Center for Quantum Devices - Most Downloaded Journal Articles

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1.	Growth and Characterization of Very Long Wavelength Type-II Infrared Detectors H. Mohseni, A. Tahraoui, J. Wojkowski, M. Razeghi, W. Mitchel, and A. Saxler SPIE Conference, San Jose, CA, -- January 26, 2000 ...[Visit Journal] We report on the growth and characterization of type-II IR detectors with a InAs/GaSb superlattice active layer in the 15-19 μm wavelength range. The material was grown by molecular beam epitaxy on semi-insulating GaAs substrates. The material was processed into photoconductive detectors using standard photolithography, dry etching, and metalization. The 50 percent cut-off wavelength of the detectors is about 15.5 μm with a responsivity of 90 mA/W at 80 K. The 90 percent-10 percent cut-off energy width of the responsivity is only 17 meV which is an indication of the uniformity of the superlattices. These are the best reported values for type-II superlattices grown on GaAs substrates. [reprint (PDF)]
1.	Antimonide-Based Type II Superlattices: A Superior Candidate for the Third Generation of Infrared Imaging Systems M. Razeghi, A. Haddadi, A.M. Hoang, G. Chen, S. Bogdanov, S.R. Darvish, F. Callewaert, P.R. Bijjam, and R. McClintock Journal of ELECTRONIC MATERIALS, Vol. 43, No. 8, 2014-- August 1, 2014 ...[Visit Journal] Type II superlattices (T2SLs), a system of interacting multiquantum wells,were introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention, especially for infrared detection and imaging. In recent years, the T2SL material system has experienced incredible improvements in material growth quality, device structure design, and device fabrication techniques that have elevated the performance of T2SL-based photodetectors and focal-plane arrays (FPAs) to a level comparable to state-of-the-art material systems for infrared detection and imaging, such as mercury cadmium telluride compounds. We present the current status of T2SL-based photodetectors and FPAs for imaging in different infrared regimes, from short wavelength to very long wavelength, and dual-band infrared detection and imaging, as well as the future outlook for this material system. [reprint (PDF)]
1.	Midinfrared Semiconductor Photonics – A Roadmap:Quantum Cascade Lasers MANIJEH RAZEGHI arXiv:2511.03868 [physics.optics] ...[Visit Journal] Mid-wave infrared (IR) quantum cascade lasers (QCLs) offer high output power, excellent efficiency, broad wavelength tunability, and elevated operating temperatures, especially when operating in the 3–12 μm wavelength range. These characteristics make them highly promising for a wide range of applications, including high-resolution molecular spectroscopy, ultra-low-loss optical fiber communications using fluoride-based glasses (with attenuation below 2.5×10⁻⁴ dB/km), trace gas detection, air pollution monitoring (as many molecules, particularly hydrocarbons, exhibiting strong absorption lines in this spectral region), and medical diagnostics. This article presents a comprehensive overview of the development of QCLs, highlighting key milestones, the current state of the technology, and future directions, framed within the broader context of the Semiconductor Mid-Infrared Photonics Roadmap.
