Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photocurrent available from a p-i-n solar cell can be increased by the addition of quantum wells (QWs) to the undoped region. At the same time the QWs reduce the open-circuit voltage by introducing areas of lower band gap where recombination is enhanced. This increase in recombination should be as small as possible for the most favorable effect on the photovoltaic efficiency of the device. Theoretical considerations indicate that nonradiative recombination, which is the dominant loss mechanism in AlxGa1−xAs/GaAs QW structures, may be reduced by positioning the QWs away from the point where the electron-hole product is a maximum. For p-i-n diodes, where recombination is greatest at or near the center of the space charge region, this means locating the QWs closer to the doped regions. Spectral response should not be affected so long as the QWs are still located within the field bearing region. Thus, improved photovoltaic performance may be expected through strategic location of the QWs. We report on measurements on a series of Al0.36Ga0.64As p-i-n photodiodes, three of which contained a single 87 Å GaAs QW within the i region, and one which was a control sample with no QW. The three QW samples were grown with the QW located nearer to the p-doped layer, centrally, and nearer to the n-doped layer, respectively. Spectral response measurements confirm that for good quality samples photocurrent is independent of QW location within the depleted region. Contrary to expectations, the dark current is highest for the sample with the QW located closer to the n region. We analyze these results in terms of structure and doping profile, and compare them with the predictions of a self-consistent model. The observed behavior is attributed to a relatively high unintentional background doping in the intrinsic region. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 154-159 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Arrays of 12 flush-mounted Langmuir probes have been installed in both the upper and lower outboard divertor plates of TdeV (Tokamak de Varennes). Measurements of electron temperature and density are obtained using a novel method of analysis which assumes that charge collection is dominated by the finite size of the electrostatic sheath. The technique is validated by comparing measurements from a cylindrical and a flush probe which are operated simultaneously in the same plasma. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1862-1867 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a simple method of collecting the thermal derivative spectra of solids. In this method, a sample's reflectance is measured at two specific temperatures and the thermal difference of the material's reflectance is calculated. By digitally averaging these differences, we obtain spectra equivalent to thermal modulation spectra. Since this is not a modulation technique we have named it thermal difference spectroscopy. Using the thermal difference spectrometer we have achieved a base line noise level in the normalized thermal difference reflectance spectrum (ΔR/R) of approximately 5×10−5. To demonstrate the technique's utility as a truly noncontact derivative spectroscopy we have collected thermal difference spectra of both thin-film and bulk samples.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Insertion of an LC single-stage notch filter (of the shunt variety) between the output of a quadrupole mass spectrometer and a fast current amplifier greatly attenuates the rf noise typically present on the signal output. The 2.5-MHz rf was significantly reduced with negligible interference of the 1-μs resolved time of flight (TOF) work. Also presented is the fast current amplifier design.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 3906-3915 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The purpose of this paper is to provide definitions for, and proofs of, the asymptotic formulas given by Edmonds, which relate the 3j and 6j symbols to rotation matrices. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 35 (1994), S. 2701-2718 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The consequences of the assumption of invariance of a spinor theory under local automorphism transformations of the Clifford algebra basis elements are explored. This invariance is equivalent to allowing the orthonormal basis spinors of the spinor space to be chosen arbitrarily at each point in space–time and is analogous to the situation in general relativity where the orthonormal basis vectors of the tangent space are allowed to be chosen arbitrarily at each point in space–time. This invariance then dictates that the Clifford algebra generators be functions of space–time and is implemented by introducing new fields, the drehbeins ("spin legs''), which are somewhat akin to the vielbeins introduced in general relativity to invoke the concept of local Lorentz invariance. However, in contrast to general relativity, the covariant derivatives of the Clifford algebra generators do not vanish. The dynamical variables of the theory are then the spinors, the gauge fields of the automorphism group, and the drehbeins. The invariant Lagrangian density and the concomitant field equations for this theory are discussed. Interestingly, the "kinetic'' Lagrangian density term for the drehbein fields induces a gauge invariant mass term for the gauge fields. This constitutes a new mass generation mechanism, of different character and complementary to the familiar Higgs mechanism. Although the idea of local automorphism invariance is a natural generalization of the principle of equivalence, herein attention is restricted to the case of nondynamic flat space–time.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thin capping layer of annealed GaAs (∼210 A(ring)) grown at low temperature (LT-GaAs) can effectively block incident ions from penetrating into the growth substrate. Ion-bombarded, multiple quantum well structures capped by an annealed LT-GaAs layer show a dramatic improvement in the photoluminescence, compared to samples capped with "normal'' GaAs. The improvement appears to be correlated with the microstructures of the LT-GaAs, since the improvement is particularly notable for samples annealed at 600 °C. This improvement in low energy ion-induced damage is primarily the result of the reduced channeling of ions through the LT-GaAs layer. These results suggest a potential application of LT-GaAs in reducing ion damage and underscore the importance of the microstructure of arsenic precipitates in LT-GaAs layers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 58-60 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the influence of concurrent above-band-gap laser illumination on the damage profile of GaAs/AlGaAs heterostructures subject to low energy (sub-keV) Ar+ ion bombardment. A dramatic change in damage profile was observed for these samples, compared with those that were not laser illuminated, and the degradation increases with the illuminated power intensity. Below-band-gap illumination results in a minimal increase in damage profile. Such results indicate the possibility of radiation-enhanced diffusion of defects, and may explain the observed high defect diffusivity at room temperature. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2335-2337 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report reflection high-energy electron diffraction oscillations during molecular beam epitaxy of GaAs at temperatures as low as 125 °C using As2 as the arsenic source. At a substrate temperature of 200 °C, the As:Ga ratio is shown to be the critical parameter which determines the amplitude of these oscillations. The largest amplitude oscillations are obtained when the As:Ga ratio is about 1:1. In order for these oscillations to occur, the arriving atoms must have some surface mobility. Monte Carlo simulations show that step density oscillations with a period corresponding to one monolayer are expected if the incident atoms are allowed to move as little as one lattice site upon arrival at the surface. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1558-1560 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surface charging effects on etching profiles during silicon etching in a nonuniform plasma were investigated by scanning electron micrographs and plasma potential measurements. The distortion in ion trajectories caused by the surface charging was calculated by an ion lens simulator. A tilt in the etching profile was found in holes and trenches near a large etched area when an insulating mask such as photoresist or silicon dioxide was used. Ion trajectory calculations showed that this profile tilt was caused by the local electric field resulting from the potential difference between the charged mask surface and the electrically grounded silicon substrate. This profile result agrees well with gate oxide damage results which were also successfully explained by surface charging.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...