Center for Quantum Devices - Most Downloaded Journal Articles

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16.	Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers Manijeh. Razeghi, Abbas Haddadi, Arash Dehzangi, Romain Chevallier, and Thomas Yang Proceedings of SPIE 10177, Infrared Technology and Applications XLIII, 1017705-- May 9, 2017 ...[Visit Journal] InAs/InAs_1-xSb_x/AlAs_1-xSb_x type-II superlattices (T2SLs) is a system of multi-interacting quantum wells. Since its introduction, this material system has drawn a lot of attention especially for infrared detection. In recent years, InAs/InAs_1- xSb_x/AlAs_1-xSb_x T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photodetectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). In this paper, we will present the current status of InAs/InAs_1-xSb_x/AlAs_1-xSb_x T2SL-based photodetectors for detection in different infrared regions, from short-wavelength (SWIR) to long-wavelength (LWIR) infrared, and the future outlook of this material system. [reprint (PDF)]
16.	Use of ZnO thin films as sacrifical templates for metal organic vapor phase epitaxy and chemical lift-off of GaN D.J. Rogers, F. Hosseini Teherani, A. Ougazzaden, S. Gautier, L. Divay, A. Lusson, O. Durand, F. Wyczisk, G. Garry, T. Monteiro, M.R. Correira, M. Peres, A. Neves, D. McGrouther, J.N. Chapman, and M. Razeghi Applied Physics Letters, Vol. 91, No. 7, p. 071120-1-- August 13, 2007 ...[Visit Journal] Continued development of GaN-based light emitting diodes is being hampered by constraints imposed by current non-native substrates. ZnO is a promising alternative substrate but it decomposes under the conditions used in conventional GaN metal organic vapor phase epitaxy (MOVPE). In this work, GaN was grown on ZnO/c-Al₂O₃ using low temperature/pressure MOVPE with N₂ as a carrier and dimethylhydrazine as a N source. Characterization confirmed the epitaxial growth of GaN. The GaN was lifted-off the c-Al₂O₃ by chemically etching away the ZnO underlayer. This approach opens up the way for bonding of the GaN onto a support of choice. [reprint (PDF)]
16.	Quantum cascade lasers: from tool to product M. Razeghi, Q. Y. Lu, N. Bandyopadhyay, W. Zhou, D. Heydari, Y. Bai, and S. Slivken Optics Express Vol. 23, Issue 7, pp. 8462-8475-- March 25, 2015 ...[Visit Journal] The quantum cascade laser (QCL) is an important laser source in the mid-infrared and terahertz frequency range. The past twenty years have witnessed its tremendous development in power, wall plug efficiency, frequency coverage and tunability, beam quality, as well as various applications based on QCL technology. Nowadays, QCLs can deliver high continuous wave power output up to 5.1 W at room temperature, and cover a wide frequency range from 3 to 300 μm by simply varying the material components. Broadband heterogeneous QCLs with a broad spectral range from 3 to 12 μm, wavelength agile QCLs based on monolithic sampled grating design, and on-chip beam QCL combiner are being developed for the next generation tunable mid-infrared source for spectroscopy and sensing. Terahertz sources based on nonlinear generation in QCLs further extend the accessible wavelength into the terahertz range. Room temperature continuous wave operation, high terahertz power up to 1.9 mW, and wide frequency tunability form 1 to 5 THz makes this type of device suitable for many applications in terahertz spectroscopy, imaging, and communication. [reprint (PDF)]
16.	Demonstration of InAsSb/AlInSb Double Heterostructure Detectors for Room Temperature Operation in the 5–8 μm Wavelength Range J.S. Wojkowski, H. Mohseni, J.D. Kim, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] We report the first demonstration of InAsSb/AlInSb double heterostructure detectors for room temperature operation. The structures were grown in a solid source molecular beam epitaxy reactor on semi-insulating GaAs substrate. The material was processed to 400x400 micrometer mesas using standard photolithography, etching, and metallization techniques. No optical immersion or surface passivation was used. The photovoltaic detectors showed a cutoff wavelength at 8 micrometer at 300 K. The devices showed a high quantum efficiency of 40% at 7 μm at room temperature. A responsivity of 300 mA/W was measured at 7 μm under a reverse bias of 0.25 V at 300 K resulting in a Johnson noise limited detectivity of 2x10⁸ cm·Hz^½/W. [reprint (PDF)]