1.	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)]
1.	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)]
1.	Room temperature quantum cascade lasers with 27% wall plug efficiency Y. Bai, N. Bandyopadhyay, S. Tsao, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 98, No. 18, p. 181102-1-- May 3, 2011 ...[Visit Journal] Using the recently proposed shallow-well design, we demonstrate InP based quantum cascade lasers (QCLs) emitting around 4.9 μm with 27% and 21% wall plug efficiencies in room temperature (298 K) pulsed and continuous wave (CW) operations, respectively. The laser core consists of 40 QCL-stages. The highest cw efficiency is obtained from a buried-ridge device with a ridge width of 8 μm and a cavity length of 5 mm. The front and back facets are antireflection and high-reflection coated, respectively. The maximum single facet cw power at room temperature amounts to 5.1 W. [reprint (PDF)]
1.	Sb-based infrared materials and photodetectors for the near room temperature applications J.D. Kim, E. Michel, H. Mohseni, J. Wojkowski, J.J. Lee and M. Razeghi SPIE Conference, San Jose, CA, Vol. 2999, pp. 55-- February 12, 1997 ...[Visit Journal] We report on the growth of InSb, InAsSb, and InTlSb alloys for infrared photodetector applications. The fabrication and characterization of photodetectors based on these materials are also reported. Both photoconductive and photovoltaic devices are investigated. The materials and detector structures were grown on (100) and (111)B semi-insulating GaAs and GaAs coated Si substrates by low pressure metalorganic chemical vapor deposition and solid source molecular beam epitaxy. Photoconductive detectors fabricated from InAsSb and InTlSb have been operated in the temperature range from 77 K to 300 K. The material parameters for photovoltaic device structures have been optimized through theoretical calculations based on fundamental mechanisms. InSb p-i-n photodiodes with 77 K peak responsivities approximately 103 V/W were grown on Si and (111) GaAs substrates. An InAsSb photovoltaic detector with a composition of x equals 0.85 showed photoresponse up to 13 micrometers at 300 K with a peak responsivity of 9.13 X 10-2 V/W at 8 micrometers . The RoA product of InAsSb detectors has been theoretically and experimentally analyzed. [reprint (PDF)]
1.	Optimizing facet coating of quantum cascade lasers for low power consumption Y. Bai, S.R. Darvish, N. Bandyopadhyay, S. Slivken and M. Razeghi Journal of Applied Physics, Vol. 109, No. 5, p. 053103-1-- March 1, 2011 ...[Visit Journal] Typical high power consumption (∼10 W) of mid-infrared quantum cascade lasers (QCLs) has been a serious limitation for applications in battery powered systems. A partial high-reflection (PHR) coating technique is introduced for power downscaling with shorter cavity lengths. The PHR coating consists of a double layer dielectric of SiO₂ and Ge. With this technique, a 4.6 μm QCL with an ultra low threshold power consumption of less than a watt (0.83 W) is demonstrated in room temperature continuous wave operation. At 25°C, the maximum output power and wall plug efficiency are 192 mW and 8.6%, respectively. [reprint (PDF)]
1.	Cubic Phase GaN on Nano-grooved Si (100) via Maskless Selective Area Epitaxy Bayram, C., Ott, J. A., Shiu, K.-T., Cheng, C.-W., Zhu, Y., Kim, J., Razeghi, M. and Sadana, D. K. Adv. Funct. Mater. 2014-- April 1, 2014 ...[Visit Journal] A method of forming cubic phase (zinc blende) GaN (referred as c-GaN) on a CMOS-compatible on-axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h-GaN) and possess very high polarization fields (∼MV/cm) along the common growth direction of <0001>. Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization-free along the common growth direction of <001>, however, this phase is thermodynamically unstable, requiring low-temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano-groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress-free, and low-defectivity c-GaN on CMOS-compatible on-axis Si. These results suggest that epitaxial growth conditions and nano-groove pattern parameters are critical to obtain such high quality c-GaN. InGaN/GaN multi-quantum-well structures grown on c-GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology. [reprint (PDF)]
