Center for Quantum Devices - Most Downloaded Journal Articles

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70.	-- November 30, 1999
68.	nBn extended short-wavelength infrared focal plane array ARASH DEHZANGI, ABBAS HADDADI, ROMAIN CHEVALLIER, YIYUN ZHANG, AND MANIJEH RAZEGHI Optics Letters Vol. 43, Issue 3, pp. 591-594-- February 1, 2018 ...[Visit Journal] An extended short-wavelength nBn InAs/GaSb/AlSb type-II superlattice-based infrared focal plane array imager was demonstrated. A newly developed InAs_0.10Sb_0.90∕GaSb superlattice design was used as the large-bandgap electron barrier in this photodetector. The large band gap electron-barrier design in this nBn photodetector architecture leads to the device having lower dark current densities. A new bi-layer etch-stop scheme using a combination of InAs_0.91Sb_0.09 bulk and AlAs_0.1Sb_0.9∕GaSb superlattice layers was introduced to allow complete substrate removal and a shorter wavelength cut-on. Test pixels exhibit 100% cutoff wavelengths of ∼2.30 and ∼2.48 μm at 150 and 300 K, respectively. The devices achieve saturated quantum efficiency values of 59.7% and 63.8% at 150 and 300 K, respectively, under backside illumination and without any antireflection coating.At 150 K, photodetectors exhibit dark current density of 8.75 × 10⁻⁸ A∕cm² under −400 mV applied bias, providing specific detectivity of 2.82 × 10¹² cm · Hz^1∕2∕W at 1.78 μm. At 300 K, the dark current density reaches 4.75 × 10⁻² A∕cm² under −200 mV bias, providing a specific detectivity of 8.55 × 10⁹ cm · Hz^1∕2∕W 1.78 μm. [reprint (PDF)]
68.	Band-structure-engineered high-gain LWIR photodetector based on a type-II superlattice Arash Dehzangi, Jiakai Li and Manijeh Razeghi Light: Science & Applications volume 10, Article number: 17 (2021) https://doi.org/10.1038/s41377-020-00453-x ...[Visit Journal] The LWIR and longer wavelength regions are of particular interest for new developments and new approaches to realizing long-wavelength infrared (LWIR) photodetectors with high detectivity and high responsivity. These photodetectors are highly desirable for applications such as infrared earth science and astronomy, remote sensing, optical communication, and thermal and medical imaging. Here, we report the design, growth, and characterization of a high-gain band-structure-engineered LWIR heterojunction phototransistor based on type-II superlattices. The 1/e cut-off wavelength of the device is 8.0 µm. At 77 K, unity optical gain occurs at a 90 mV applied bias with a dark current density of 3.2 × 10−7 A/cm2. The optical gain of the device at 77 K saturates at a value of 276 at an applied bias of 220 mV. This saturation corresponds to a responsivity of 1284 A/W and a specific detectivity of 2.34 × 1013 cm Hz1/2/W at a peak detection wavelength of ~6.8 µm. The type-II superlattice-based high-gain LWIR device shows the possibility of designing the high-performance gain-based LWIR photodetectors by implementing the band structure engineering approach. [reprint (PDF)]
59.	Ga2O3/(Al)GaN Heterostructures for Next Generation Power Electronics Manijeh Razeghi, N. Shrestha, V. E. Sandana, D. J. Rogers, F. H. Teherani physica status solidi (b), 2026; 263:e70213 Gallium oxide (Ga2O3) is an emerging semiconductor for high-power electronics, but its low thermal conductivity, lack of viable p-type doping, and limited carrier mobility restrict device performance and prevent high-speed applications. This work presents a novel strategy to simultaneously mitigate the thermal and transport limitations of Ga2O3 through heterojunctions with III-nitride materials. Owing to their higher thermal conductivity and strong polarization fields, III-nitrides can enhance heat dissipation and enable high-density two-dimensional electron gases (2DEGs) at the heterointerface, improving switching speed. The role of spontaneous and piezoelectric polarization in 2DEG formation is systematically examined. It is shown that Al-polar AlN/β-Ga2O3 heterojunctions do not support 2DEG formation due to hole accumulation at the interface, whereas N-polar AlN/β-Ga2O3 heterostructures are identified as promising candidates for high 2DEG densities. The band alignment of the AlN/β-Ga2O3 interface is also investigated. Additionally, κ-Ga2O3, recently identified as ferroelectric with strong polarization, is explored in κ-Ga2O3/AlGaN heterostructures. Using epitaxial layer and strain engineering, electron mobilities up to 691 cm2 V−1 s −1 at 77 K were achieved in MOCVD-grown κ-Ga2O3/N-polar AlGaN/AlN heterostructures. These results highlight the potential of III-nitride/Ga2O3 heterostructures for high-power and radiofrequency device applications with enhanced performance and efficiency. [reprint (PDF)]
