Center for Quantum Devices - Most Downloaded Journal Articles

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2.	Quantum-Cascade Lasers Operating in Continuous-Wave Mode Above 90°C at λ ~5.25 µm A. Evans, J. Nguyen, S. Slivken, J.S. Yu, S.R. Darvish, and M. Razeghi Applied Physics Letters 88 (5)-- January 30, 2006 ...[Visit Journal] We report on the design and fabrication of λ~5.25 μm quantum-cascade lasers (QCLs) for very high temperature continuous-wave (CW) operation. CW operation is reported up to a maximum temperature of 90 °C (363 K). CW output power is reported in excess of 500 mW near room temperature with a low threshold current density. A finite element thermal model is used to investigate the G_th and maximum CW operating temperature of the QCLs. [reprint (PDF)]
2.	High power broad area quantum cascade lasers Y. Bai, S. Slivken, S.R. Darvish, A. Haddadi, B. Gokden and M. Razeghi Applied Physics Letters, Vol. 95, No. 22, p. 221104-1-- November 30, 2009 ...[Visit Journal] Broad area quantum cascade lasers (QCLs) are studied with ridge widths up to 400 µm, in room temperature pulsed mode operation at an emission wavelength around 4.45 µm. The peak output power scales linearly with the ridge width. A maximum total peak output power of 120 W is obtained from a single 400-µm-wide device with a cavity length of 3 mm. A stable far field emission characteristic is observed with dual lobes at ±38° for all tested devices, which suggests that these broad area QCLs are highly resistant to filamentation. [reprint (PDF)]
2.	High-power, continuous-wave, phase-locked quantum cascade laser arrays emitting at 8 μm WENJIA ZHOU,QUAN-YONG LU,DONG-HAI WU, STEVEN SLIVKEN, AND MANIJEH RAZEGHI OPTICS EXPRESS 27, 15776-15785-- May 20, 2019 ...[Visit Journal] We report a room-temperature eight-element phase-locked quantum cascade laser array emitting at 8 μm with a high continuous-wave power of 8.2 W and wall plug efficiency of 9.5%. The laser array operates primarily via the in-phase supermode and has single-mode emission with a side-mode suppression ratio of ~20 dB. The quantum cascade laser active region is based on a high differential gain (8.7 cm/kA) and low voltage defect (90 meV) design. A record high wall plug efficiency of 20.4% is achieved from a low loss buried ridge type single-element Fabry-Perot laser operating in pulsed mode at 20 °C. [reprint (PDF)]
2.	InSb Infrared Photodetectors on Si Substrates Grown by Molecular Beam Epitaxy E. Michel, J. Xu, J.D. Kim, I. Ferguson, and M. Razeghi IEEE Photonics Technology Letters 8 (5) pp. 673-- May 1, 1996 ...[Visit Journal] The InSb infrared photodetectors grown heteroepitaxially on Si substrates by molecular beam epitaxy (MBE) are reported. Excellent InSb material quality is obtained on 3-in Si substrates (with a GaAs predeposition) as confirmed by structural, optical, and electrical analysis. InSb infrared photodetectors on Si substrates that can operate from 77 K to room temperature have been demonstrated. The peak voltage-responsitivity at 4 μm is about 1.0×10³ V/W and the corresponding Johnson-noise-limited detectivity is calculated to be 2.8×10¹⁰ cm·Hz^½/W. This is the first important stage in developing InSb detector arrays or monolithic focal plane arrays (FPAs) on silicon. The development of this technology could provide a challenge to traditional hybrid FPA's in the future. [reprint (PDF)]
2.	Stability of far fields in double heterostructure and multiple quantum well InAsSb/InPAsSb/InAs midinfrared lasers H. Yi, A. Rybaltowski, J. Diaz, D. Wu, B. Lane, Y. Xiao, and M. Razeghi Applied Physics Letters 70 (24)-- June 16, 1997 ...[Visit Journal] Far fields in perpendicular direction to the junction are investigated in double heterostructure (DH) and multiple quantum well (MQW) midwave-infrared InAsSb/InPAsSb/InAs lasers (λ = 3.2–3.6 μm). Strong broadening of the far fields in the DH lasers was observed with increases in temperature and/or current. On the contrary, MQW lasers with otherwise identical structure exhibit very stable far fields as narrow as 23° for all the operating conditions investigated. Our experiment and theoretical modeling suggest that these different behaviors of far fields in DH and MQW lasers are attributed to the refractive index fluctuation in the InAsSb laser active region. [reprint (PDF)]
