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13.  Progress in monolithic, broadband, widely tunable midinfrared quantum cascade lasers
Manijeh Razeghi Wenjia Zhou Ryan McClintock Donghai Wu Steven Slivken
Optical Engineering 57(1), 011018-- December 1, 2017 ...[Visit Journal]
We present recent progress on the development of monolithic, broadband, widely tunable midinfrared quantum cascade lasers. First, we show a broadband midinfrared laser gain realized by a heterogeneous quantum cascade laser based on a strain balanced composite well design of Al0.63In0.37As∕Ga0.35In0.65As∕ Ga0.47In0.53As. Single mode emission between 5.9 and 10.9 μm under pulsed mode operation was realized from a distributed feedback laser array, which exhibited a flat current threshold across the spectral range. Using the broadband wafer, a monolithic tuning between 6.2 and 9.1 μm was demonstrated from a beam combined sampled grating distributed feedback laser array. The tunable laser was utilized for a fast sensing of methane under pulsed operation. Transmission spectra were obtained without any moving parts, which showed excellent agreement to a standard measurement made by a Fourier transform infrared spectrometer. [reprint (PDF)]
 
13.  Phase-matched optical second-harmonic generation in GaN and AlN slab waveguides
D.N. Hahn, G.T. Kiehne, G.K.L. Wong, J.B. Ketterson, P. Kung, A. Saxler and M. Razeghi
Journal of Applied Physics 85 (5)-- March 1, 1999 ...[Visit Journal]
Phase-matched optical second-harmonic (SH) generation was observed in GaN and AlN slab waveguides. Phase matching was achieved by waveguide modal dispersion. By tuning the output wavelength of an optical parametric amplifier, several phased-matched SH peaks were observed in the visible spectrum covering blue to red wavelengths. The peak positions are in agreement with the values calculated using the dispersive refractive indices of the film and substrate materials. [reprint (PDF)]
 
13.  GaN-based nanostructured photodetectors
J.L. Pau, C. Bayram, P. Giedraitis, R. McClintock, and M. Razeghi
SPIE Proceedings, San Jose, CA Volume 7222-14-- January 26, 2009 ...[Visit Journal]
The use of nanostructures in semiconductor technology leads to the observation of new phenomena in device physics. Further quantum and non-quantum effects arise from the reduction of device dimension to a nanometric scale. In nanopillars, quantum confinement regime is only revealed when the lateral dimensions are lower than 50 nm. For larger mesoscopic systems, quantum effects are not observable but surface states play a key role and make the properties of nanostructured devices depart from those found in conventional devices. In this work, we present the fabrication of GaN nanostructured metal-semiconductor-metal (MSM) and p-i-n photodiodes (PIN PDs) by e-beam lithography, as well as the investigation of their photoelectrical properties at room temperature. The nanopillar height and diameter are about 520 nm and 200 nm, respectively. MSMs present dark currents densities of 0.4 A/cm2 at ±100 V. A strong increase of the optical response with bias is observed, resulting in responsivities higher than 1 A/W. The relationship between this gain mechanism and surface states is discussed. PIN PDs yield peak responsivities (Rpeak) of 35 mA/W at -4 V and show an abnormal increase of the response (Rpeak > 100 A/W) under forward biases. [reprint (PDF)]
 
13.  High performance focal plane array based on type-II InAs/GaSb superlattice heterostructures
P.Y. Delaunay and M. Razeghi
SPIE Conference, January 20-25, 2008, San Jose, CA Proceedings – Quantum Sensing and Nanophotonic Devices V, Vol. 6900, p. 69000M-1-10.-- February 1, 2008 ...[Visit Journal]
Recent progress in growth techniques, structure design and processing has lifted the performances of Type-II InAs/GaSb superlattice photodetectors. A double heterostructure design, based on a low band gap (11 µm) active region and high band gap (5 µm) superlattice contacts, reduced the sensitivity of the superlattice to surface effects. The heterodiodes with an 11 µm cutoff, passivated with SiO2, presented similar performances to unpassivated devices and a one order of magnitude increase of the resistivity of the sidewalls, even after flip-chip bonding and underfill. Thanks to this new design and to the inversion of the polarity of the devices, a high performance focal plane array with an 11 µm cutoff was demonstrated. The noise equivalent temperature difference was measured as 26 mK and 19 mK for operating temperatures of 81 K and 67 K. At an integration time of 0.08 ms, the FPA presented a quantum efficiency superior to 50%. [reprint (PDF)]
 