40.	Electro-thermal breakdown in p-NiO/n-Ga2O3 heterojunction power diodes: evidence for the role of heat extraction via sapphire S. Kubsky, Z. Berger, M. Chevrot, D. J. Rogers, V. E. Sandana, F. Hosseini Teherani, N. De France, M. Lesecq, Z. Bougrioua, M. Razeghi Proc. of SPIE Vol. PC13897, PC138970X · 2026 ...[Visit Journal] Gallium oxide (Ga₂O₃) is attracting strong interest for next-generation power electronics due to its ultra-wide bandgap and large critical breakdown field; however, device performance is frequently constrained by self-heating arising from its relatively low and anisotropic thermal conductivity. In this work, the electrical and thermal behaviour of p-NiO/n-Ga₂O₃ heterojunction diodes grown by pulsed laser deposition on r-plane sapphire substrates is investigated under high-bias operation. Identical ring-mesa devices were mounted either on a thermally insulating support or on a metal heat sink, enabling a direct comparison of electro-thermal behaviour. While both configurations exhibit rectifying I–V characteristics, heat-sunk devices show reduced surface temperature rise, suppressed reverse leakage, and a significantly higher breakdown voltage (~ +2150 V) compared with devices measured without effective heat extraction (~ +1600 V). The results demonstrate that electro-thermal runaway, rather than intrinsic junction limitations, governs breakdown in these thin-film Ga₂O₃ heterojunctions, highlighting thermal management and thermal boundary conditions as key design parameters for high-voltage Ga₂O₃ power devices. [reprint (PDF)]
34.	-- November 30, 1999
32.	Room temperature operation of Ge/SixGe1−x−ySny terahertz quantum cascade lasers predicted using extended combined resonant tunneling and rate equation model Zhou Li,, Zhichao Chen, Baiqi Zhang, Qiyun Lai, Zhanfeng Jiang, Yaoyao Liang Yulong Fan, Haoxiang Li, Qi Qin, Manijeh Razeghi∗, and Feihu Wang∗ Room temperature operation of Ge/SixGe1−x−ySny terahertz quantum cascade lasers predicted using extended combined resonant tunneling and rate equation model ...[Visit Journal] Raising operation temperature of terahertz (THz) quantum cascade lasers (QCLs) to room temperature remains a key challenge in QCL community. Group-IV semiconductors are believed to be a promising solution to this problem since the polar phonon–electron scattering is negligible at elevated temperature. Here, we develop a theoretical model for THz QCL development. This model is established on the combined resonant tunneling and rate equation framework and is extended to be applicable for group-IV QCL design through introducing new scattering mechanisms and continuum states carrier leakage. A two-well THz QCL based on a direct phonon extraction strategy is designed and predicted to be capable of working above 300 K. This result lays the foundation for future room temperature THz QCL devices development using group-IV semiconductors. [reprint (PDF)]
26.	High-power, high-wall-plug-efficiency quantum cascade lasers with high-brightness in continuous wave operation at 3–300μm Manijeh Razeghi, Yanbo Bai and Feihu Wang Razeghi et al. Light: Science & Applications (2025) 14:252 ...[Visit Journal] Quantum cascade lasers (QCLs) are unipolar quantum devices based on inter-sub-band transitions. They break the electron-hole recombination mechanism in traditional semiconductor lasers, overcome the long-lasting bottleneck which is that the emission wavelength of semiconductor laser is completely dependent on the bandgap of semiconductor materials. Therefore, their emission wavelength is able to cover the mid-infrared (mid-IR) range and the “Terahertz gap” that is previously inaccessible by any other semiconductor lasers. [reprint (PDF)]
24.	High Carrier Lifetime InSb Grown on GaAs Substrates E. Michel, H. Mohseni, J.D. Kim, J. Wojkowski, J. Sandven, J. Xu, M. Razeghi, R. Bredthauer, P. Vu, W. Mitchel, and M. Ahoujja Applied Physics Letters 71 (8-- August 25, 1997 ...[Visit Journal] We report on the growth of near bulklike InSb on GaAs substrates by molecular beam epitaxy despite the 14% lattice mismatch between the epilayer and the substrate. Structural, electrical, and optical properties were measured to assess material quality. X-ray full widths at half-maximum were as low as 55 arcsec for a 10 µm epilayer, peak mobilities as high as ~ 125 000 cm2/V s, and carrier lifetimes up to 240 ns at 80 K. [reprint (PDF)]
