Center for Quantum Devices - Most Downloaded Journal Articles

Page 9 of 30: Prev << 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 >> Next (739 Items)

17.	Recent advances in MOCVD growth of InxGa1-xAsyP1-y alloys M. Razeghi, J.P. Duchemin M. Razeghi, J.P. Duchemin, Recent advances in MOCVD growth of InxGa1-xAsyP1-y alloys, Journal of Crystal Growth, Volume 70, Issues 1–2, 1984, Pages 145-149,-- December 1, 1984 ...[Visit Journal] The low pressure metalorganic chemical vapour deposition (LPMOCVD) growth of GaxIn1-xAsyP1-y-InP lattice matched system, with high mobilities, sharp interfaces, low background doping densities, and the formation of a two-dimensional electron gas (2DEG) at the interfaces, has recently made spectacular advances, as in evidenced by the availability of high quality DH lasers, PIN photodiodes, and Gunn diodes. We present here some new results obtained on the above-mentioned material and devices. [reprint (PDF)]
17.	High-performance bias-selectable dual-band Short-/Mid-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb/AlSb Type-II superlattices M. Razeghi; A.M. Hoang; A. Haddadi; G. Chen; S. Ramezani-Darvish; P. Bijjam; P. Wijewarnasuriy; E. Decuir Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87041W (June 18, 2013)-- June 18, 2013 ...[Visit Journal] We report a bias selectable dual-band Type-II superlattice-based short-wave infrared (SWIR) and mid-wave infrared (MWIR) co-located photodetector capable of active and passive imaging. A new double-layer etch-stop scheme is introduced for back-side-illuminated photodetectors, 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 cut-off 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 (tint), which lowered to ∼13 mK at 110 K using and integration time of 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. An excellent imagery from the dual-band imager exemplifying pixel coincidence is shown. [reprint (PDF)]
17.	Demonstration of mid-infrared type-II InAs/GaSb superlattice photodiodes grown on GaAs substrate B.M. Nguyen, D. Hoffman, E.K. Huang, S. Bogdanov, P.Y. Delaunay, M. Razeghi and M.Z. Tidrow Applied Physics Letters, Vol. 94, No. 22-- June 8, 2009 ...[Visit Journal] We report the growth and characterization of type-II InAs/GaSb superlattice photodiodes grown on a GaAs substrate. Through a low nucleation temperature and a reduced growth rate, a smooth GaSb surface was obtained on the GaAs substrate with clear atomic steps and low roughness morphology. On the top of the GaSb buffer, a p⁺-i-n⁺ type-II InAs/GaSb superlattice photodiode was grown with a designed cutoff wavelength of 4 μm. The detector exhibited a differential resistance at zero bias (R₀A)in excess of 1600 Ω·cm² and a quantum efficiency of 36.4% at 77 K, providing a specific detectivity of 6 X 10¹¹ cm·Hz^½/W and a background limited operating temperature of 100 K with a 300 K background. Uncooled detectors showed similar performance to those grown on GaSb substrates with a carrier lifetime of 110 ns and a detectivity of 6 X 10⁸ cm·Hz^½/W. [reprint (PDF)]
17.	Microstrip Array Ring FETs with 2D p-Ga2O3 Channels Grown by MOCVD Manijeh Razeghi, Junhee Lee, Lakshay Gautam, Jean-Pierre Leburton, Ferechteh H. Teherani, Pedram Khalili Amiri, Vinayak P. Dravid and Dimitris Pavlidis Photonics 2021, 8(12), 578; ...[Visit Journal] Gallium oxide (Ga2O3) thin films of various thicknesses were grown on sapphire (0001) substrates by metal organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa), high purity deionized water, and silane (SiH4) as gallium, oxygen, and silicon precursors, respectively. N2 was used as carrier gas. Hall measurements revealed that films grown with a lower VI/III ratio had a dominant p-type conduction with room temperature mobilities up to 7 cm2/Vs and carrier concentrations up to ~1020 cm−3 for thinner layers. High resolution transmission electron microscopy suggested that the layers were mainly κ phase. Microstrip field-effect transistors (FETs) were fabricated using 2D p-type Ga2O3:Si, channels. They