16.	Focal plane arrays based on quantum dot infrared photodetectors Manijeh Razeghi; Wei Zhang; Ho-Chul Lim; Stanley Tsao; John Szafraniec; Maho Taguchi; Bijan Movaghar Proc. SPIE 5838, Nanotechnology II, 125 (June 28, 2005);-- June 28, 2005 ...[Visit Journal] Here we report the first demonstrations of infrared focal plane array (FPA) based on GaAs and InP based quantum dot infrared photodetectors (QDIPs). QDIPs are extension of quantum well infrared photodetectors (QWIPs) and are predicted to outperform QWIPs due to their potential advantages including normally incident absorption, higher responsivity and high temperature operation. Two material systems have been studied: InGaAs/InGaP QDIPs on GaAs substrates and InAs QDIP on InP substrates. An InGaAs/InGaP QDIP has been grown on GaAs substrate by LP-MOCVD. Photoresponse was observed at temperatures up to 200 K with a peak wavelength of 4.7 μm and cutoff wavelength of 5.2 μm. A detectivity of 1.2x10¹¹ cm·Hz^1/2/W was obtained at T=77 K and bias of -0.9 V, which is the highest for QDIPs grown by MOCVD. An InAs QDIP structure has also been grown on InP substrate by LP-MOCVD. Photoresponse of normal incidence was observed at temperature up to 160K with a peak wavelength of 6.4 μm and cutoff wavelength of 6.6 μm. A detectivity of 1.0x10¹⁰ cm·Hz^1/2/W was obtained at 77K at biases of -1.1 V, which is the first and highest detectivity reported for QDIP on InP substrate. 256×256 detector arrays were fabricated first time in the world for both the GaAs and InP based QDIPs. Dry etching and indium bump bonding were used to hybridize the arrays to a Litton readout integrated circuit. For the InGaAs/InGaP QDIP FPA, thermal imaging was achieved at temperatures up to 120 K. At T=77K, the noise equivalent temperature difference (NEDT) was measured as 0.509K with a 300K background and f/2.3 optics. For the InP based QDIPs, thermal imaging was achieved at 77 K. [reprint (PDF)]
16.	Monolithic terahertz source Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi Nature Photonics \| Research Highlights -- July 31, 2014 ...[Visit Journal] To date, the production of continuous-wave terahertz (THz) sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers operating at room temperature has proved elusive. A critical problem is that, to achieve a large nonlinear susceptibility for frequency conversion, the active region of the quantum cascade laser requires high doping, which elevates the lasing threshold current density. Now, Quan-Yong Lu and colleagues from Northwestern University in the USA have overcome this problem and demonstrated a room-temperature continuous-wave THz source based on difference-frequency generation in quantum cascade lasers. They designed quantum-well structures based on In_0.53Ga_0.47As/In_0.52Al_0.48As material system for two mid-infrared wavelengths. The average doping in the active region was about 2.5 × 10¹⁶ cm⁻³. A buried ridge, buried composite distributed-feedback waveguide with the Čerenkov phase-matching scheme was used to reduce the waveguide loss and enhance heat dissipation. As a result, single-mode emission at 3.6 THz was observed at 293 K. The continuous-wave THz power reached 3 μW with a conversion efficiency of 0.44 mW W⁻² from mid-infrared to THz waves. Using a similar device design, a THz peak power of 1.4 mW was achieved in pulse mode. [reprint (PDF)]
16.	Room temperature neagtive differential resistance characteristics of polar III-nitride resonant tunneling diodes C. Bayram, Z. Vashaei, and M. Razeghi Applied Physics Letters, Vol. 97, No. 9, p. 092104-1-- August 30, 2010 ...[Visit Journal] III-nitride resonant tunneling diodes (RTDs), consisting Al_0.2Ga_0.8N/GaN double-barrier (DB) active layers, were grown on c-plane lateral epitaxial overgrowth (LEO) GaN/sapphire and c-plane freestanding (FS) GaN. RTDs on both templates, fabricated into mesa diameters ranging from 5 to 35 μm, showed negative differential resistance (NDR) at room temperature. NDR characteristics (voltage and current density at NDR onset and current-peak-to-valley ratio) were analyzed and reported as a function of device size and substrate choice. Our results show that LEO RTDs perform as well as FS ones and DB active layer design and quality have been the bottlenecks in III-nitride RTDs. [reprint (PDF)]