24.	Demonstration of long wavelength infrared Type-II InAs/InAs_1-xSb_x superlattices photodiodes on GaSb substrate grown by metalorganic chemical vapor deposition D. H. Wu, A. Dehzangi, Y. Y. Zhang, M. Razeghi Applied Physics Letters 112, 241103-- June 12, 2018 ...[Visit Journal] We report the growth and characterization of long wavelength infrared type-II InAs/InAs_1−xSb_x superlattices photodiodes with a 50% cut-off wavelength at 8.0 μm on GaSb substrate grown by metalorganic chemical vapor deposition. At 77 K, the photodiodes exhibited a differential resistance at zero bias (R₀A) 8.0 Ω·cm², peak responsivity of 1.26 A/W corresponding to a quantum efficiency of 21%. A specific detectivity of 5.4×10¹⁰ cm·Hz^1/2/W was achieved at 7.5 μm. [reprint (PDF)]
24.	High brightness angled cavity quantum cascade lasers D. Heydari, Y. Bai, N. Bandyopadhyay, S. Slivken, and M. Razeghi Applied Physics Letters 106, 091105-- March 6, 2015 ...[Visit Journal] A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm²·sr^-1 is obtained, which marks the brightest QCL to date. [reprint (PDF)]
23.	Ultrafast Pulse Generation from Quantum Cascade Lasers Feihu Wang, Xiaoqiong Qi, Zhichao Chen, Manijeh Razeghi, and Sukhdeep Dhillon Wang, F.; Qi, X.; Chen, Z.; Razeghi, M.; Dhillon, S. Ultrafast Pulse Generation from Quantum Cascade Lasers. Micromachines 2022, 13, 2063. https://doi.org/10.3390/ mi13122063 ...[Visit Journal] Quantum cascade lasers (QCLs) have broken the spectral barriers of semiconductor lasers and enabled a range of applications in the mid-infrared (MIR) and terahertz (THz) regimes. However, until recently, generating ultrashort and intense pulses from QCLs has been difficult. This would be useful to study ultrafast processes in MIR and THz using the targeted wavelength-by-design properties of QCLs. Since the first demonstration in 2009, mode-locking of QCLs has undergone considerable development in the past decade, which includes revealing the underlying mechanism of pulse formation, the development of an ultrafast THz detection technique, and the invention of novel pulse compression technology, etc. Here, we review the history and recent progress of ultrafast pulse generation from QCLs in both the THz and MIR regimes. [reprint (PDF)]
22.	Impact of scaling base thickness on the performance of heterojunction phototransistors Arash Dehzangi, Abbas Haddadi, Sourav Adhikary, and Manijeh Razeghi Nanotechnology 28, 10LT01-- February 2, 2017 ...[Visit Journal] In this letter we report the effect of vertical scaling on the optical and electrical performance of mid-wavelength infrared heterojunction phototransistors based on type-II InAs/GaSb/AlSb superlattices. The performance of devices with different base thickness was compared as the base was scaled from 60 down to 40 nm. The overall optical performance shows enhancement in responsively, optical gain, and specific detectivity upon scaling the base width. The saturated responsivity for devices with 40 nm bases reaches 8,845 and 9,528 A/W at 77 and 150 K, respectively, which is almost five times greater than devices with 60 nm bases. The saturated optical gain for devices with 40 nm bases is measured as 2,760 at 77 K and 3,081 at 150 K. The devices with 40 nm bases also exhibit remarkable enhancement in saturated current gain, with 17,690 at 77 K, and 19,050 at 150 K. [reprint (PDF)]
22.	Active and passive infrared imager based on short-wave and mid-wave type-II superlattice dual-band detectors E.K. Huang, A. Haddadi, G. Chen, A.M. Hoang, and M. Razeghi Optics Letters, Vol. 38, no. 1, p. 22-24-- January 1, 2013 ...[Visit Journal] A versatile dual-band detector capable of active and passive use is demonstrated using short-wave (SW) and midwave(MW) IR type-II superlattice photodiodes. A bilayer etch-stop scheme is introduced for back-side-illuminated detectors, which enhanced the external quantum efficiency both in the SWIR and MWIR spectral regions. Temperature-dependent dark current measurements of pixel-sized 27 μm detectors found the dark current density to be ~1 × 10^-5 A/cm² for the ∼4.2 μm cutoff MWIR channel at 140 K. This corresponded to a reasonable imager noise equivalent difference in temperature of ∼49 mK using F∕2.3 optics and a 10 ms integration time (t_int), which lowered to ∼13 mK at 110 K using tint 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. Excellent imagery from the dual-band imager exemplifying pixel coincidence is shown. [reprint (PDF)]