13.  Passivation of type-II InAs/GaSb double heterostructure
P.Y. Delaunay, A. Hood, B.M. Nguyen, D. Hoffman, Y. Wei, and M. Razeghi
Applied Physics Letters, Vol. 91, No. 9, p. 091112-1-- August 27, 2007 ...[Visit Journal]
Focal plane array fabrication requires a well passivated material that is resistant to aggressive processes. The authors report on the ability of type-II InAs/GaSb superlattice heterodiodes to be more resilient than homojunctions diodes in improving sidewall resistivity through the use of various passivation techniques. The heterostructure consisting of two wide band gap (5 µm) superlattice contacts and a low band gap active region (11 µm) exhibits an R0A averaging of 13·Ω cm2. The devices passivated with SiO2, Na2S and SiO2 or polyimide did not degrade compared to the unpassivated sample and the resistivity of the sidewalls increased to 47 kΩ·cm. [reprint (PDF)]
 
13.  Schottky barrier heights and conduction-band offsets of In1-xGaxAs1-yPy lattice matched to GaAs
J.K. Lee, Y.H. Cho, B.D. Choe, K.S. Kim, H.I. Jeon, H. Lim and M. Razeghi
Applied Physics Letters 71 (7)-- August 18, 1997 ...[Visit Journal]
The Schottky barrier heights of Au/In1−xGaxAs1−yPy contacts have been determined as a function of y by the capacitance–voltage and temperature dependent current–voltage characteristics measurements. The barrier height is observed to increase as y is increased for both n- and p-type materials, with a more rapid increase for the p-type material. The compositional variation of the barrier heights for Au/n-In1−xGaxAs1−yPy is found to be identical to that of the conduction-band offsets in In1−xGaxAs1−yPy/GaAs heterojunctions. A possible cause of this phenomenon is also discussed. [reprint (PDF)]
 
13.  Evaluating the size-dependent quantum efficiency loss in a SiO2-Y2O3 hybrid gated type-II InAs/GaSb long-infrared photodetector array
G. Chen , A. M. Hoang , and M. Razeghi
Applied Physics Letters 104 , 103509 (2014)-- March 14, 2014 ...[Visit Journal]
Growing Y2O3 on 20 nm SiO2 to passivate a 11 μm 50% cut-off wavelength long-wavelength infrared type-II superlattice gated photodetector array reduces its saturated gate bias (VGsat ) to −7 V. Size-dependent quantum efficiency (QE) losses are evaluated from 400 μm to 57 μm size gated photodiode. Evolution of QE of the 57 μm gated photodiode with gate bias and diode operation bias reveals different surface recombination mechanisms. At 77 K and VG,sat , the 57 μm gated photodiode exhibits QE enhancement from 53% to 63%, and it has 1.2 × 10−5 A/cm² dark current density at −200 mV, and a specific detectivity of 2.3 × 1012 Jones. [reprint (PDF)]
 
13.  High Performance Planar Antimony-Based Superlattice Photodetectors Using Zinc Diffusion Grown by MBE
Jiakai Li, R. K. Saroj, Steven Slivken, V. H. Nguyen, Gail Brown and Manijeh Razeghi
Photonics 2022, 9, 664 ...[Visit Journal]
In this letter, we report a mid-wavelength infrared (MWIR) planar photodetector based on InAs/InAsSb type-II superlattices (T2SLs) that has a cut-off wavelength of 4.3 um at 77 K. The superlattice for the device was grown by molecular beam epitaxy while the planar device structure was achieved by Zinc diffusion process in a metal–organic chemical vapor deposition reactor. At 77 K, the peak responsivity and the corresponding quantum efficiency had the value of 1.42 A/W and 48% respectively at 3.7 um under -20 mV for the MWIR planar photodetector. At 77 K, the MWIR planar photodetector exhibits a dark current density of 2.0E5 A/cm^2 and the R0A value of ~3.0E2 Ohm cm^2 under -20 mV, which yielded a specific detectivity of 4.0E11 cm Hz^(1/2)/W at 3.7 um. At 150 K, the planar device showed a dark current density of 6.4E-5 A/cm^2 and a quantum efficiency of 49% at ~3.7 um under -20 mV, which yielded a specific detectivity of 2.0E11 cm Hz^(1/2)/W. [reprint (PDF)]
 