1.	Highly temperature insensitive quantum cascade lasers Y. Bai, N. Bandyopadhyay, S. Tsao, E. Selcuk, S. Slivken and M. Razeghi Applied Physics Letters, Vol. 97, No. 25-- December 20, 2010 ...[Visit Journal] An InP based quantum cascade laser (QCL) heterostructure emitting around 5 μm is grown with gas-source molecular beam epitaxy. The QCL core design takes a shallow-well approach to maximize the characteristic temperatures, T(0) and T(1), for operations above room temperature. A T(0) value of 383 K and a T(1) value of 645 K are obtained within a temperature range of 298–373 K. In room temperature continuous wave operation, this design gives a single facet output power of 3 W and a wall plug efficiency of 16% from a device with a cavity length of 5 mm and a ridge width of 8 μm. [reprint (PDF)]
1.	Low frequency noise in 1024 x 1024 long wavelength infrared focal plane array base on Type-II InAs/GaSb superlattice A. Haddadi, S.R. Darvish, G. Chen, A.M. Hoang, B.M. Nguyen and M. Razeghi SPIE Proceedings, Vol. 8268, p. 82680X-- January 22, 2012 ...[Visit Journal] Recently, the type-II InAs/GaSb superlattice (T2SL) material platform is considered as a potential alternative for HgCdTe technology in long wavelength infrared (LWIR) imaging. This is due to the incredible growth in the understanding of its material properties and improvement of device processing which leads to design and fabrication of better devices. In this paper, we report electrical low frequency noise measurement on a high performance type-II InAs/GaSb superlattice 1024×1024 LWIR focal plane array. [reprint (PDF)]
1.	Thin-Film Antimonide-Based Photodetectors Integrated on Si Yiyun Zhang , Member, IEEE, Abbas Haddadi, Member, IEEE, Romain Chevallier, Arash Dehzangi, Member, IEEE, and Manijeh Razeghi , Life Fellow, IEEE IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 54, NO. 2-- April 1, 2018 ...[Visit Journal] Monolithic integration of antimonide (Sb)-based compound semiconductors on Si is in high demand to enrich silicon photonics by extending the detection range to longer infrared wavelengths. In this paper, we have demonstrated the damage-free transfer of large-area (1×1 cm² ) narrow-bandgap Sb-based type-II superlattice (T2SL)-based thin-film materials onto a Si substrate using a combination of wafer-bonding and chemical epilayer release techniques. An array of Sb-based T2SL-based long-wavelength infrared (LWIR) photodetectors with diameters from 100 to 400 μm has been successfully fabricated using standard "top–down" processing technique. The transferred LWIR photodetectors exhibit a cut-off wavelength of λ 8.6 μm at 77 K. The dark current density of the transferred photodetectors under 200 mV applied bias at 77 K is as low as 5.7×10⁻⁴ A/cm² and the R×A reaches 66.3 Ω·cm², exhibiting no electrical degradation compared with reference samples on GaSb native substrate. The quantum efficiency and peak responsivity at 6.75 μm (@77 K, 200 mV) are 46.2% and 2.44 A/W, respectively. The specific detectivity (D^*) at 6.75 μm reaches as high as 1.6×10¹¹ cm·Hz^1/2/W under 200 mV bias at 77 K. Our method opens a reliable pathway to realize high performance and practical Sb-based optoelectronic devices on a Si platform. [reprint (PDF)]
1.	Planar nBn type-II superlattice mid-wavelength infrared photodetectors using zinc ion-implantation Arash Dehzangi, Donghai Wu, Ryan McClintock, Jiakai Li, and Manijeh Razeghi Appl. Phys. Lett. 116, 221103 https://doi.org/10.1063/5.0010273-- June 2, 2020 ...[Visit Journal] In this Letter, we report the demonstration of zinc ion-implantation to realize planar mid-wavelength infrared photodetectors based on type-II InAs/InAs1−xSbx superlattices. At 77 K, the photodetectors exhibit a peak responsivity of 0.68 A/W at 3.35 μm, corresponding to a quantum efficiency of 23.5% under Vb = −80 mV, without anti-reflection coating; these photodetectors have a 100% cutoff wavelength of 4.28 μm. With an R0 × A value of 1.53 × 104 Ω cm2 and a dark current density of 1.23 × 10−6 A/cm2 under an applied bias of −80 mV at 77 K, the photodetectors exhibit a specific detectivity of 9.12 × 1011 cm·Hz1/2/W. [reprint (PDF)]
