Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Coherent millimeter-wave generation by heterodyne conversion in low-temperature-grown GaAs photoconductors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 1480-1484 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analysis has been carried out of optical heterodyne conversion with an interdigitated-electrode photomixer made from low-temperature-grown (LTG) GaAs and pumped by two continuous-wave, frequency-offset pump lasers. The analytic prediction is in excellent agreement with the experimental results obtained recently on a photomixer having 1.0-μm-wide electrodes and gaps. The analysis predicts that a superior photomixer having 0.2-μm-wide electrodes and gaps would have a temperature-limited conversion efficiency of 2.0% at a low difference frequency, 1.6% at 94 GHz, and 0.5% at 300 GHz when connected to a broadband 100 Ω load resistance and pumped at hν=2.0 eV by a total optical power of 50 mW. The predicted 3-dB bandwidth (193 GHz) of this photomixer is limited by both the electron-hole recombination time (0.6 ps) of the LTG-GaAs material and the RC time constant (0.5 ps) of the photomixer circuit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353222
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A novel mutation in the 2B domain of keratin 2e causing ichthyosis bullosa of Siemens (2000)
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 25 (2000), S. 0 
    Details
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Ichthyosis bullosa of Siemens (IBS; MIM: 146800) is an autosomal dominant disorder of keratinization characterized by epidermolytic hyperkeratosis without erythroderma. The clinical features are less marked than those of bullous congenital ichthyosiform erythroderma with relatively mild hyperkeratosis usually limited to the skin flexures. Mutations in the epithelial cytokeratin 2e (K2e), which is expressed in a differentiation-specific fashion in the upper spinous and granular layers of the epidermis, have been shown to cause IBS. We detected a novel mutation in a three generation kindred with IBS (1448T→A) within exon 7 of the KRT2E gene. This is predictive of an I483N substitution in the 2B domain of K2e. This extends the range of mutations reported to date and illustrates the usefulness of molecular genetics in the diagnosis of this disorder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2230.2000.00728.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Panniculitis complicating gallstone pancreatitis with subsequent resolution after therapeutic endoscopic retrograde cholangiopancreatography (2000)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 143 (2000), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2000.03921.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Breakdown of crystallinity in low-temperature-grown GaAs layers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2153-2155 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic study of the change in structural quality of as-grown GaAs layers deposited at temperatures between 180 and 210 °C by molecular beam epitaxy was performed using transmission electron microscopy, double-crystal x-ray rocking curves, and particle-induced x-ray emission. We found that the crystal quality was correlated strongly with growth temperature near 200 °C. The lattice parameter and the amount of As incorporated in the layer were observed to increase at lower growth temperatures. After exceeding a certain growth-temperature-dependent layer thickness, large densities of pyramidal-type defects are formed, which at lowest growth temperature result in the breakdown of crystallinity and in columnar polycrystalline growth. The lattice expansion is ascribed to the excess As in the layers. The mechanisms of breakdown of crystallinity are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104990
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Coherent detection with a GaAs/AlGaAs multiple quantum well structure (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1513-1515 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A GaAs/AlGaAs multiple quantum well (MQW) structure has been investigated as a coherent detector using a CO2-laser local oscillator (LO). At an operating temperature of 77 K, an LO power of 10 mW, an LO wavelength of 10.2 μm, and a bias voltage of 2.0 V, a 150-μm-diam detector displayed an external quantum efficiency η0 of 11% and a 3-dB electrical bandwidth BIF of 1.5 GHz. Under the same conditions the noise-equivalent power density (NEPHET/Δf) at an intermediate frequency of 1.5 GHz was 5.5×10−19 W/Hz, which is within 50% of the photon-noise limit for this detector. A 75-μm-diam detector with a lower-capacitance bond wire was found to have a BIF of 8 GHz and an NEPHET/Δf of 4.1×10−19 W/Hz with only 2.5 mW of LO power. The photoelectron lifetime in the MQW structure at 77 K was estimated to be 2.5 ps corresponding to an intrinsic detector bandwidth of 64 GHz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108624