13.  Recent advances in III-Nitride materials, characterization and device applications
M. Razeghi, X. Zhang, P. Kung, A. Saxler, D. Walker, K.Y. Lim, and K.S. Kim
SPIE Conference: Solid State Crystals in Optoelectronics and Semiconductor Technology; Proceedings 3179-- October 7, 1996 ...[Visit Journal]
High-quality AlN, GaN, AlGaN have been grown on sapphire substrate by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The x-ray rocking curve of AlN and GaN were 100 arcsecs and 30 arcsecs respectively with Pendelloesung oscillations, which are the best reported to date. GaN with high crystallinity simultaneously exhibited high optical and electrical quality. Photoluminescence linewidth of GaN at 77K was as low as 17 meV, which is the best reported to date. Si-doped GaN had a mobility higher than 300 cm²/V·s. GaN has been also successfully grown on LiGaO2 substrate with LP-MOCVD for the first time. AlGaN for the entire composition range has been grown. These layers exhibited the lowest x-ray FWHM reported to date. The excellent optical quality of these layers have been characterized by room temperature UV transmission and photoluminescence. N-type doping of AlGaN with Si has ben achieved up to 60 percent Al with mobility as high as 78 cm²/V·s. AlxGa1-xN/AlyGa1-yN superlattice with atomically sharp interface have been demonstrated. Optically-pumped stimulated emission in GaN:Ge and GaN:Si has been observed with threshold optical power density as low as 0.4 MW/cm². AlGaN photoconductors with cut-off wavelengths from 200 nm to 365 nm have been achieved for the first time. GaN p-n junction photovoltaic detector with very selective photoresponse have been demonstrated and theoretically modeled. Ti/AlN/Si metal-insulator- semiconductor capacitor with high capacitance-voltage performances at both low and high frequencies and low interface trap level density have been demonstrated for the first time in this material system. [reprint (PDF)]
 
13.  Photovoltaic effects in GaN structures with p-n junction
X. Zhang, P. Kung, D. Walker, J. Piotrowski, A. Rogalski, A. Saxler, and M. Razeghi
Applied Physics Letters 67 (14)-- October 2, 1995 ...[Visit Journal]
Large-area GaN photovoltaic structures with p-n junctions have been fabricated using atmospheric pressure metalorganic chemical vapor deposition. The photovoltaic devices typically exhibit selective spectral characteristics with two narrow peaks of opposite polarity. This can be related to p-n junction connected back‐to‐back with a Schottky barrier. The shape of the spectral characteristic is dependent on the thickness of the n- and p-type regions. The diffusion length of holes in the n-type GaN region, estimated by theoretical modeling of the spectral response shape, was about 0.1 μm. [reprint (PDF)]
 
13.  Energy harvesting from millimetric ZnO single wire piezo-generators
Rogers, D. J.; Carroll, C.; Bove, P.; Sandana, V. E.; Goubert, L.; Largeteau, A.; Teherani, F. Hosseini; Demazeau, G.; McClintock, R.; Drouhin, H.-J.; Razeghi, M.
Oxide-based Materials and Devices III. Edited by Teherani, Ferechteh H.; Look, David C.; Rogers, David J. Proceedings of the SPIE, Volume 8263, article id. 82631X, 7 pp. (2012).-- February 9, 2013 ...[Visit Journal]
This work reports on investigations into the possibility of harvesting energy from the piezoelectric response of millimetric ZnO rods to movement. SEM & PL studies of hydrothermally grown ZnO rods revealed sizes ranging from 1 - 3 mm x 100 - 400 microns and suggested that each was a wurtzite monocrystal. Studies of current & voltage responses as a function of time during bending with a probe arm gave responses coherent with those reported elsewhere in the literature for ZnO nanowires or micro-rod single wire generators. The larger scale of these rods provided some advantages over such nano- and microstructures in terms of contacting ease, signal level & robustness. [reprint (PDF)]
 