2.	High Temperature Continuous Wave Operation of ~8 μm Quantum Cascade Lasers S. Slivken, A. Matlis, C. Jelen, A. Rybaltowski, J. Diaz, and M. Razeghi Applied Physics Letters 74 (2)-- January 11, 1999 ...[Visit Journal] We report single-mode continuous-wave operation of a λ∼8 μm quantum cascade laser at 140 K. The threshold current density is 4.2 kA/cm² at 300 K in pulsed mode and 2.5 kA/cm² at 140 K in continuous wave for 2 mm long index-guided laser cavities of 20 μm width. Wide stripe (W ∼ 100 μm), index-guided lasers from the same wafer in pulsed operation demonstrate an average T₀ of 210 K with other wafers demonstrating a T₀ as high as 290 K for temperatures from 80 to 300 K. This improvement in high-temperature performance is a direct result of three factors: excellent material quality, a low-loss waveguide design, and a low-leakage index-guided laser geometry. [reprint (PDF)]
2.	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)]
2.	A review of the growth, doping, and applications of β-Ga₂O₃ thin films Manijeh Razeghi, Ji-Hyeon Park , Ryan McClintock, Dimitris Pavlidis, Ferechteh H. Teherani, David J. Rogers, Brenden A. Magill, Giti A. Khodaparast, Yaobin Xu, Jinsong Wu, Vinayak P. Dravid Proc. SPIE 10533, Oxide-based Materials and Devices IX, 105330R -- March 14, 2018 ...[Visit Journal] β-Ga₂O₃ is emerging as an interesting wide band gap semiconductor for solar blind photo detectors (SBPD) and high power field effect transistors (FET) because of its outstanding material properties including an extremely wide bandgap (Eg ~4.9eV) and a high breakdown field (8 MV/cm). This review summarizes recent trends and progress in the growth/doping of β-Ga₂O₃ thin films and then offers an overview of the state-of-the-art in SBPD and FET devices. The present challenges for β-Ga₂O₃ devices to penetrate the market in real-world applications are also considered, along with paths for future work. [reprint (PDF)]
2.	Room temperature terahertz quantum cascade laser sources with 215 μW output power through epilayer-down mounting Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai, and M. Razeghi Appl. Phys. Lett. 103, 011101 (2013)-- July 1, 2013 ...[Visit Journal] We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215 μW are obtained, respectively. [reprint (PDF)]
2.	High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs_1-xSb_x superlattice photodetector by MOCVD Donghai Wu, Arash Dehzangi, Jiakai Li, and Manijeh Razeghi Appl. Phys. Lett. 116, 161108-- April 21, 2020 ...[Visit Journal] We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs_1-xSb_x superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77K, the photodetector exhibits a peak responsivity of 0.70A/W at 3.65λ, corresponding to a quantum efﬁciency of 24% at zero bias without anti-reﬂection coating, with a 50% cutoff wavelength of 4.28λ. With an R₀A value of 3.2x10⁵ Ω·cm² and a dark current density of 9.6x10^-8 A/cm² bias of -20mV at 77K, the photodetector exhibits a speciﬁc detectivity of 2.9x10¹²cm·Hz^½/W. At 150K, the photodetector exhibits a dark current density of 9.1x10^-6 A/cm² and a quantum efﬁciency of 25%, resulting in a detectivity of 3.4x10¹¹cm·Hz/W. [reprint (PDF)]
2.	High-quality MOCVD-grown heteroepitaxial gallium oxide growth on III-nitrides enabled by AlOx interlayer Junhee Lee, Lakshay Gautam, and Manijeh Razeghi Junhee Lee, Manijeh RazeghiAppl. Phys. Lett. 123, 151902 (2023) https://doi.org/10.1063/5.0170383 ...[Visit Journal] We report high-quality Ga2O3 grown on an AlGaN/AlN/Sapphire in a single growth run in the same Metal Organic Chemical Vapor Deposition reactor with an AlOx interlayer at the Ga2O3/AlGaN interface. AlOx interlayer was found to enable the growth of single crystalline Ga2O3 on AlGaN in spite of the high lattice mismatch between the two material systems. The resulting nitride/oxide heterogenous heterostructures showed superior material qualities, which were characterized by structural, electrical, and optical characterization techniques. In particular, a significant enhancement of the electron mobility of the nitride/oxide heterogenous heterostructure is reported when compared to the individual electron mobilities of the Ga2O3 epilayer on the sapphire substrate and the AlGaN/AlN heterostructure on the sapphire substrate. This enhanced mobility marks a significant step in realizing the next generation of power electronic devices and transistors. [reprint (PDF)]