16.	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)]
16.	Sb-based infrared materials and photodetectors for the 3-5 and 8-12 μm range E. Michel, J.D. Kim, S. Park, J. Xu, I. Ferguson, and M. Razeghi SPIE Photonics West '96 'Photodetectors: Materials and Devices'; Proceedings 2685-- January 27, 1996 ...[Visit Journal] In this paper, we report on the growth of InSb on (100) Si and (111)B GaAs substrates and the growth of InAsSb alloys for longer wavelength applications. The fabrication and characterization of photodetectors based on these materials are also reported. Both photoconductive and photovoltaic devices are investigated. The photodiodes are InSb p-i-n structures and InSb/InAs_1-xSb_x/InSb double heterostructures grown on (100) and (111)B semi-insulating GaAs and Si substrates by low pressure metalorganic chemical vapor deposition and solid source molecular beam epitaxy. The material parameters for device structures have been optimized through theoretical calculations based on fundamental mechanisms. InSb p-i-n photodiodes with 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 R₀A product of InAsSb detectors has been theoretically and experimentally analyzed. [reprint (PDF)]
16.	Novel process for direct bonding of GaN onto glass substrates using sacrificial ZnO template layers to chemically lift-off GaN from c-sapphire Rogers, D. J.; Ougazzaden, A.; Sandana, V. E.; Moudakir, T.; Ahaitouf, A.; Teherani, F. Hosseini; Gautier, S.; Goubert, L.; Davidson, I. A.; Prior, K. A.; McClintock, R. P.; Bove, P.; Drouhin, H.-J.; Razeghi, M. Proc. SPIE 8263, Oxide-based Materials and Devices III, 82630R (February 9, 2012)-- February 9, 2012 ...[Visit Journal] GaN was grown on ZnO-buffered c-sapphire (c-Al₂O₃) substrates by Metal Organic Vapor Phase Epitaxy. The ZnO then served as a sacrificial release layer, allowing chemical lift-off of the GaN from the c-Al₂O₃ substrate via selective wet etching of the ZnO. The GaN was subsequently direct-wafer-bonded onto a glass substrate. X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray microanalysis, Room Temperature Photoluminescence & optical microscopy confirmed bonding of several mm2 of crack-free wurtzite GaN films onto a soda lime glass microscope slide with no obvious deterioration of the GaN morphology. Using such an approach, InGaN based devices can be lifted-off expensive single crystal substrates and bonded onto supports with a better cost-performance profile. Moreover, the approach offers the possibility of reclaiming and reusing the substrate. [reprint (PDF)]
16.	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)]
16.	Thermal characteristics and analysis of quantum cascade lasers for biochemical sensing applications J.S. Yu, H.K. Lee, S. Slivken, and M. Razeghi SPIE Proceedings, Biosensing II, San Diego, CA (August 2-6, 2009), Vol. 7397, p. 739705-1-- August 2, 2009 ...[Visit Journal] We studied the thermal characteristics and analysis of InGaAs/InAlAs quantum cascade lasers (QCLs) in terms of internal temperature distribution, heat flux, and thermal conductance from the heat transfer simulation. The heat source densities were obtained from threshold power densities measured experimentally for QCLs under room-temperature continuous-wave operation. The use of a thick electroplated Au around the laser ridges helps increase the heat removal from devices. The two-dimensional anisotropic heat dissipation model was used to analyze the thermal behaviors inside the device. The simulation results were also compared with those estimated from experimental data. [reprint (PDF)]