13.  Gain and recombination dynamics in photodetectors made with quantum nanostructures: the quantum dot in a well and the quantum well
B. Movaghar, S. Tsao, S. Abdollahi Pour, T. Yamanaka, and M. Razeghi
Virtual Journal of Nanoscale Science & Technology, Vol. 18, No. 14-- October 6, 2008 ...[Visit Journal][reprint (PDF)]
 
13.  Passivation of Type-II InAs/GaSb Superlattice Photodiodes
A. Gin, Y. Wei, J. Bae, A. Hood, J. Nah, and M. Razeghi
International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego, CA; Thin Solid Films 447-448-- January 30, 2004 ...[Visit Journal]
Recently, excellent infrared detectors have been demonstrated using Type-II InAs/GaSb superlattice materials sensitive at wavelengths from 3 μm to greater than 32 μm. These results indicate that Type-II superlattice devices may challenge the preponderance of HgCdTe and other state-of-the-art infrared material systems. As such, surface passivation is becoming an increasingly important issue as progress is made towards the commercialization of Type-II devices and focal plane array applications. This work focuses on initial attempts at surface passivation of Type-II InAs/GaSb superlattice photodiodes using PECVD-grown thin layers of SiO2. Our results indicate that silicon dioxide coatings deposited at various temperatures improve photodetector resistivity by several times. Furthermore, reverse-bias dark current has been reduced significantly in passivated devices. [reprint (PDF)]
 
13.  High‐purity GaAs layers grown by low‐pressure metalorganic chemical vapor deposition
M. Razeghi; F. Omnes; J. Nagle; M. Defour; O. Acher; P. Bove
Appl. Phys. Lett. 55, 1677–1679 (1989)-- October 16, 1989 ...[Visit Journal]
We report electrical and optical properties of very high purity GaAs epilayers grown by low‐pressure metalorganic chemical vapor deposition using AsH3 and triethylgallium as As and Ga sources. An electron mobility of 335 000 cm2/V s at 38 K has been measured for a 12‐μ‐thick layer. [reprint (PDF)]
 
13.  High operating temperature midwave infrared photodiodes and focal plane arrays based on type-II InAs/GaSb superlattices
S. Abdollahi Pour, E.K. Huang, G. Chen, A. Haddadi, B.M. Nguyen and M. Razeghi
Applied Physics Letters, Vol. 98, No. 14, p. 143501-1-- April 4, 2011 ...[Visit Journal]
The dominant dark current mechanisms are identified and suppressed to improve the performance of midwave infrared InAs/GaSb Type-II superlattice photodiodes at high temperatures. The optimized heterojunction photodiode exhibits a quantum efficiency of 50% for 2 μm thick active region without any bias dependence. At 150 K, R0A of 5100 Ω·cm² and specific detectivity of 1.05×1012 cm·Hz0.5·W-1 are demonstrated for a 50% cutoff wavelength of 4.2 μm. Assuming 300 K background temperature and 2π field of view, the performance of the detector is background limited up to 180 K, which is improved by 25 °C compared to the homojunction photodiode. Infrared imaging using f/2.3 optics and an integration time of 10.02 ms demonstrates a noise equivalent temperature difference of 11 mK at operating temperatures below 120 K. [reprint (PDF)]
 
13.  High Power 0.98 μm GaInAs/GaAs/GaInP Multiple Quantum Well Laser
K. Mobarhan, M. Razeghi, G. Marquebielle and E. Vassilaki
Journal of Applied Physics 72 (9)-- November 1, 1992 ...[Visit Journal]
We report the fabrication of high quality Ga0.8In0.2As/GaAs/Ga0.51In0.49P multiple quantum well laser emitting at 0.98 μm grown by low pressure metalorganic chemical vapor deposition. Continuous wave operation with output power of 500 mW per facet was achieved at room temperature for a broad area laser with 130 μm width and 300 μm cavity length. This is an unusually high value of output power for this wavelength laser in this material system. The differential quantum efficiency exceeded 75% with excellent homogeneity and uniformity. The characteristic temperature, T0 was in the range of 120–130 K. [reprint (PDF)]
 
