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
    A 14.6-GHz ECR ion source for atomic physics and materials research with highly charged slow ionsa) (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3078-3083 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 14.6-GHz electron cyclotron resonance ion source has been designed and will be installed at the TU Dresden. Contrary to other ECR sources some features are foreseen for atomic physics experiments to study the source plasma. Beside the description of source construction and computer-aided source control first physical experiments on the source are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Optical characterization of selectively intermixed GaAs/GaAlAs quantum wires by Ga+ masked implantation (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1444-1450 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quantum wires were fabricated by selective intermixing of a GaAs/GaAlAs quantum well through masked Ga+ implantation and rapid thermal annealing. The evolution of the luminescence spectra of the wires with the width of the implantation masks, enabled us to characterize the lateral selectivity of our process as well as the degree of one-dimensional confinement. The lateral extent of the intermixing was estimated at 20 nm giving rise to an important penetration of aluminum into the wires. From numerical simulations of the spatial distribution of implantation-induced damage, it was concluded that some lateral diffusion of the defects occurred during annealing. However it has been possible to assess the confinement energies to be around 4 meV. The linewidth of the wires' emission turned out to increase with decreasing mask size, indicating the presence of some fluctuations of the confining potential along the wires. The roughness of the lateral definition of the wires was evaluated at 20 nm, of the same order of magnitude as the dimension of the intermixed region under the mask. Under these conditions optical excitation spectroscopy failed to detect the different one-dimensional subbands. Finally the potentialities of this method of fabrication of quantum wires are inspected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349555
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Damage generation and annealing in Ga+ implanted GaAs/(Ga,Al)As quantum wells (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4833-4842 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The damage generation and its annealing behavior in GaAs/(Ga,Al)As quantum wells after Ga+ implantation at room temperature is investigated by transmission electron microscopy. Its relations with the disordering of the layered structures is explored by low temperature photoluminescence spectroscopy. We find that at low doses the intermixing is activated during annealing through the diffusion of point defects, while at high doses the disordering is produced by cascade mixing. A strong segregation of the defects in the GaAs layers is observed. During implantation of a GaAs/Ga0.65Al0.35As single quantum well, the GaAs quantum-well layer accumulates damage more rapidly than the Ga0.65Al0.35As barriers. At high dose this leads to a differential amorphization of the two compounds. Using the critical damage energy density model, the amorphization thresholds of GaAs and Ga0.65Al0.35As are estimated around 26 eV/molecule and 960 eV/molecule, respectively, in our conditions of implantation. The influence of barriers in AlAs is studied. AlAs is more resistant to amorphization than Ga0.65Al0.35As and delays the amorphization of the GaAs quantum-well layer. This effect is attributed to the in situ recombination of point defects during irradiation in AlAs material as well as to some intermixing of the layers. After annealing it appears that defects can easily diffuse in Al rich materials but are trapped in GaAs. It is concluded that the ability of AlAs to prevent damage accumulation in GaAs quantum wells and to drain off the defects during annealing can be exploited for device applications. The general trends for an optimized GaAs/GaAlAs quantum well dedicated to mixing applications such as the fabrication of quantum-well wires by masked implantation is finally proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350626
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Mixing of GaAs/(Ga,Al)As interfaces by Ga+ implantation (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1433-1443 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The intermixing of GaAs/(Ga,Al)As heterointerfaces by Ga+ implantation and annealing has been investigated. The damage accumulation in a GaAs/AlAs superlattice turned out to be less rapid than in a GaAs/GaAlAs quantum-well structure. Low-temperature photoluminescence (PL) spectroscopy of a GaAs/AlAs superlattice could be performed for doses as high as 1 × 1016 ions/cm2. The photoluminescence spectra exhibited several emission bands on the high energy side. The number and energy of these blue shifted peaks were found to depend on the implanted dose and as confirmed by secondary ion mass spectrometry, they could be interpreted as the emission of several quantum wells of the superlattice, disordered with different mixing rates. Two regimes were evidenced; while the depth extension of the disordering has been directly related to the post-implantation defects distribution in the high dose regime, some diffusion of these defects during annealing has been pointed out in the low dose regime. Cross-sectional transmission electron microscopy observations have confirmed the influence of the structure of the implanted sample on damage accumulation. Moreover, the decrease of the PL intensity after annealing could be related to the presence of extended residual defects in the implanted layers. The study of the influence of annealing time at 760 °C, has shown that the photoluminescence intensity can be progressively recovered, while the intermixing saturates rapidly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349554