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Subpicosecond carrier lifetime in GaAs grown by molecular beam epitaxy at low temperatures (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3276-3278 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial GaAs grown by molecular beam epitaxy (MBE) at low substrate temperatures is observed to have a significantly shorter carrier lifetime than GaAs grown at normal substrate temperatures. Using femtosecond time-resolved-reflectance techniques, a sub-picosecond (〈0.4 ps) carrier lifetime has been measured for GaAs grown by MBE at ∼200°C and annealed at 600 °C. With the same material as a photoconductive switch we have measured electrical pulses with a full-width at half-maximum of 0.6 ps using the technique of electro-optic sampling. Good responsivity for a photoconductive switch is observed, corresponding to a mobility of the photoexcited carriers of ∼120–150 cm2/V s. GaAs grown by MBE at 200 °C and annealed at 600 °C is also semi-insulating, which results in a low dark current in the switch application. The combination of fast recombination lifetime, high carrier mobility, and high resistivity makes this material ideal for a number of subpicosecond photoconductive applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105729
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Milliwatt output levels and superquadratic bias dependence in a low-temperature-grown GaAs photomixer (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 3311-3313 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A cw output power up to 0.8 mW is obtained from a low-temperature-grown (LTG) GaAs, 0.3 μm gap, interdigitated-electrode photomixer operating at room temperature and pumped by two modes of a Ti:Al2O3 laser separated in frequency by 0.2 GHz. The output power and associated optical-to-electrical conversion efficiency of 1% represent more than a sixfold increase over previous LTG-GaAs photomixer results obtained at room temperature. A separate LTG-GaAs photomixer having 0.6 μm gaps generated up to 0.1 mW at room temperature and up to 4 mW at 77 K. Low-temperature operation is beneficial because it reduces the possibility of thermal burnout and it accentuates a nearly quartic dependence of output power on bias voltage at high bias. The quartic dependence is explained by space-charge effects which result from the application of a very high electric field in the presence of recombination-limited transport. These conditions yield a photocurrent-voltage characteristic that is very similar in form to the well-known Mott–Gurney square-law current in trap-free solids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111289
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    375-GHz-bandwidth photoconductive detector (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1984-1986 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the development of a new, integrable photoconductive detector, based on low-temperature-grown GaAs, that has a response time of 1.2 ps and a 3-dB bandwidth of 375 GHz. The responsivity is 0.1 A/W. Signal amplitudes up to 6 V can be produced with virtually no degradation in response time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106157
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Measurements of optical-heterodyne conversion in low-temperature-grown GaAs (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1206-1208 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A low-temperature-grown GaAs interdigitated-electrode photomixer is used to generate coherent power at microwave frequencies. An output power of 200 μW (−7 dBm) is generated by pumping the photomixer with two 70-mW modes of a Ti:Al2O3 laser, separated in frequency by 200 MHz. This represents an optical-to-microwave conversion efficiency of 0.14%, which is within 50% of a prediction based on optical-heterodyne theory. When two lasers are used and the frequency of one is tuned with respect to the other, the output frequency of the photomixer increases smoothly and the output power is nearly constant up to 20 GHz. At higher frequencies the power decays because of parasitic capacitance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108735
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Prediction by computerised tomography of distance from skin to epidural space during thoracic epidural insertion (2002)
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 57 (2002), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary In this single group observational study on 29 patients, we describe a technique that predicts the depth of the epidural space, calculated from the routine pre-operative chest computerised tomography (CT) scan using Pythagorean triangle trigonometry. We also compared the CT-derived depth of the epidural space with the actual depth of needle insertion. The CT-derived and the actual depths of the epidural space were highly correlated (r = 0.88, R2 = 0.78, p 〈 0.0001). The mean (95% CI) difference between CT-derived and actual depths was 0.26 (0.03–0.49) cm. Thus, the CT-derived depth tends to be greater than the actual depth by between 0.03 and 0.49 cm. There were no associations between either the CT-derived or the actual depth of the epidural space and age, weight, height or body mass index.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2044.2002.02572_4.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...