2.	Future of Al_xGa_1-xN Materials and Device Technology for Ultraviolet Photodetectors P. Kung, A. Yasan, R. McClintock, S. Darvish, K. Mi, and M. Razeghi SPIE Conference, San Jose, CA, Vol. 4650, pp. 199-- May 1, 2002 ...[Visit Journal] Design of the photodetector structure is one of the key issues in obtaining high performance devices; especially the thickness of the intrinsic region for p-i-n photodiodes is a crucial value and needs to be optimized. We compare the performance of the p-i-n photodiodes with different widths for the depletion region, which shows a trade-off between speed and responsivity of the devices. [reprint (PDF)]
2.	Investigation of impurities in type-II InAs/GaSb superlattices via capacitance-voltage measurement G. Chen, A. M. Hoang, S. Bogdanov, A. Haddadi, P. R. Bijjam, B.-M. Nguyen, and M. Razeghi Applied Physics Letters 103, 033512 (2013)-- July 17, 2013 ...[Visit Journal] Capacitance-voltage measurement was utilized to characterize impurities in the non-intentionally doped region of Type-II InAs/GaSb superlattice p-i-n photodiodes. Ionized carrier concentration versus temperature dependence revealed the presence of a kind of defects with activation energy below 6 meV and a total concentration of low 10¹⁵ cm⁻³. Correlation between defect characteristics and superlattice designs was studied. The defects exhibited a p-type behavior with decreasing activation energy as the InAs thickness increased from 7 to 11 monolayers, while maintaining the GaSb thickness of 7 monolayers. With 13 monolayers of InAs, the superlattice became n-type and the activation energy deviated from the p-type trend. [reprint (PDF)]
2.	High Detectivity InGaAs/InGaP Quantum-Dot Infrared Photodetectors Grown by Low Pressure Metalorganic Chemical Vapor Deposition J. Jiang, S. Tsao, T. O'Sullivan, W. Zhang, H. Lim, T. Sills, K. Mi, M. Razeghi, G.J. Brown, and M.Z. Tidrow Applied Physics Letters, 84 (12)-- April 22, 2004 ...[Visit Journal] We report a high detectivity middle-wavelength infrared quantum dot infrared photodetector (QDIP). The InGaAs quantum dots were grown by self-assembly on an InGaP matrix via low pressure metalorganic chemical vapor deposition. Photoresponse was observed at temperatures above 200 K with a peak wavelength of 4.7 µm and cutoff wavelength of 5.2 µm. The background limited performance temperature was 140 K, and this was attributed to the super low dark current observed in this QDIP. A detectivity of 3.6×10¹⁰ cm·Hz^½/W, which is comparable to the state-of-the-art quantum well infrared photodetectors in a similar wavelength range, was obtained for this InGaAs/InGaP QDIP at both T = 77 K and T = 95 K at biases of –1.6 and –1.4 V, [reprint (PDF)]
2.	The correlation between x-ray diffraction patterns and strain distribution inside GaInP/GaAs superlattices X.G. He, M. Erdtmann, R. Williams, S. Kim, and M. Razeghi Applied Physics Letters 65 (22)-- November 28, 1994 ...[Visit Journal] Strong correlation between x‐ray diffraction characteristics and strain distribution inside GaInP/GaAs superlattices has been reported. It is found that the symmetry of (002) diffraction patterns can be used to evaluate the interface strain status. A sample with no interfacial strains has a symmetric (002) diffraction pattern and weak (004) diffraction pattern. It is also demonstrated that strain distribution in superlattices can be readily estimated qualitatively by analyzing x-ray diffraction patterns. [reprint (PDF)]
2.	SOLID-STATE DEEP UV EMITTERS/DETECTORS: Zinc oxide moves further into the ultraviolet David J. Rogers; Philippe Bove; Eric V. Sandana; Ferechteh Hosseini Teherani; Ryan McClintock; Manijeh Razeghi Laser Focus World. 2013;49(10):33-36.-- October 10, 2013 ...[Visit Journal] Latest advancements in the alloying of zinc oxide (ZnO) with magnesium (Mg) can offer an alternative to (Al) GaN-based emitters/detectors in the deep UV with reduced lattice and efficiency issues. The emerging potential of ZnO for UV emitter and detector applications is the result of a long, concerted, and fruitful R&D effort that has led to more than 7000 publications in 2012. ZnO is considered to be a potentially superior material for use in LEDs and laser diodes due to its larger exciton binding energy, as compared with 21 meV for GaN. Wet etching is also possible for ZnO with nearly all dilute acids and alkalis, while GaN requires hydrofluoric (HF) acid or plasma etching. High-quality ZnO films can be grown more readily on mismatched substrates and bulk ZnO substrates have better availability than their GaN equivalents.
