imager capable of imaging the near-visible to the extended short-wavelength infrared (e-SWIR) is demonstrated using e-SWIR InAs/GaSb/AlSb type-II superlattice-based photodiodes. A bi-layer etch-stop scheme consisting of bulk InAs_0.91Sb_0.09 and AlAs_0.1Sb_0.9/GaSb superlattice layers is introduced for substrate removal from the hybridized back-side illuminated photodetectors. The implementation of this new technique on an e-SWIR focal plane array results in a significant enhancement in the external quantum efficiency (QE) in the 1.8–0.8μm spectral region, while maintaining a high QE at wavelengths longer than 1.8μm. Test pixels exhibit 100% cutoff wavelengths of ∼2.1 and ∼2.25μm at 150 and 300K, respectively. They achieve saturated QE values of 56% and 68% at 150 and 300K, respectively, under back-side illumination and without any anti-reflection coating. At 150K, the photodetectors (27μm×27μm area) exhibit a dark current density of 4.7×10⁻⁷ A/cm² under a −50 mV applied bias providing a specific detectivity of 1.77×10¹² cm·Hz^1/2/W. At 300K, the dark current density reaches 6.6×10⁻² A/cm² under −50 mV bias, providing a specific detectivity of 5.17×10⁹ cm·Hz^1/2/W. [reprint (PDF)]
17.	High performance LWIR Type-II InAs/GaSb superlattice photodetectors and infrared focal plane array Y. Wei, A. Hood, A. Gin, V. Yazdanpanah, M. Razeghi and M. Tidrow SPIE Conference, Jose, CA, Vol. 5732, pp. 309-- January 22, 2005 ...[Visit Journal] We report on the demonstration of a focal plane array based on Type-II InAs-GaSb superlattices grown on n-type GaSb substrate with a 50% cutoff wavelength at 10 μm. The surface leakage occurring after flip-chip bonding and underfill in the Type-II devices was suppressed using a double heterostructure design. The R₀A of diodes passivated with SiO₂ was 23 Ω·cm² after underfill. A focal plane array hybridized to an Indigo readout integrated circuit demonstrated a noise equivalent temperature difference of 33 mK at 81 K, with an integration time of 0.23 ms. [reprint (PDF)]
17.	High-power λ ~ 9.5 µm quantum-cascade lasers operating above room temperature in continuous-wave mode J.S. Yu, S. Slivken, A. Evans, S.R. Darvish, J. Nguyen, and M. Razeghi Applied Physics Letters, 88 (9)-- February 27, 2006 ...[Visit Journal] We report high-power continuous-wave (cw) operation of λ~9.5 μm quantum-cascade lasers to a temperature of 318 K. A high-reflectivity-coated 19-μm-wide and 3-mm-long device exhibits cw output powers as high as 150 mW at 288 K and still 22 mW at 318 K. In cw operation at 298 K, a threshold current density of 1.57 kA/cm², a slope efficiency of 391 mW/A, and a maximum wall-plug efficiency of 0.71% are obtained. [reprint (PDF)]
17.	High-Power Continuous-Wave Operation of a 6 µm Quantum-Cascade Laser at Room Temperature J.S. Yu, S. Slivken, A. Evans, L. Doris, and M. Razeghi Applied Physics Letters, 83 (13)-- September 29, 2003 ...[Visit Journal] We report continuous-wave (cw) operation of quantum-cascade lasers (λ= 6 µm) using a thick electroplated Au top contact layer and epilayer-up bonding on a copper heat sink up to a temperature of 308 K (35 °C). The high cw optical output powers of 132 mW at 293 K and 21 mW at 308 K are achieved with threshold current densities of 2.29 and 2.91 kA/cm², respectively, for a high-reflectivity-coated 15 µm wide and 2 mm long laser. [reprint (PDF)]
17.	1.2–1.6 μm GaxIn1−xAsyP1−y-InP DH lasers grown by LPMOCVD M. Razeghi, B. de Crémoux, J.P. Duchemin M. Razeghi, B. de Crémoux, J.P. Duchemin, 1.2–1.6 μm GaxIn1−xAsyP1−y-InP DH lasers grown by LPMOCVD, Journal of Crystal Growth, Volume 68, Issue 1, 1984, Pages 389-397,-- September 1, 1984 ...[Visit Journal] Room temperature pulse operation and continuous wave (CW) operation in the 1.2–1.6 μm region have been achieved in GaInAsP-InP DH lasers fabricated on material grown by LPMOCVD. Threshold currents density as low as 430 A/cm2 (cavity length of 950 μm) have been measured for devices emitting at 1.3 μm. Threshold current densities of 1060 A/cm2 (cavity length of 400 μm) have been obtained for devices emitting at 1.55 μm, with active layer thicknesses of 0.22 μm. Values of T0 between 60 and 70 K have been obtained. Fundamental transverse mode oscillation has been achieved (for CW operation) up to an output power of 10 mW. The preliminary results on the aging test are most encouraging and demonstrate that the LPMOCVD lasers emitting at 1.2–1.6 μm have comparable degradation rates to those of LPE lasers suggesting the LPMOCVD technique is promising for large scale production of laser diodes. [reprint (PDF)]
17.	New design strategies for multifunctional and inexpensive quantum cascade lasers Steven Slivken; Manijeh Razeghi Proc. SPIE 10926, Quantum Sensing and Nano Electronics and Photonics XVI, 1092611-- February 1, 2019 ...[Visit Journal] This manuscript describes some of the new advances in active mid-infrared photonic integrated circuits enabled by new quantum cascade laser technologies. This includes monolithic beam steering which was achieved via the integration of a widely tunable QCL and a tapered grating outcoupler. A record 17.9 degrees of steering with a low divergence beam (0.5 degrees) was achieved. In addition, the use of surface emitting architectures is proposed as a means to reduce the manufacturing cost of next-generation QCLs. A reflective outcoupler is demonstrated which can allow for stable surface emission from a quantum cascade laser and has potential for cost-effective wafer-scale manufacturing. This outcoupler is integrated with an amplified, electrically tunable laser architecture to demonstrate high power surface emission at a wavelength near 4.9 μm. Single mode peak power up to 6.7 W is demonstrated with >6 W available over a 90 cm⁻¹ (215 nm) spectral range. All of this is achieved while maintaining a high quality output beam, similar to a standard edge emitter. [reprint (PDF)]

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