16.	Room temperature compact THz sources based on quantum cascade laser technology M. Razeghi; Q.Y. Lu; N. Bandyopadhyay; S. Slivken; Y. Bai Proc. SPIE 8846, Terahertz Emitters, Receivers, and Applications IV, 884602 (September 24, 2013)-- November 24, 2013 ...[Visit Journal] We present the high performance THz sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers. Room temperature single-mode operation in a wide THz spectral range of 1-4.6 THz is demonstrated from our Čerenkov phase-matched THz sources with dual-period DFB gratings. High THz power up to 215 μW at 3.5 THz is demonstrated via epi-down mounting of our THz device. The rapid development renders this type of THz sources promising local oscillators for many astronomical and medical applications. [reprint (PDF)]
16.	Angled cavity broad area quantum cascade lasers Y. Bai, S. Slivken, Q.Y. Lu, N. Bandyopadhyay, and M. Razeghi Applied Physics Letters, Vol. 100, Np. 8, p. 081106-1-- August 20, 2012 ...[Visit Journal] Angled cavity broad area quantum cascade lasers (QCLs) are investigated with surface gratingbased distributed feedback (DFB) mechanisms. It is found that an angled cavity incorporating a one dimensional DFB with grating lines parallel to the laser facet offers the simplest solution for single mode and diffraction limited emission in the facet normal direction. A room temperature single mode QCL with the highest output power for wavelengths longer than 10 micron is demonstrated. This structure could be applied to a wide range of laser structures for power scaling along with spectral and spatial beam control. [reprint (PDF)]
16.	Structural, Optical, Electrical and Morphological Study of Transparent p-NiO/n-ZnO Heterojunctions Grown by PLD V. E. Sandana, D. J. Rogers, F. Hosseini Teherani, P. Bove, N. Ben Sedrine, M. R. Correia, T. Monteiro, R. McClintock, and M. Razeghi Proc. SPIE 9364, Oxide-based Materials and Devices VI, 93641O-- March 24, 2015 ...[Visit Journal] NiO/ZnO heterostructures were fabricated on FTO/glass and bulk hydrothermal ZnO substrates by pulsed laser deposition. X-Ray diffraction and Room Temperature (RT) Raman studies were consistent with the formation of (0002) oriented wurtzite ZnO and (111) oriented fcc NiO. RT optical transmission studies revealed bandgap energy values of ~3.70 eV and ~3.30 eV for NiO and ZnO, respectively and more than 80% transmission for the whole ZnO/NiO/FTO/glass stack over the majority of the visible spectrum. Lateral p-n heterojunction mesas (~6mm x 6mm) were fabricated using a shadow mask during PLD growth. n-n and p-p measurements showed that Ti/Au contacting gave an Ohmic reponse for the NiO, ZnO and FTO. Both heterojunctions had rectifying I/V characteristics. The junction on FTO/glass gave forward bias currents (243mA at +10V) that were over 5 orders of magnitude higher than those for the junction formed on bulk ZnO. At ~ 10^-7 A (for 10V of reverse bias) the heterojunction leakage current was approximately two orders of magnitude lower on the bulk ZnO substrate than on FTO. Overall, the lateral p-NiO/n-ZnO/FTO/glass device proved far superior to that formed by growing p-NiO directly on the bulk n-ZnO substrate and gave a combination of electrical performance and visible wavelength transparency that could predispose it for use in various third generation transparent electronics applications. [reprint (PDF)]
15.	Long-term reliability of Al-free InGaAsP/GaAs λ = 808 nm) lasers at high-power high-temperature operation J. Diaz, H. Yi, M. Razeghi and G.T. Burnham Applied Physics Letters 71 (21)-- November 24, 1997 ...[Visit Journal] We report the long-term reliability measurement on uncoated Al-free InGaAsP/GaAs (λ = 808 nm) lasers at high-power and high-temperature operation. No degradation in laser performance has been observed for over 30 ,000 h of lifetime testing in any of randomly selected several 100 μm-wide uncoated lasers operated at 60 °C with 1 W continuous wave output power. This is the first and the most conclusive evidence ever reported that directly shows the high long-term reliability of uncoated Al-free lasers. [reprint (PDF)]