2.	High-temperature high-power continuous-wave operation of buried heterostructure quantum-cascade lasers A. Evans, J.S. Yu, J. David, L. Doris, K. Mi, S. Slivken, and M. Razeghi Applied Physics Letters, 84 (3)-- January 19, 2004 ...[Visit Journal] We report cw operation of buried heterostructure 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 333 K (60 °C). The high cw optical output powers of 446 mW at 293 K, 372 mW at 298 K, and 30 mW at 333 K are achieved with threshold current densities of 2.19, 2.35, and 4.29 kA/cm² respectively, for a high-reflectivity-coated, 9-µm-wide and 3-mm-long laser [reprint (PDF)]
2.	Anomalous Hall Effect in InSb Layers Grown by MOCVD on GaAs Substrates C. Besikci, Y.H. Choi, R. Sudharsanan, and M. Razeghi Journal of Applied Physics 73 (10)-- May 15, 1993 ...[Visit Journal] InSb epitaxial layers have been grown on GaAs substrates by low‐pressure metalorganic chemical vapor deposition. A 3.15 μm thick film yielded an x‐ray full width at half maximum of 171 arcsec. A Hall mobility of 76 200 cm²/V· s at 240 K and a full width at half maximum of 174 arcsec have been measured for a 4.85 μm thick epilayer. Measured Hall data have shown anomalous behavior. A decrease in Hall mobility with decreasing temperature has been observed and room‐temperature Hall mobility has increased with thickness. In order to explain the anomalous Hall data, and the thickness dependence of the measured parameters, the Hall coefficient and Hall mobility have been simulated using a three‐layer model including a surface layer, a bulklike layer, and an interface layer with a high density of defects. Theoretical analysis has shown that anomalous behavior can be attributed to donor-like defects caused by the large lattice mismatch and to a surface layer which dominates the transport in the material at low temperatures. [reprint (PDF)]
2.	High peak power 16 m InP-related quantum cascade laser A. Szerlinga,∗, S. Slivkenb, M. RazeghibaInstytut Opto-Electronics Review 25, pp. 205–208-- July 22, 2017 ...[Visit Journal] tIn this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with themaximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T₀) 272 K. Two types of the lasers were fabricatedand characterized: the lasers with a SiO₂ layer left untouched in the area of the metal-free window ontop of the ridge, and the lasers with the SiO₂layer removed from the metal-free window area. Dual-wavelength operation was obtained, at ∼15.6 μm (641 cm⁻¹) and at ∼16.6 μm (602 cm⁻¹) for laserswith SiO₂-removed, while within the emission spectrum of the lasers with SiO₂-left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO₂ layer showed ∼15% lower threshold current than these ones with the SiO₂ layer. The optical powers for lasers without SiO₂ layer were almost twice higher than for the lasers with the SiO₂ layer on the top of the ridge. [reprint (PDF)]
2.	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)]
2.	Low Dark Current Deep UV AlGaN Photodetectors on AlN Substrate Lakshay Gautam, Junhee Lee, Gail Brown, Manijeh Razeghi IEEE Journal of Quantum Electronics, vol. 58, no. 3, pp. 1-5, June 2022, Art no. 4000205 ...[Visit Journal] We report high quality, low dark current, deep Ultraviolet AlGaN/AlN Photodetectors on AlN substrate. AlGaN based Photodetectors are grown and fabricated both on AlN and Sapphire substrates with the same epilayer structure. Subsequently, electrical characteristics of both photodetectors on AlN substrate and Sapphire are compared. A reduction of 4 orders of magnitude of dark current density is reported in UV detectors grown on AlN substrate with respect to Sapphire substrate. [reprint (PDF)]