1.	Evaluating the size-dependent quantum efficiency loss in a SiO₂-Y₂O₃hybrid gated type-II InAs/GaSb long-infrared photodetector array G. Chen , A. M. Hoang , and M. Razeghi Applied Physics Letters 104 , 103509 (2014)-- March 14, 2014 ...[Visit Journal] Growing Y₂O₃ on 20 nm SiO₂ to passivate a 11 μm 50% cut-off wavelength long-wavelength infrared type-II superlattice gated photodetector array reduces its saturated gate bias (VG_sat ) to −7 V. Size-dependent quantum efficiency (QE) losses are evaluated from 400 μm to 57 μm size gated photodiode. Evolution of QE of the 57 μm gated photodiode with gate bias and diode operation bias reveals different surface recombination mechanisms. At 77 K and VG,sat , the 57 μm gated photodiode exhibits QE enhancement from 53% to 63%, and it has 1.2 × 10⁻⁵ A/cm² dark current density at −200 mV, and a specific detectivity of 2.3 × 10¹² Jones. [reprint (PDF)]
1.	Demonstration of shortwavelength infrared photodiodes based on type-II InAs/GaSb/AlSb superlattices A.M. Hoang, G. Chen, A. Haddadi, S. Abdollahi Pour, and M. Razeghi Applied Physics Letters, Vol. 100, No. 21, p. 211101-1-- May 21, 2012 ...[Visit Journal] We demonstrate the feasibility of the InAs/GaSb/AlSb type-II superlattice photodiodes operating at the short wavelength infrared regime below 3 μm. An n-i-p type-II InAs/GaSb/AlSb photodiode was grown with a designed cut-off wavelength of 2 μm on a GaSb substrate. At 150 K, the photodiode exhibited a dark current density of 5.6 × 10⁻⁸ A/cm² and a front-side-illuminated quantum efficiency of 40.3%, providing an associated shot noise detectivity of 1.0 × 10¹³ Jones. The uncooled photodiode showed a dark current density of 2.2 × 10⁻³ A/cm² and a quantum efficiency of 41.5%, resulting in a detectivity of 1.7 × 10¹⁰ Jones [reprint (PDF)]
1.	Review of high power frequency comb sources based on InP From MIR to THZ at CQD Manijeh Razeghi, Quanyong Lu, Donghai Wu, Steven Slivken Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States-- September 14, 2018 ...[Visit Journal] We present the recent development of high performance compact frequency comb sources based on mid-infrared quantum cascade lasers. Significant performance improvements of our frequency combs with respect to the continuous wave power output, spectral bandwidth, and beatnote linewidth are achieved by systematic optimization of the device's active region, group velocity dispersion, and waveguide design. To date, we have demonstrated the most efficient, high power frequency comb operation from a free-running room temperature continuous wave (RT CW) dispersion engineered QCL at λ~5-9 μm. In terms of bandwidth, the comb covered a broad spectral range of 120 cm⁻¹ with a radio-frequency intermode beatnote spectral linewidth of 40 Hz and a total power output of 880 mW at 8 μm and 1 W at ~5.0 μm. The developing characteristics show the potential for fast detection of various gas molecules. Furthermore, THz comb sources based on difference frequency generation in a mid-IR QCL combs could be potentially developed. [reprint (PDF)]
1.	Persistent photoconductivity and the quantized Hall effect in In0.53Ga0.47As/InP heterostructures H. P. Wei; D. C. Tsui; M. Razeghi H. P. Wei, D. C. Tsui, M. Razeghi; Persistent photoconductivity and the quantized Hall effect in In0.53Ga0.47As/InP heterostructures. Appl. Phys. Lett. 15 September 1984; 45 (6): 666–668.-- September 15, 1984 ...[Visit Journal] A persistent photoconductivity is observed in the transport of the high mobility two‐dimensional electron gas in In0.53Ga0.47 As/InP heterostructures. Low field Hall measurements from 300 to 4.2 K and the quantized Hall effect in the high field limit are studied with radiation from visible and infrared light‐emitting diodes. Our results demonstrate conclusively that the effect is due to photogeneration of electron‐hole pairs in the heterostructure and trapping of holes in the In0.53Ga0.47 As. [reprint (PDF)]