13.  Room Temperature Operation of InTlSb Infrared Photodetectors on GaAs
J.D. Kim, E. Michel, S. Park, J. Xu, S. Javadpour and M. Razeghi
Applied Physics Letters 69 (3)-- August 15, 1996 ...[Visit Journal]
Long-wavelength InTlSb photodetectors operating at room temperature are reported. The photo- detectors were grown on (100) semi-insulating GaAs substrates by low-pressure metalorganic chemical vapor deposition. Photoresponse of InTlSb photodetectors is observed up to 11 µm at room temperature. The maximum responsivity of an In0.96Tl0.04Sb photodetector is about 6.64 V/W at 77 K, corresponding to a detectivity of about 7.64 × 108 cm·Hz½/W. The carrier lifetime in InTlSb photodetectors derived from the stationary photoconductivity is 10–50 ns at 77 K. [reprint (PDF)]
 
13.  Improved performance of quantum cascade lasers via manufacturable quality epitaxial side down mounting process utilizing aluminum nitride heatsinks
A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, C.K.N. Patel
SPIE Conference, San Jose, CA, Vol. 6127, pp. 612702-- January 23, 2006 ...[Visit Journal]
We report substantially improved performance of high power quantum cascade lasers by utilizing epi-side down mounting that provides superior heat dissipation properties. We have obtained CW power output of 450 mW at 20°C from mid-IR QCLs. The improved thermal management achieved with epi-side down mounting has also permitted us to carry out initial lifetime tests on the mid-IR QCLs. No degradation of power output is seen even after over 300 hours of CW operation at 25°C with power output in excess of 300 mW. We believe these improvements should permit incorporation of mid-IR QCLs in reliable instrumentation. [reprint (PDF)]
 
13.  Optical losses of Al-free lasers for λ = 0.808 and 0.98 μm
H. Yi, J. Diaz, B. Lane, and M. Razeghi
Applied Physics Letters 69 (20)-- November 11, 1996 ...[Visit Journal]
In this work, we study the origin of the optical losses in Al‐free InGaAsP/GaAs (λ=0.808 μm) and InGaAs/GaAs/InGaP (λ=0.980 μm) lasers. Theoretical modeling and the experimental results indicate that the scattering of the laser beam by refractive index fluctuation in the alloys is the dominant loss in our lasers, and the loss due to the free‐carrier absorption and scattering by interface roughness are negligible. [reprint (PDF)]
 
13.  Frequency-Shifted Polaron Coupling in Ga0.47In0.53As Heterojunctions
R. J. Nicholas*, L. C. Brunel, S. Huant, K. Karrai, and J. C. Portal† M. A. Brummell M. Razeghi K. Y. Cheng and A. Y. Cho
Phys. Rev. Lett. 55, 883 – 1985-- August 19, 1985 ...[Visit Journal]
Frequency-dependent cyclotron-resonance measurements are reported on Ga0.47In0.53As-InP and Ga0.47In0.53A⁢s−A⁢l0.48In0.52As heterojunctions. Discontinuities in the effective mass occur at two frequencies as a result of resonant polaron coupling with both optic-phonon modes present in the Ga0.47In0.53As alloy. The coupling occurs at the frequencies at the TO phonons, in contrast to measurements on bulk materials. Possible changes in the screening and polarization of the optic-phonon modes are considered. [reprint (PDF)]
 
13.  Reliable High-Power Uncoated Al-free InGaAsP/GaAs Lasers for Cost-Sensitive Optical Communication and Processing Applications
M. Razeghi
SPIE Conference, Dallas, TX, -- November 4, 1997 ...[Visit Journal]
Unlike InP-based systems for long-distance communication applications, GaAs-based optoelectronic systems mostly for local-area network, optical interconnection or optical computing are very cost-sensitive because often these optoelectronic devices constitute most of the cost for these applications and fewer users share the cost. Thus besides technical issues, the processing cost should be addressed in the selection of materials and fabrication methods. We discuss a number of major advantages of Al-free InGaAsP/GaAs lasers for these applications, such as not coating- requirement, low cost, high long-term reliability, high performance. We discuss recent preliminary results of Al- free lasers as a first step toward these optoelectronic applications. [reprint (PDF)]
 