achieved a maximum drain current of 2.19 mA and an on/off ratio as high as ~108. A phenomenological model for the p-type conduction was also presented. As the first demonstration of a p-type Ga2O3, this work represents a significant advance which is state of the art, which would allow the fabrication of p-n junction based devices which could be smaller/thinner and bring both cost (more devices/wafer and less growth time) and operating speed (due to miniaturization) advantages. Moreover, the first scaling down to 2D device channels opens the prospect of faster devices and improved heat evacuation [reprint (PDF)]
17.	High Frequency Extended Short-Wavelength Infrared Heterojunction Photodetectors Based on InAs/GaSb/AlSb Type-II Superlattices Romain Chevallier, Abbas Haddadi, Ryan McClintock, Arash Dehzangi , Victor Lopez-Dominguez, Pedram Khalili Amiri, Manijeh Razeghi IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 54, NO. 6-- December 1, 2018 ...[Visit Journal] InAs/GaSb/AlSb type-II superlattice-based photodetectors, with 50% cut-off wavelength of 2.1 µm and a −3 dB cut-off frequency of 4.8 GHz, are demonstrated, for 10 µm diameter circular mesas under 15 V applied reverse bias. A study of the cut-off frequency with applied bias and mesa size was performed to evaluate some of the limiting factors of photodetectors high frequency performance. [reprint (PDF)]
17.	8-13 μm InAsSb heterojunction photodiode operating at near room temperature J.D. Kim, S. Kim, D. Wu, J. Wojkowski, J. Xu, J. Piotrowski, E. Bigan, and M. Razeghi Applied Physics Letters 67 (18)-- October 30, 1995 ...[Visit Journal] p⁺-InSb/π-InAs_1−xSb_x/n⁺-InSb heterojunction photodiodes operating at near room temperature in the 8–13 μm region of infrared (IR) spectrum are reported. A room‐temperature photovoltaic response of up to 13 μm has been observed at 300 K with an x≊0.85 sample. The voltage responsivity‐area product of 3×10⁻⁵ V· cm²/W has been obtained at 300 K for the λ=10.6 μm optimized device. This was close to the theoretical limit set by the Auger mechanism, with a detectivity at room temperature of ≊1.5×10⁸ cm ·Hz^½/W. [reprint (PDF)]
17.	First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands M. Razeghi; J. P. Duchemin; J. C. Portal; L. Dmowski; G. Remeni; R. J. Nicholas; A. Briggs M. Razeghi, J. P. Duchemin, J. C. Portal, L. Dmowski, G. Remeni, R. J. Nicholas, A. Briggs; First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands. Appl. Phys. Lett. 17 March 1986; 48 (11)-- March 17, 1986 ...[Visit Journal] Shubnikov–de Haas and quantum Hall effects have been studied in GaInAs‐InP heterojunctions grown by modified low pressure metalorganic chemical vapor deposition. In contrast to the results reported up till now on GaInAs‐InP heterojunctions with nearly the same channel electron density, not one but three electric subbands, E0, E1, and E2, are occupied in zero magnetic field. Two electric subbands E0 and E1 contribute to the quantum Hall effect. Magnetic depopulation of the higher (E1 and E2) subbands is observed in both perpendicular and tilted magnetic field orientations. This enables a demonstration of the importance of intersubband scattering in resistivity and cyclotron resonance. [reprint (PDF)]
17.	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)]
17.	Solar-blind photodetectors based on Ga₂O₃ and III-nitrides Ryan McClintock; Alexandre Jaud; Lakshay Gautam; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128803-- January 31, 2020 ...[Visit Journal] Recently, there has been a surge of interest in the wide bandgap semiconductors for solar blind photo detectors (SBPD). This work presents our recent progress in the growth/doping of AlGaN and Ga₂O₃ thin films for solar blind detection applications. Both of these thin films grown are grown by metal organic chemical vapor deposition (MOCVD) in the same Aixtron MOCVD system. Solar-blind metal-semiconductor-metal photodetectors were fabricated with Ga₂O₃. Spectral responsivity studies of the MSM photodetectors revealed a peak at 261 nm and a maximum EQE of 41.7% for a −2.5 V bias. We have also demonstrated AlGaN based solar-blind avalanche photodiodes with a gain in excess of 57,000 at ~100 volts of reverse bias. This gain can be attributed to avalanche multiplication of the photogenerated carriers within the device. Both of these devices show the potential of wide bandgap semiconductors for solar blind photo detectors. [reprint (PDF)]