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Optimized selective mixing of a GaAs/GaAlAs quantum well for the fabrication of quantum wires (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5012-5015 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the structure of a GaAs/GaAlAs quantum well, which can promote strong mixing rates upon high-dose implantation, with good recovery of the electronic properties after annealing. This structure is employed to fabricate quantum-well wires by Ga+ masked implantation. Low-temperature photoluminescence measurements reveal large lateral modulations of the effective band gap ((approximately-greater-than)178 meV), and small lateral interdiffusion lengths (10 nm). A simple calculation shows that one-dimensional quantization energies between 11 and 20 meV can be expected in these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350601
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A 14.6-GHz ECR ion source for atomic physics and materials research with highly charged slow ions (abstract) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2850-2850 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 14.6-GHz electron cyclotron resonance ion source has been designed and will be installed at the TU Dresden. Contrary to other ECR sources some features are foreseen for atomic physics experiments to study the source plasma. Beside the description of source construction and computer-aided source control first physical experiments on the source are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143823
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Perturbations, inhibition, and promotion of ultraviolet surface photochemistry: CH3 Br on Br/Ni(111) (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2004-2014 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The inhibition and perturbations of surface photochemistry, due to the coupling of the excited state to the surface, are discussed as it pertains to CH3 Br adsorbed on nickel. Photofragmentation of CH3 Br was observed on a brominated Ni(111) surface, with the fragmentation process being strongly perturbed at low coverages. The perturbations are attributed to charge transfer processes. Direct photofragmentation was observed as well as a surface specific dissociative electron attachment channel. Cross section values are reported for fragmentation at 193 and 248 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458033
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Laser Doppler measurement of turbulence parameters in a two-dimensional plane wall jet (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 3116-3129 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A computer-controlled data acquisition system has been designed and constructed to automate measurement of turbulent velocity correlations in a two-dimensional turbulent wall jet. Measurements are made with a single component laser Doppler velocimeter system in a flow of air on a flat plate with stagnant surroundings. Measurements of a number of turbulence parameters have been completed and compared with existing hot-wire data. The measurements are made at two downstream locations at a Reynolds number, based on slot width, of 14 000. Earlier hot-wire data for a two-dimensional turbulent wall jet in stagnant surroundings show much scatter in the outer region where local turbulence intensities range from 40% to 70%. The laser Doppler velocimeter gives repeatable values and eliminates the bias in hot-wire measurements due to reversing flow and errors in corrections for high turbulence effects. The measured turbulent normal stresses are somewhat higher than those previously reported throughout the flow field. The turbulent shear stress is in good agreement with previous hot-wire results near the wall. Hot wires are shown to indicate low values of the Reynolds stress in the turbulent outer regions where they are affected by strong flow reversals. The new measurements agree well with predictions based on momentum integral methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868136
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    High-resolution x-ray spectrometer for an electron beam ion trap (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2338-2342 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-throughput von Hámos-type Bragg crystal spectrometer is described that is operated with the Livermore electron beam ion trap. The spectrometer is employed to measure high-resolution x-ray spectra from highly charged heliumlike and neonlike ions. Data from heliumlike Ti20+ and Fe24+ and from neonlike Au69+ are presented to demonstrate the utility of the new instrument.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141361
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Growth Factors Proto-Oncogenes and Plasticity of the Cardiac Phenotype (1991)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 53 (1991), S. 179-200 
    Details
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ph.53.030191.001143
    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...