15.	Intrinsic AlGaN photodetectors for the entire compositional range D. Walker, X. Zhang, A. Saxler, P. Kung, J. Xu, and M. Razeghi SPIE Conference, San Jose, CA, -- February 12, 1997 ...[Visit Journal] Al_xGa_1-xN ultraviolet photoconductors with cut- off wavelengths from 365 nm to 200 nm have been fabricated and characterized. Various characteristics of the devices, such as photoresponse, voltage-dependent responsivity, frequency-dependent responsivity and noise spectral density, were measured and cross-referenced with optical, electrical and structural characteristics of the material to provide information about the mechanisms taking place during detection. The maximum detectivity reached 5.5 X 10⁸ cm·Hz^½/W at a modulating frequency of 14 Hz. The effective majority carrier lifetime in Al_xGa_1-xN materials, derived from frequency-dependent photoconductivity measurements, has been estimated to be from 6 to 35 msec. The frequency-dependent noise-spectrum shows that it is dominated by Johnson-noise at high frequencies for low Al-composition samples. [reprint (PDF)]
15.	Low irradiance background limited type-II superlattice MWIR M-barrier imager E.K. Huang, S. Abdollahi Pour, M.A. Hoang, A. Haddadi, M. Razeghi and M.Z. Tidrow OSA Optics Letters (OL), Vol. 37, No. 11, p. 2025-2027-- June 1, 2012 ...[Visit Journal] We report a type-II superlattice mid-wave infrared 320 × 256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ∼99%operability. The 280 K blackbody’s photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ∼5 × 10¹² ph·cm⁻²·s⁻¹. Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ∼5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ∼5 × 10¹⁰ ph·cm⁻²·s⁻¹ and temperature sensitivity of 9 mK with F∕2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array’s uniform responsivity. [reprint (PDF)]
15.	Infrared Imaging Arrays Using Advanced III-V Materials and technology M. Razeghi, J.D. Kim, C. Jelen, S. Slivken, E. Michel, H. Mohseni, J.J. Lee, J. Wojkowski, K.S. Kim, H.I. Jeon, and J. X IEEE Proceedings, Advanced Workshop on Frontiers in Electronics (WOFE), Tenerife, Spain;-- January 6, 1997 ...[Visit Journal] Photodetectors operating in the 3-5 and 8-12 μm atmospheric windows are of great importance for applications in infrared (IR) thermal imaging. HgCdTe has been the dominant material system for these applications. However, it suffers from instability and non-uniformity problems over large areas due to high Hg vapor pressure during the material, growth. There has been a lot of interest in the use of heteroepitaxially grown Sb-based alloys, its strained layer superlattices, and GaAs based quantum wells as alternatives to MCT. This interest has been driven by the advanced material growth and processing technology available for the III-V material system [reprint (PDF)]
15.	Self-assembled semiconductor quantum dot infrared photodetector operating at room temperature and focal plane array Ho-Chul Lim; Stanley Tsao; Wei Zhang; Manijen Razeghi Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 65420R (May 14, 2007)-- May 14, 2007 ...[Visit Journal] Self-assembled semiconductor quantum dots have attracted much attention because of their novel properties and thus possible practical applications including the lasers, detectors and modulators. Especially the photodetectors which have quantum dots in their active region have been developed and show promising performances such as high operation temperature due to three dimensional confinement of the carriers and normal incidence in contrast to the case of quantum well detectors which require special optical coupling schemes. Here we report our recent results for mid-wavelength infrared quantum dot infrared photodetector grown by low-pressure metalorganic chemical vapor deposition. The material system we have investigated consists of 25 period self-assembled InAs quantum dot layers on InAlAs barriers, which are lattice-matched to InP substrates, covered with InGaAs quantum well layers and InAlAs barriers. This active region was sandwiched by highly doped InP contact layers. The device operates at 4.1 μm with a peak detectivity of 2.8×10¹¹ cm·Hz^1/2/W at 120 K and a quantum efficiency of 35 %. The photoresponse can be observed even at room temperature resulting in a peak detectivity of 6×10⁷ cm·Hz^1/2/W. A 320×256 focal plane array has been fabricated in this kind of device. Its performance will also be discussed here. [reprint (PDF)]