17.	Material and design engineering of (Al)GaN for high-performance avalanche photodiodes and intersubband applications M. Razeghi and C. Bayram SPIE Proceedings, Dresden, Germany (May 4-6, 2009), Vol. 7366, p. 73661F-1-- May 20, 2009 ...[Visit Journal] Numerous applications in scientific, medical, and military areas demand robust, compact, sensitive, and fast ultraviolet (UV) detection. Our (Al)GaN photodiodes pose high avalanche gain and single-photon detection efficiency that can measure up to these requirements. Inherit advantage of back-illumination in our devices offers an easier integration and layout packaging via flip-chip hybridization for UV focal plane arrays that may find uses from space applications to hostile-agent detection. Thanks to the recent (Al)GaN material optimization, III-Nitrides, known to have fast carrier dynamics and short relaxation times, are employed in (Al)GaN based superlattices that absorb in near-infrared regime. In this work, we explain the origins of our high performance UV APDs, and employ our (Al)GaN material knowledge for intersubband applications. We also discuss the extension of this material engineering into the far infrared, and even the terahertz (THz) region. [reprint (PDF)]
17.	Al_xGa_1-xN (0 ≤ x ≤ 1) Ultraviolet Photodetectors Grown on Sapphire by Metal-organic Chemical-vapor Deposition D. Walker, X. Zhang, A. Saxler, P. Kung, J. Xu, and M. Razeghi Applied Physics Letters 70 (8)-- February 24, 1997 ...[Visit Journal] Al_xGa_1–xN (0 ≤ x ≤ 1) ultraviolet photoconductors with cutoff wavelengths from 365 to 200 nm have been fabricated and characterized. The maximum detectivity reached 5.5 × 10⁸ cm·Hz^1/2/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 ms. The frequency-dependent noise spectrum shows that it is dominated by Johnson noise at high frequencies for low-Al-composition samples. [reprint (PDF)]
17.	Compressively-strained multiple quantum well InAsSb lasers emitting at 3.6 μm grown by metal-organic chemical vapor deposition B. Lane, D. Wu, A. Rybaltowski, H. Yi, J. Diaz, and M. Razeghi Applied Physics Letters 70 (4)-- January 27, 1997 ...[Visit Journal] A compressively strained InAsSb/InAs multiple quantum-well (MQW) structure was grown by low-pressure metal-organic chemical vapor deposition. Maximum output power (from two facets) up to 1 W with differential efficiency about 70% was obtained from a MQW laser with stripe width of 100 μm and cavity length of 700 μm for emitting wavelength of 3.65 μm at 90 K in pulse mode operation. About 2 times lower threshold current density was obtained from the MQW lasers for a temperature range of 90 to 140 K compared to the double heterostructure lasers grown on the same growth conditions. [reprint (PDF)]
17.	ZnO Thin Film Templates for GaN-based Devices D.J. Rogers, F. Hosseini Teherani, A. Yasan, R. McClintock, K. Mayes, S.R. Darvish, P. Kung, M. Razeghi and G. Garry SPIE Conference, Jose, CA, Vol. 5732, pp. 412-- January 22, 2005 ...[Visit Journal] GaN-based optoelectronic devices are plagued by a tendency to non-radiative transitions linked to defects in the active layers. ZnO is promising as a substrate material for GaN because it has the same wurtzite structure and a relatively small lattice mismatch (~1.8%). In this paper, we discuss use of ZnO thin films as templates for GaN based LED. [reprint (PDF)]