13.  High quantum efficiency mid-wavelength infrared type-II InAs/InAs1-xSbx superlattice photodiodes grown by metal-organic chemical vapor deposition
Donghai Wu , Quentin Durlin, Arash Dehzangi , Yiyun Zhang , and Manijeh Razeghi
Appl. Phys. Lett. 114, 011104-- January 8, 2019 ...[Visit Journal]
We report the growth and characterization of mid-wavelength infrared type-II InAs/InAs1-xSbx superlattice photodiodes on GaSb substrates grown by metal-organic chemical vapor deposition. At 150 K, the 50% cut-off wavelength is 5.0 um, the dark current density is 3.3x10−4 A/cm2 under −20mV bias, and the peak responsivity is 1.76A/W corresponding to a quantum efficiency of 55% without anti-reflection coating. A specific detectivity of 1.2x1011cmHz1/2/W is achieved at 4.0 um under −20mV bias at 150 K. [reprint (PDF)]
 
13.  MOCVD grown β-Ga2O3 metal-oxide-semiconductor field effect transistors on sapphire
Ji-Hyeon Park , Ryan McClintock, Alexandre Jaud, Arash Dehzangi , Manijeh Razeghi
Applied Physics Express 12, 095503-- August 28, 2019 ...[Visit Journal]
We fabricated β-Ga2O3:Si metal-oxide field-effect transistors (MOSFETs) on c-plane sapphire substrates which typically showed maximum drain current of 100 mA·mm−1. β-Ga2O3:Si thin films were realized on c-plane sapphire substrates through a combination of metalorganic chemical vapor deposition and post-annealing. The MOSFET device presented excellent on/off drain current ratio of ∼1011 with very low gate leakage current, sharp pinch off behavior, and a breakdown voltage of 400 V at VG = −40 V. The growth and fabrication of β-Ga2O3:Si MOSFETs on c-plane sapphire is valuable to its demonstration of the great potential for future high-power electronic devices. [reprint (PDF)]
 
13.  High Detectivity InAs Quantum-Dot Infrared Photodetectors Grown on InP by Metalorganic Chemical Vapor Deposition
W. Zhang, H. Lim, M. Taguchi, S. Tsao, B. Movaghar, and M. Razeghi
Applied Physics Letters, 86 (19)-- May 9, 2005 ...[Visit Journal]
We report a high-detectivity InAs quantum-dot infrared photodetector. The InAs quantum dots were grown by self-assembly on InP substrates via low-pressure metal–organic chemical–vapor deposition. Highly uniform quantum dots with a density of 4×1010 cm2 were grown on a GaAs/InP matrix. Photoresponse was observed at temperatures up to 160 K with a peak of 6.4 µm and cutoff of 6.6 µm. Very low dark currents and noise currents were obtained by inserting Al0.48In0.52As current blocking layers. The background-limited performance temperature was 100 K. A detectivity of 1.0×1010 cm·Hz½/W was obtained at 77 K with a bias of –1.1 V. [reprint (PDF)]
 
13.  Sharp/Tuneable UVC Selectivity and Extreme Solar Blindness in Nominally Undoped Ga2O3 MSM Photodetectors Grown by Pulsed Laser Deposition
D. J. Rogers, A. Courtois, F. H. Teherani, V. E. Sandana, P. Bove, X. Arrateig, L. Damé, P. Maso, M. Meftah, W. El Huni, Y. Sama, H. Bouhnane, S. Gautier, A. Ougazzaden, M. Razeghi
Proc. SPIE 11687, Oxide-based Materials and Devices XII, 116872D (24 March 2021); doi: 10.1117/12.2596194 ...[Visit Journal]
Ga2O3 layers were grown on c-sapphire substrates by pulsed laser deposition. Optical transmission spectra were coherent with a bandgap engineering from 4.9 to 6.2 eV controlled via the growth conditions. X-ray diffraction revealed that the films were mainly β-Ga2O3 (monoclinic) with strong (-201) orientation. Metal-Semiconductor-Metal photodetectors based on gold/nickel Inter- Digitated-Transducer structures were fabricated by single-step negative photolithography. 240 nm peak response sensors gave over 2 orders-of-magnitude of separation between dark and light signal with state-of-the-art solar and visible rejection ratios ((I240 : I290) of > 3 x 105 and (I240 : I400) of > 2 x 106) and dark signals of <50 pA (at a bias of -5V). Spectral responsivities showed an exceptionally narrow linewidth (16.5 nm) and peak values exhibited a slightly superlinear increase with applied bias up to a value of 6.5 A/W (i.e. a quantum efficiency of > 3000%) at 20V bias. [reprint (PDF)]
 

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