22.	High brightness ultraviolet light-emitting diodes grown on patterned silicon substrate Yoann Robin, Kai Ding, Ilkay Demir, Ryan McClintock, Sezai Elagoz, Manijeh Razeghi Materials Science in Semiconductor Processing 90, pp. 87–91-- November 5, 2018 ...[Visit Journal] We report on the fabrication of high brightness AlGaN-based ultraviolet light emitting diodes (UV-LED) on patterned silicon. Using the lateral epitaxial overgrowth approach, we demonstrate the growth of a 6 μm thick AlN layer of high crystalline quality. X-ray diffraction characterization showed a rocking curve with a full width at half maximum of 553 and 768″ for the (00.2) and (10.2) planes, respectively. The low dislocation density of the AlN template enabled the growth of bright AlGaN/ GaN quantum wells emitting at 336 nm. By appropriate flip-chip bonding and silicon substrate removal processing steps, the patterned AlN surface was exposed and efficient bottom-emission UV-LEDs were realized. Improvement of the AlN quality and the structure design allowed the optical output power to reach the milliwatt range under pulsed current, exceeding the previously reported maximum efficiency. Further investigations of the optical power at different pulsed currents and duty cycles show that thermal management in this device structure is still challenging, especially in continuous wave mode operation. The strategy presented here is of interest, since AlN crystalline quality improvement and optimization of the light extraction are the main issues inhibiting efficient UV emitter on silicon fabrication. [reprint (PDF)]
22.	High-brightness LWIR quantum cascade lasers F. Wang, S. Slivken, and M. Razeghi F. Wang, S. Slivken, and M. Razeghi, High-brightness LWIR quantum cascade lasers, Optics Letters, vol. 46, No. 20, 5193 ...[Visit Journal] Long-wave infrared (LWIR, lambda~8-12 um) quantum cascade lasers (QCLs) are drawing increasing interest, as they provide the possibility of long-distance transmission of light through the atmosphere owing to the reduced water absorption. However, their development has been lagging behind the shorter wavelength QCLs due to much bigger technological challenges. In this Letter, through band structure engineering based on a highly localized diagonal laser transition strategy and out-coupler design using an electrically isolated taper structure, we demonstrate high beam quality single-mode LWIR QCLs with high-brightness (2.0 MW cm^-2 sr^-1 for lambda~10 um, 2.2 MW cm^-2 sr^-1 for lambda~9 um, 5.0 MW cm^-2 sr^-1 for lambda~8 um) light extraction from a single facet in continuous-wave operation at 15 ^oC. These results mark an important milestone in exploring the lighting capability of inter-sub-band semiconductor lasers in the LWIR spectral range. [reprint (PDF)]
22.	Self-Detecting Mid-Infrared Dual-Comb Spectroscopy Based on High-Speed Injection-Locked Quantum Cascade Lasers Yu Ma, Dapeng Wu, Ruixin Huang, Shichen Zhang, Binru Zhou, Zejun Ma, Yongqiang Sun, Junqi Liu, Ning Zhuo, Jinchuan Zhang, Shenqiang Zhai, Shuman Liu, Fengqi Liu, Manijeh Razeghi, and Quanyong Lu Ma, Y., Wu, D., Huang, R., Zhang, S., Zhou, B., Ma, Z., Sun, Y., Liu, J., Zhuo, N., Zhang, J., Zhai, S., Liu, S., Liu, F., Razeghi, M. and Lu, Q. (2025), Self-Detecting Mid-Infrared Dual-Comb Spectroscopy Based on High-Speed Injection-Locked Quantum Cascade Lasers. Adv. Photonics Res. 2500062. https://doi.org/10.1002/adpr.202500062 ...[Visit Journal] Dual-comb spectrometer based on quantum cascade lasers (QCLs) is gaining fast development and revolutionizing the precision measurement with high-frequency and temporal resolutions. In these measurements, high-bandwidth photodetectors are normally used for signal acquisition and processing, which complicates the measurement system. QCL is well-known for its picosecond gain-recovery time with an intrinsic bandwidth of tens of GHz. In this work, a compact self-detecting dual-comb spectroscopy (DCS) is demonstrated based on dispersion-engineered, high-speed packaged QCLs under coherent injection locking. The laser source is designed and fabricated into a hybrid-monolithic-integrated waveguide and epi-down packaged on a wideband-designed submount to fully explore the high-speed feature up to fourth-order harmonic state with a cutoff frequency of 40 GHz. The effective radio frequency (RF) injection locking diminishes the issue of optical feedback and enables high-bandwidth self-detection based on QCLs. Clear and stable multiheterodyne signal corresponding to a spectral range of 68 cm−1 and narrow comb tooth linewidth of ≈10 kHz is observed without using external detector or numerical process. The demonstrated broadband, high-power, self-detecting mid-infrared QCL DCS has a great potential for future applications of molecular sensing and spectroscopy. [reprint (PDF)]