2.	State-of-the-art Type II Antimonide-based superlattice photodiodes for infrared detection and imaging M. Razeghi, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, S. Abdollahi Pour, P. Manurkar, and S. Bogdanov SPIE Proceedings, Nanophotonics and Macrophotonics for Space Environments II, San Diego, CA, Vol. 7467, p. 74670T-1-- August 5, 2009 ...[Visit Journal] Type-II InAs/GaSb Superlattice (SL), a system of multi interacting quantum wells was first introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this low dimensional system has drawn a lot of attention for its attractive quantum mechanics properties and its grand potential for the emergence into the application world, especially in infrared detection. In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs and imaging applications which elevated the performances of Type-II InAs/GaSb superlattice photodetectors to a comparable level to the state-of-the-art Mercury Cadmium Telluride. We will present in this talk the current status of the state-of-the-art Type II superlattice photodetectors and focal plane arrays, and the future outlook for this material system. [reprint (PDF)]
2.	Near bulk-limited R0A of long-wavelength infrared type-II InAs/GaSb superlattice photodiodes with polyimide surface passivation Andrew Hood, Pierre-Yves Delaunay, Darin Hoffman, Binh-Minh Nguyen, Yajun Wei, Manijeh Razeghi, and Vaidya Nathan Applied Physics Letters 90, 233513-- June 4, 2007 ...[Visit Journal] Effective surface passivation of Type-II InAs/GaSb superlattice photodiodes with cutoff wavelengths in the long-wavelength infrared is presented. A stable passivation layer, the electrical properties of which do not change as a function of the ambient environment nor time, has been prepared by a solvent-based surface preparation, vacuum desorption, and the application of an insulating polyimide layer. Passivated photodiodes, with dimensions ranging from 400×400 to 25×25 µm², with a cutoff wavelength of ~11 µm, exhibited near bulk-limited R₀A values of ~12 Ω·cm², surface resistivities in excess of 10⁴ Ω·cm, and very uniform current-voltage behavior at 77 K. [reprint (PDF)]
2.	Solar-blind photodetectors and focal plane arrays based on AlGaN R. McClintock, M. Razeghi Proc. SPIE 9555, Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications, 955502-- August 25, 2015 ...[Visit Journal] III-Nitride material system (AlGaInN) possesses unique optical, electrical and structural properties such as a wide tunable direct bandgap, inherent fast carrier dynamics; good carrier transport properties, high breakdown fields; and high robustness and chemical stability. Recent technological advances in the wide bandgap AlGaN portion of this material system have led to a renewed interest in ultraviolet (UV) photodetectors. These detectors find use in numerous applications in the defense, commercial and scientific arenas such as covert space-to-space communications, early missile threat detection, chemical and biological threat detection and spectroscopy, flame detection and monitoring, UV environmental monitoring, and UV astronomy.1,2,3 Back illuminated detectors operating in the solar blind region are of special interest. Back illumination allows the detector to be hybridized to a silicon read-out integrated circuit, epi-side down, and still collect light through the back of the transparent sapphire substrate. This allows the realization of solar blind focal plane arrays (FPAs) for imaging applications. Solar-blind FPAs are especially important because of the near total absence of any background radiation in this region. In this talk, we will present our recent back-illuminated solar-blind photodetector, mini-array, and FPA results. By systematically optimizing the design of the structure we have realized external quantum efficiencies (EQE) of in excess of 89% for pixel-sized detectors. Based on the absence of any anti-reflection coating, this corresponds to nearly 100% internal quantum efficiency. At the same time, the dark current remains below ~2 × 10^-9 A/cm² even at 10 volts of reverse bias. The detector has a very sharp falloff starting at 275 with the UV-solar rejection of better than three orders of magnitude, and a visible rejection ratio is more than 6 orders of magnitude. This high performance photodetector design was then used as the basis of the realization of solar-blind FPA. We demonstrated a 320×256 FPA with a peak detection wavelength of 278nm. The operability of the FPA was better than 92%, and excellent corrected imaging was obtained. [reprint (PDF)]
2.	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)]

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