17.	Type-II ‘M’ Structure Photodiodes: An Alternative Material Design for Mid-Wave to Long Wavelength Infrared Regimes B-M. Nguyen, M. Razeghi, V. Nathan, and G.J. Brown SPIE Conference, January 25-29, 2007, San Jose, CA Proceedings – Quantum Sensing and Nanophotonic Devices IV, Vol. 6479, p. 64790S-1-10-- January 29, 2007 ...[Visit Journal] In this work, an AlSb-containing Type-II InAs/GaSb superlattice, the so-called M-structure, is presented as a candidate for mid and long wavelength infrared detection devices. The effect of inserting an AlSb barrier in the GaSb layer is discussed and predicts many promising properties relevant to practical use. A good agreement between the theoretical calculation based on Empirical Tight Binding Method framework and experimental results is observed, showing the feasibility of the structure and its properties. A band gap engineering method without material stress constraint is proposed. [reprint (PDF)]
17.	High operability 1024 x 1024 long wavelength Type-II superlattice focal plane array A. Haddadi, S.R. Darvish, G. Chen, A.M. Hoang, B.M. Nguyen and M. Razeghi IEEE Journal of Quantum Electronics (JQE), Vol. 48, No. 2, p. 221-228-- February 10, 2012 ...[Visit Journal] Electrical and radiometric characterization results of a high-operability 1024 x 1024 long wavelength infrared type-II superlattice focal plane array are described. It demonstrates excellent quantum efficiency operability of 95.8% and 97.4% at operating temperatures of 81 K and 68 K, respectively. The external quantum efficiency is 81% without any antireflective coating. The dynamic range is 37 dB at 81 K and increases to 39 dB at 68 K operating temperature. The focal plane array has noise equivalent temperature difference as low as 27 mK and 19 mK at operating temperatures of 81 K and 68 K, respectively, using f/2 optics and an integration time of 0.13 ms. [reprint (PDF)]
17.	Graphene versus oxides for transparent electrode applications Sandana, V. E.; Rogers, D. J.; Teherani, F. Hosseini; Bove, P.; Razeghi, M. Proc. SPIE 8626, Oxide-based Materials and Devices IV, 862603 (March 18, 2013)-- March 18, 2013 ...[Visit Journal] Due to their combination of good electrical conductivity and optical transparency, Transparent Conducting Oxides (TCOs) are the most common choice as transparent electrodes for optoelectronics applications. In particular, devices, such as LEDs, LCDs, touch screens and solar cells typically employ indium tin oxide. However, indium has some significant drawbacks, including toxicity issues (which are hampering manufacturing), an increasing rarefication (due to a combination of relative scarcity and increasing demand [1]) and resulting price increases. Moreover, there is no satisfactory option at the moment for use as a p-type transparent contact. Thus alternative materials solutions are actively being sought. This review will compare the performance and perspectives of graphene with respect to TCOs for use in transparent conductor applications. [reprint (PDF)]
17.	Quantum hall effect and hopping conduction in InxGa1−xAs-InP heterojunctions at low temperature Y. Guldner, J.P. Hirtz, A. Briggs, J.P. Vieren, M. Voos, M. Razeghi Y. Guldner, J.P. Hirtz, A. Briggs, J.P. Vieren, M. Voos, M. Razeghi, Quantum hall effect and hopping conduction in InxGa1−xAs-InP heterojunctions at low temperature, Surface Science, Volume 142, Issues 1–3, 1984, Pages 179-181,-- July 1, 1984 ...[Visit Journal] We report investigations of the temperature dependence of the quantum Hall effect in modulation doped InxGa1−xAs-InP heterojunctions. The diagonal conductivity σxx is studied at several minima of the magneto-resistance ϱxx between 50 mK and 2 K. A hopping conduction mechanism is observed when the Fermi level is in the tail of the Landau levels. [reprint (PDF)]