15.	High Power Mid-Infrared Quantum Cascade Lasers Grown on GaAs Steven Slivken and Manijeh Razeghi Photonics 2022, 9(4), 231 (COVER ARTICLE) ...[Visit Journal] The motivation behind this work is to show that InP-based intersubband lasers with high power can be realized on substrates with significant lattice mismatch. This is a primary concern for the integration of mid-infrared active optoelectronic devices on low-cost photonic platforms, such as Si. As evidence, an InP-based mid-infrared quantum cascade laser structure was grown on a GaAs substrate, which has a large (4%) lattice mismatch with respect to InP. Prior to laser core growth, a metamorphic buffer layer of InP was grown directly on a GaAs substrate to adjust the lattice constant. Wafer characterization data are given to establish general material characteristics. A simple fabrication procedure leads to lasers with high peak power (>14 W) at room temperature. These results are extremely promising for direct quantum cascade laser growth on Si substrates. [reprint (PDF)]
15.	The importance of band alignment in VLWIR type-II InAs/GaSb heterodiodes containing the M-structure barrier D. Hoffman, B.M. Nguyen, E.K. Huang, P.Y. Delaunay, S. Bogdanov, P. Manukar, M. Razeghi, and V. Nathan SPIE Proceedings, San Jose, CA Volume 7222-15-- January 26, 2009 ...[Visit Journal] The Type-II InAs/GaSb superlattice photon detector is an attractive alternative to HgCdTe photodiodes and QWIPS. The use of p+ - pi - M - N+ heterodiode allows for greater flexibility in enhancing the device performance. The utilization of the Empirical Tight Binding method gives the band structure of the InAs/GaSb superlattice and the new M- structure (InAs/GaSb/AlSb/GaSb) superlattice allowing for the band alignment between the binary superlattice and the M- superlattice to be determined and see how it affects the optical performance. Then by modifying the doping level of the M- superlattice an optimal level can be determined to achieve high detectivity, by simultaneously improving both photo-response and reducing dark current for devices with cutoffs greater than 14.5 µm. [reprint (PDF)]
15.	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)]
15.	Growth of “moth-eye” ZnO nanostructures on Si(111), c-Al2O3, ZnO and steel substrates by pulsed laser deposition Vinod E. Sandana, David J. Rogers, Ferechteh Hosseini Teherani, Philippe Bove, Michael Molinari, Michel Troyon, Alain Largeteau, Gérard Demazeau, Colin Scott, Gaelle Orsal, Henri-Jean Drouhin, Abdallah Ougazzaden, Manijeh Razeghi Phys. Status Solidi C., 1-5 (2013)-- August 6, 2013 ...[Visit Journal] Self-forming, vertically-aligned, arrays of black-body-like ZnO moth-eye nanostructures were grown on Si(111), c-Al₂O₃, ZnO and high manganese austenitic steel substrates using Pulsed Laser Deposition. X-ray diffraction (XRD) revealed the nanostructures to be well-crystallised wurtzite ZnO with strong preferential c-axis crystallographic orientation along the growth direction for all the substrates. Cathodoluminescence (CL) studies revealed emission characteristic of the ZnO near band edge for all substrates. Such moth-eye nanostructures have a graded effective refractive index and exhibit black-body characteristics. Coatings with these features may offer improvements in photovoltaic and LED performance. Moreover, since ZnO nanostructures can be grown readily on a wide range of substrates it is suggested that such an approach could facilitate growth of GaN-based devices on mismatched and/or technologically important substrates, which may have been inaccessible till present. [reprint (PDF)]
15.	Negative luminescence of InAs/GaSb superlattice photodiodes F. Fuchs, D. Hoffman, A. Gin, A. Hood, Y. Wei, and M. Razeghi Phys. Stat. Sol. C 3 (3)-- February 22, 2006 ...[Visit Journal] The emission behaviour of InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 µm and 13 μm. With a radiometric calibration of the experimental set-up the internal quantum efficiency has been determined in the temperature range between 80 K and 300 K for both, the negative and positive luminescence. The quantitative analysis of the internal quantum efficiency of the non-equilibrium radiation enables the determination of the Auger coefficient. [reprint (PDF)]

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