1.	Comparison of the Physical Properties of GaN Thin Films Deposited on (0112) and (0001) Sapphire Substrates C.J. Sun and M. Razeghi Applied Physics Letters 63 (7)-- August 16, 1993 ...[Visit Journal] A direct comparison of the physical properties of GaN thin films is made as a function of the choice of substrate orientations. Gallium nitride single crystals were grown on (0001) and (0112) sapphire substrates by metalorganic chemical vapor deposition. Better crystallinity with fine ridgelike facets is obtained on the (0112) sapphire. Also lower carrier concentration and higher mobilities indicate both lower nitrogen vacancies and less oxygen incorporation on the (0112) sapphire. The results of this study show better physical properties of GaN thin films achieved on (0112) sapphire. [reprint (PDF)]
1.	Low-Threshold 7.3 μm Quantum Cascade Lasers Grown by Gas-Source Molecular Beam Epitaxy S. Slivken, A. Matlis, A. Rybaltowski, Z. Wu and M. Razeghi Applied Physics Letters 74 (19)-- May 19, 1999 ...[Visit Journal] We report low-threshold 7.3 μm superlattice-based quantum cascade lasers. The threshold current density is 3.4 kA/cm² at 300 K and 1.25 kA/cm² at 79 K in pulsed mode for narrow (∼20 μm), 2 mm-long laser diodes. The characteristic temperature (T₀) is 210 K. The slope efficiencies are 153 and 650 mW/A at 300 and 100 K, respectively. Power output is in excess of 100 mW at 300 K. Laser far-field intensity measurements give divergence angles of 64° and 29° in the growth direction and in the plane of the quantum wells, respectively. Far-field simulations show excellent agreement with the measured results. [reprint (PDF)]
1.	Techniques for High-Quality SiO₂ Films J. Nguyen and M. Razeghi SPIE Conference, January 25-29, 2007, San Jose, CA Proceedings – Quantum Sensing and Nanophotonic Devices IV, Vol. 6479, p. 64791K-1-8-- January 29, 2007 ...[Visit Journal] We report on the comparison of optical, structural, and electrical properties of SiO₂ using plasma-enhanced chemical vapor deposition and ion-beam sputtering deposition. High-quality, low-temperature deposition of SiO₂ by ion-beam sputtering deposition is shown to have lower absorption, smoother and more densely packed films, a lower amount of fixed oxide charges, and a lower trapped-interface density than SiO₂ by plasma-enhanced chemical vapor deposition. This high-quality SiO₂ is then demonstrated as an excellent electrical and mechanical surface passivation layer on Type-II InAs/GaSb photodetectors [reprint (PDF)]
1.	High-speed short wavelength infrared heterojunction phototransistors based on type II superlattices Jiakai Li; Arash Dehzangi; Donghai Wu; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128813-- January 31, 2020 ...[Visit Journal] A two terminal short wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb on GaSb substrate are designed fabricated and presented. With the base thickness of 40 nm, the device exhibited 100% cut-off wavelengths of ~2.3 μm at 300K. The saturated peak responsivity value is of 325.5 A/W at 300K, under front-side illumination without any anti-reflection coating. A saturated optical gain at 300K was 215 a saturated dark current shot noise limited specific detectivity of 4.9×10¹¹ cm·Hz^½/W at 300 K was measured. Similar heterojunction phototransistor structure was grown and fabricated with different method of processing for high speed testing. For 80 μm diameter circular diode size under 20 V applied reverse bias, a −3 dB cut-off frequency of 1.0 GHz was achieved, which showed the potential of type-II superlattice based heterojunction phototransistors to be used for high speed detection. [reprint (PDF)]

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