17.	High performance quantum dot-quantum well infrared focal plane arrays S. Tsao, A. Myzaferi, and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7605, p. 76050J-1-- January 27, 2010 ...[Visit Journal] Quantum dot (QD) devices are a promising technology for high operating temperature detectors. We have studied InAs QDs embedded in an InGaAs/InAlAs quantum well structure on InP substrate for middle wavelength infrared detectors and focal plane arrays (FPAs). This combined dot-well structure has weak dot confinement of carriers, and as a result, the device behavior differs significantly from that in more common dot systems with stronger confinement. We report on our studies of the energy levels in the QDWIP devices and on QD-based detectors operating at high temperature with D* over 10¹⁰ cm·Hz^½/W at 150 K operating temperature and high quantum efficiency over 50%. FPAs have been demonstrated operating at up to 200 K. We also studied two methods of adapting the QDWIP device to better accommodate FPA readout circuit limitations. [reprint (PDF)]
17.	Effect of contact doping on superlattice-based minority carrier unipolar detectors B.M. Nguyen, G. Chen, A.M. Hoang, S. Abdollahi Pour, S. Bogdanov, and M. Razeghi Applied Physics Letters, Vol. 99, No. 3, p. 033501-1-- July 18, 2011 ...[Visit Journal] We report the influence of the contact doping profile on the performance of superlattice-based minority carrier unipolar devices for mid-wave infrared detection. Unlike in a photodiode, the space charge in the p-contact of a pMp unipolar device is formed with accumulated mobile carriers, resulting in higher dark current in the device with highly doped p-contact. By reducing the doping concentration in the contact layer, the dark current is decreased by one order of magnitude. At 150 K, 4.9 μm cut-off devices exhibit a dark current of 2 × 10⁻⁵A/cm² and a quantum efficiency of 44%. The resulting specific detectivity is 6.2 × 10¹¹ cm·Hz^1/2/W at 150 K and exceeds 1.9 × 10¹⁴ cm·Hz^1/2/W at 77 K. [reprint (PDF)]
17.	High Power 3-12 μm Infrared Lasers: Recent Improvements and Future Trends M. Razeghi, S. Slivken, A. Tahraoui, A. Matlis, and Y.S. Park Advanced Research Workshop on Semiconductor Nanostructures, Queenstown, New Zealand; Proceedings -- February 5, 2003 ...[Visit Journal] In this paper, we discuss the progress of quantum cascade lasers (QCLs) grown by gas-source molecular beam epitaxy. Room temperature QCL operation has been reported for lasers emitting between 5-11 μm, with 9-11 μm lasers operating up to 425 K. Laser technology for the 3-5 μm range takes advantage of a strain-balanced active layer design. We also demonstrate record room temperature peak output powers at 9 and 11 μm (2.5 and 1 W, respectively) as well as record low 80K threshold current densities (250 A/cm²) for some laser designs. Preliminary distributed feedback (DFB) results are also presented and exhibit single mode operation for 9 μm lasers at room temperature. [reprint (PDF)]
17.	High Performance InAs/GaSb Superlattice Photodiodes for the Very Long Wavelength Infrared Range H. Mohseni, M. Razeghi, G.J. Brown, Y.S. Park Applied Physics Letters 78 (15)-- April 9, 2001 ...[Visit Journal] We report on the demonstration of high-performance p-i-n photodiodes based on type-II InAs/GaSb superlattices with 50% cut-off wavelength λ_c = 16 μm operating at 80 K. Material is grown by molecular beam epitaxy on GaSb substrates with excellent crystal quality as evidenced by x-ray diffraction and atomic force microscopy. The processed devices show a current responsivity of 3.5 A/W at 80 K leading to a detectivity of ∼ 1.51×10¹⁰ cm·Hz^½/W. The quantum efficiency of these devices is about 35% which is comparable to HgCdTe detectors with a similar active layer thickness. [reprint (PDF)]
17.	Advances in UV sensitive visible blind GaN-based APDs M. Ulmer, R. McClintock and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-27, 2011), Vol. 7945, p. 79451G-- January 23, 2011 ...[Visit Journal] In this paper, we describe our current state-of-the-art process of making visible-blind APDs based on GaN. We have grown our material on both conventional sapphire and low dislocation density free-standing c- and m-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs are compared. The spectral response and Geiger-mode photon counting performance of UV APDs are studied under low photon fluxes. Single photon detection capabilities with over 30% are demonstrated. We show how with pulse height discrimination the Geiger-mode operation conditions can be optimized for enhanced SPDE versus dark counts. [reprint (PDF)]
