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  • 1
    Digitale Medien
    Digitale Medien
    Stable nanostructuring of ultrathin porous silicon films by scanning tunneling microscopy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2948-2953 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The capability of producing electronically induced modifications in ultrathin (∼20 nm) light-emitting porous silicon (PS) films by use of a scanning tunneling microscope (STM) operated in a high-vacuum environment is demonstrated. Upon increasing the tunnel current to 2 nA and the tunnel voltage beyond a threshold value of ∼7 V, structures 20–50 nm in width can be created to any desired pattern. These nanopatterns are stable at least for four days at room temperature. Experiments with both voltage polarities but equal power densities reveal that these structures can only be induced by directing the intense electron beam provided by the STM tip towards the sample surface, excluding pure thermal effects for the layer modifying process. These observations can be well explained by a model which includes a local increase in the density of defect states in deep-layer regions of the PS layer, which might be accompanied by a local quenching of the photo- or electroluminescence activity. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.361291
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  • 2
    Digitale Medien
    Digitale Medien
    Modeling of broad beam ion sources : Proceedings of the 7th international conference on ion sources (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1147-1149 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Our approach to ion beam modeling breaks down the complex interplay of competing elementary processes into a series of independent consecutive steps. Thus, both in methodological development and computational modeling, the main effort can be directed towards the processes which are of greatest relevance in the context given. Moreover, employment of the special software available allows for comprehensive and efficient optimization of multigrid ion sources for low ion beam divergence and long lifetime, even in a personal computer environment. Here, for our Kaufman-type two-grid ion source RR-ISQ 76 some ion beam characteristics in their dependence on geometrical two-grid configuration are calculated and discussed, first of all in terms of shape and area of the plasma sheath. These dependencies are used to optimize this particular ion source for a low beam divergence. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1148652
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  • 3
    Digitale Medien
    Digitale Medien
    Effects of aperture displacement in broad-beam ion extraction systems : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 928-930 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Low-energy broad-beam ion sources cover a wide range of applications. Geometrical perturbations of the axial-symmetric extraction channels by off-axis shifts of the accelerator grid holes give rise to an ion beamlet tilt which under certain conditions is dependent on the beamlet current. In this study, the characteristics of the beamlet deflection are presented which were obtained by a three-dimensional trajectory simulation. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1428785
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  • 4
    Digitale Medien
    Digitale Medien
    Broad-beam modeling and experiments for electric spacecraft propulsion : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 732-734 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: At IOM Leipzig, we developed an efficient grid erosion simulation code. In our approach to ion beam extraction and grid erosion occurring in a multi-grid multi-aperture ion thruster we break down the complex interplay of pertinent elementary processes into consecutive steps. On the basis of ion optical and short-time grid-erosion measurements on a small broad-beam ion source, a comprehensive experimental validation of this code has been done. The good agreement between measured and simulated data furnishes confidence in the methodology. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150277
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  • 5
    Digitale Medien
    Digitale Medien
    Determination of nanometer structures and surface roughness of polished Si wafers by scanning tunneling microscopy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4273-4281 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Roughness and general surface topography of polished Si wafers were systematically studied on an angstrom to nanometer scale by scanning tunneling microscopy (STM). Evaluation of a large number of STM images by using a simple classification scheme assures statistically relevant results without the disadvantages and loss of information connected with averaging the rms roughness or similar methods. For the flat parts of the surface, a rms roughness of 1.2–1.8 A(ring) is found, comparable to that derived from light scattering and diffraction measurements on similar surfaces. Significant amounts of the surfaces were found to exhibit more pronounced structures, contrasting results of other techniques. The reliability and applicability of STM measurements on technical surfaces, on an angstrom to nanometer scale, is discussed in the light of these results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.348399
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  • 6
    Digitale Medien
    Digitale Medien
    Approximation of the plasma inhomogeneity by broad-beam measurements and simulation : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 678-680 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In broad-beam ion sources an inhomogeneous plasma distribution has a strong effect on both the maximum extractable ion current and the broad-beam profile. An approximate plasma distribution function is determined by fitting calculated accelerator-grid currents to corresponding experimental data, thus efficiently replacing complicated and expensive plasma probe measurements. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150258
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  • 7
    Digitale Medien
    Digitale Medien
    Determination of Calcium or Zinc Additives in Lubricating Oils and Concentrates (1957)
    s.l. : American Chemical Society
    Analytical chemistry 29 (1957), S. 1223-1223 
    Details
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ac60128a036
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  • 8
    Digitale Medien
    Digitale Medien
    Writing electronic nanometer structures into porous Si films by scanning tunneling microscopy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2253-2255 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Under conditions of increased tunnel current and voltage, with the electron flow directed towards the sample, nanometer-scale structures have been written into ultrathin (∼20 nm) light-emitting porous silicon (PS) films using scanning tunneling microscopy in a high-vacuum environment. For the writing process, a threshold voltage of ∼4.5 V is observed and the resulting dimensions range between 20 and 50 nm. Depending on the writing parameters, the modified regions relax or remain stable during the observation time of several days at room temperature. These results can be assigned, in the first case, to a disruption of a small number of bonds, followed by reconfiguration, and a charging of dangling bond sites, followed by carrier release, in near surface regions. In the latter case, the creation of time-stable defect states within the PS layer is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.111635
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  • 9
    Digitale Medien
    Digitale Medien
    Correlation of surface morphology with luminescence of porous Si films by scanning tunneling microscopy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1365-1367 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The evolution of visible photoluminescence is demonstrated by measuring the surface morphology of thin (∼20 nm) electrochemically etched porous silicon (PS) films with scanning tunneling microscopy (STM). Using low current densities, three sorts of samples were prepared under different conditions: In the dark (A), under illumination with ultraviolet (UV) light (B), and in the dark followed by a postphotochemical treatment (C). Upon UV light excitation, type A samples do not emit visible light, while samples of type B and C show weak and efficient photoluminescence in the visible range, respectively. STM imaging of these PS layers reveals a considerable decrease in the lateral dimensions of the surface features from approximately 10 nm (type A) to roughly 2 nm (type C), in accordance with the quantum confinement approach in describing the luminescence properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.111936
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  • 10
    Digitale Medien
    Digitale Medien
    Writing electronically active nanometer-scale structures with a scanning tunneling microscope (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2136-2138 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A scanning tunneling microscope (STM) is used to locally modify p-n junctions on a scale of a few tens of nanometers. The p-n junction is composed of a phosphorus-doped, hydrogenated amorphous Si [a-Si:H(P)] layer deposited on heavily doped p-type crystalline Si(111). Under conditions of high current densities, with the p-n junction biased in forward direction, the a-Si:H layer is structurally changed leading to a decrease of the junction barrier height. The resulting exponential increase of hole injection into the modified amorphous layer leads to electronically active structures. They are detected by STM owing to their differing electronic properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.106104
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