21.	AlGaN-based deep-ultraviolet 320 x 256 focal plane array E. Cicek, Z. Vashaei, E.K. Huang, R. McClintock and M. Razeghi OSA Optics Letters, Vol. 37, No. 5, p. 896-898-- March 1, 2012 ...[Visit Journal] We report the synthesis, fabrication, and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, Al_xGa_1−xN–based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al_xGa_1−xN layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower, and falling off three orders of magnitude by ∼285 nm. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows the FPA to achieve high external quantum efficiency (EQE); at 254 nm, average pixels showed unbiased peak responsivity of 75 mA∕W, which corresponds to an EQE of ∼37%. Finally, the uniformity of the FPA and imaging properties are investigated. [reprint (PDF)]
21.	A lifetime of contributions to the world of semiconductors using the Czochralski invention Manijeh Razeghi Journal of Vacuum Volume 146, Pages 308-328-- December 1, 2017 ...[Visit Journal] Over the course of my career, I have made numerous contributions related to semiconductor crystal growth and high performance optoelectronics over a vast region of the electromagnetic spectrum (ultraviolet to terahertz). In 2016 this cumulated in my receiving the Jan Czochralski Gold Medal award from the European Materials Research Society. This article is designed to provide a historical perspective and general overview of these scientific achievements, on the occasion of being honored by this award. These achievements would not have been possible without high quality crystalline substrates, and this article is written in honor of Jan Czochralski on the 100th anniversary of his important discovery. [reprint (PDF)]
21.	Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output Q. Y. Lu, S. Manna, S. Slivken, D. H. Wu, and M. Razeghi AIP Advances 7, 045313 -- April 26, 2017 ...[Visit Journal] Chromatic dispersion control plays an underlying role in optoelectronics and spectroscopy owing to its enhancement to nonlinear interactions by reducing the phase mismatching. This is particularly important to optical frequency combs based on quantum cascade lasers which require negligible dispersions for efficient mode locking of the dispersed modes into equally spaced comb modes. Here, we demonstrated a dispersion compensated mid-IR quantum cascade laser frequency comb with high power output at room temperature. A low-loss dispersive mirror has been engineered to compensate the device’s dispersion residue for frequency comb generation. Narrow intermode beating linewidths of 40 Hz in the comb-working currents were identified with a high power output of 460 mW and a broad spectral coverage of 80 cm^-1. This dispersion compensation technique will enable fast spectroscopy and high-resolution metrology based on QCL combs with controlled dispersion and suppressed noise. [reprint (PDF)]
20.	Nanoselective area growth of defect-free thick indium-rich InGaN nanostructures on sacriﬁcial ZnO templates Renaud Puybaret, David J Rogers, Youssef El Gmili, Suresh Sundaram, Matthew B Jordan, Xin Li, Gilles Patriarche, Ferechteh H Teherani, Eric V Sandana, Philippe Bove, Paul L Voss, Ryan McClintock, Manijeh Razeghi, Ian Ferguson, Jean-Paul Salvestrini, and Abdallah Ougazzade Nanotechnology 28 195304-- April 29, 2017 ...[Visit Journal] Nanoselective area growth (NSAG) by metal organic vapor phase epitaxy of high-quality InGaN nanopyramids on GaN-coated ZnO/c-sapphire is reported. Nanopyramids grown on epitaxial low-temperature GaN-on-ZnO are uniform and appear to be single crystalline, as well as free of dislocations and V-pits. They are also indium-rich (with homogeneous 22% indium incorporation) and relatively thick (100 nm). These properties make them comparable to nanostructures grown on GaN and AlN/Si templates, in terms of crystallinity, quality, morphology, chemical composition and thickness. Moreover, the ability to selectively etch away the ZnO allows for the potential lift-off and transfer of the InGaN/GaN nanopyramids onto alternative substrates, e.g. cheaper and/or ﬂexible. This technology offers an attractive alternative to NSAG on AlN/Si as a platform for the fabrication of high quality, thick and indium-rich InGaN monocrystals suitable for cheap, ﬂexible and tunable light-emitting diodes. [reprint (PDF)]