17.	A detailed analysis of carrier transport in InAs0.3Sb0.7 layers grown on GaAs substrates by metalorganic chemical vapor deposition C. Besikci, Y.H. Choi, G. Labeyrie, E. Bigan and M. Razeghi with J.B. Cohen, J. Carsello, and V.P. Dravid Journal of Applied Physics 76 (10)-- November 15, 1994 ...[Visit Journal] InAs_0.3Sb_0.7 layers with mirrorlike morphology have been grown on GaAs substrates by low‐pressure metalorganic chemical vapor deposition. A room‐temperature electron Hall mobility of 2×10⁴ cm²/V· s has been obtained for a 2 μm thick layer. Low‐temperature resistivity of the layers depended on TMIn flow rate and layer thickness. Hall mobility decreased monotonically with decreasing temperature below 300 K. A 77 K conductivity profile has shown an anomalous increase in the sample conductivity with decreasing thickness except in the near vicinity of the heterointerface. In order to interpret the experimental data, the effects of different scattering mechanisms on carrier mobility have been calculated, and the influences of the lattice mismatch and surface conduction on the Hall measurements have been investigated by applying a three‐layer Hall‐effect model. Experimental and theoretical results suggest that the combined effects of the dislocations generated by the large lattice mismatch and strong surface inversion may lead to deceptive Hall measurements by reflecting typical n‐type behavior for a p‐type sample, and the measured carrier concentration may considerably be affected by the surface conduction up to near room temperature. A quantitative analysis of dislocation scattering has shown significant degradation in electron mobility for dislocation densities above 10⁷ cm⁻². The effects of dislocation scattering on hole mobility have been found to be less severe. It has also been observed that there is a critical epilayer thickness (∼1 μm) below which the surface electron mobility is limited by dislocation scattering. [reprint (PDF)]
17.	Elimination of surface leakage in gate controlled Type-II InAs/GaSb mid-infrared photodetectors G. Chen, B.-M. Nguyen, A.M. Hoang, E.K. Huang, S.R. Darvish, and M. Razeghi Applied Physics Letters, Vol. 99, No. 18, p. 183503-1-- October 31, 2011 ...[Visit Journal] The electrical performance of mid-infrared type-II superlattice M-barrier photodetectors is shown to be limited by surface leakage. By applying gate bias on the mesa sidewall surface, leakage current is significantly reduced. Qualitatively IV modeling shows diffusion-dominated behavior of dark current at temperatures greater than 120 K. At 110 K, the dark current of gated device is reduced by more than 2 orders of magnitude, reaching the measurement system noise floor. With a quantum efficiency of 48% in front side illumination configuration, a 4.7μm cut-off gated device attains a specific detectivity of 2.5 × 10¹⁴ cm·Hz^½·W^-1 at 110 K, which is 3.6 times higher than in ungated devices. [reprint (PDF)]
17.	High power, continuous wave, room temperature operation of λ ~ 3.4 μm and λ ~ 3.55 μm InP-based quantum cascade lasers N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 100, No. 21, p. 212104-1-- May 21, 2012 ...[Visit Journal] We report two highly strain-balanced InP-based AlInAs/GaInAs quantum cascade lasers emitting near 3.39 and 3.56 . A pulsed threshold current density of only 1.1 kA/cm² has been achieved at room temperature for both lasers with characteristic temperatures (T₀) of 166 K and 152 K, respectively. The slope efficiency is also relatively temperature insensitive with characteristic temperatures (T₁) of 116 K and 191 K, respectively. Continuous wave powers of 504 mW and 576 mW are obtained at room temperature, respectively. This was accomplished without buried ridge processing. [reprint (PDF)]

Page 9 of 30: Prev << 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 >> Next (739 Items)