20.	High Power Quantum Cascade Lasers (QCLs) Grown by GasMBE M. Razeghi and S. Slivken SPIE Proceedings, International Conference on Solid State Crystals (ICSSC), Zakopane, Poland, -- October 14, 2002 ...[Visit Journal] This paper is a brief summary of the technological development and state-of-the-art performance of quantum cascade lasers produced at the Centre for Quantum Devices. Laser design will be discussed, as well as experimental details of device fabrication. Recent work has focused on the development of high peak and average power QCLs emitting at room temperature and above. Scaling of the output is demonstrated by increasing the number of emitting regions in the waveguide core. At λ = 9 µm, over 7 W of peak power has been demonstrated at room temperature for a single diode, with an average power of 300 mW at 6% duty cycle. At shorter wavelengths, laser development includes the use of highly strain-balanced heterostructures in order to maintain a high conduction band offset and minimize leakage current. At λ = 6 µm, utilizing a high reflective coating and epilayer-down mounting of the laser, we have demonstrated 225 mW of average power from a single facet at room temperature. Lastly, these results are put in perspective of other reported results and possible future directions are discussed. [reprint (PDF)]
20.	Recent advances of terahertz quantum cascade lasers Manijeh Razeghi Proc. SPIE 8119, Terahertz Emitters, Receivers, and Applications II, 81190D (September 07, 2011)-- November 7, 2011 ...[Visit Journal] In the past decade, tremendous development has been made in GaAs/AlGaAs based THz quantum cascade laser (QCLs), however, the maximum operating temperature is still limited below 200 K (without magnetic field). THz QCL based on difference frequency generation (DFG) represents a viable technology for room temperature operation. Recently, we have demonstrated room temperature THz emission (∼ 4 THz) up to 8.5 μW with a power conversion efficiency of 10 μW/W². A dual-period distributed feedback grating is used to filter the mid-infrared spectra in favor of an extremely narrow THz linewidth of 6.6 GHz. [reprint (PDF)]
19.	High performance InAs quantum dot infrared photodetectors (QDIP) on InP by MOCVD W. Zhang, H. Lim, M. Taguchi, S. Tsao, J. Szafraniec, B. Movaghar, M. Razeghi, and M. Tidrow SPIE Conference, Jose, CA, Vol. 5732, pp. 326-- January 22, 2005 ...[Visit Journal] Inter-subband detectors such as quantum well infrared photodetectors (QWIP) have been widely used in infrared detection. Quantum dot infrared photodetectors (QDIPs) have been predicted to have better performance than QWIPs including higher operation temperature and normal incidence detection. Here we report our recent results of InAs QDIP grown on InP substrate by low-pressure metalorganic chemical vapor deposition (MOCVD). The device structures consist of multiple stacks of InAs quantum dots with InP barriers. High detectivities in the range of 10¹⁰cm·Hz^1/2/W were obtained at 77K. The measurements at higher temperatures show better temperature dependent performance than QWIP. However, the performances of QDIPs are still far from the expected. One of the reasons is the low quantum efficiency due to the low fill factor of quantum dots layer. Resonant cavity enhanced QDIP has been studied to increase the quantum efficiency. Different schemes of mirrors using free carrier plasma and distributed Bragg reflector are discussed. [reprint (PDF)]
19.	Multiple-band, Single-mode, High-power, Phase-locked, Mid-infrared Quantum Cascade Laser Arrays Manijeh Razeghi, Wenjia Zhou, Quanyong Lu, Donghai Wu, and Steven Slivken Imaging and Applied Optics 2018, JTh1A.2-- September 15, 2018 ...[Visit Journal] Single-mode, 16-channel, phase-locked laser arrays based on quantum cascade laser technology are demonstrated at multiple spectral bands across the mid-infrared spectrum region. High peak output power of 50W is achieved around the long-wavelength band of 7.7µm, while a side mode suppression ratio over 25dB is obtained. Far field distribution measurement result indicates a uniform phase distribution across the array output. [reprint (PDF)]

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