Electronic Material Properties - und Geowissenschaften ...

Recommendations

Info

∆ = 0 − exhibiting dominance of space charge effects at low barriers. At low voltages up to 0.1 V all I-V-characteristics show an Ohmic-like j ≈ V dependence. This Ohmic regime is followed by an exponential increase of the current density with the voltage up to the built-in voltage VBI = 0.81 eV corresponding to the difference in the workfunctions of the electrodes. This increase can be attributed to a diffusive charge carrier transport against the weakened electric field in the organic material. If a high injection barrier is present, the following current-density increase is also exponential due to the barrier modification by the electric field at the interface. After all, when the injection barrier at the injecting electrode falls below ∆ crit the calcium contact can supply more charge carriers than the bulk of the organic semiconductor can transport. That is why all the I-V-characteristics end up in the space charge limited regime. In the case of high injection barriers the approximate analytic consideration results in the I-V-characteristic of the system which reads ⎛ eV ⎞ − exp⎜− ⎟ −1 V + V ⎛ ∆ ⎞ BI eff exp⎜ ⎟ ⎝ kT j = −eµ ⎠ s N ⎜ − ⎟ , (2) L ⎝ kT ⎠ ⎛ e( V + VBI ) ⎞ exp⎜− ⎟ −1 ⎝ kT ⎠ where µ s is the mobility of electrons in the insulator and the modified barrier equals − − ∆eff = ∆ + eε lTFFs ( −L / 2) . The agreement of this formula with numerical calculations is perfect for reverse and forward bias until the space charge effects become dominant. Fig. 1: I-V-characteristics for an organic layer with thickness L = 100 nm contacted with a calcium electrode at x = -L/2 and a magnesium electrode at x = L/2. The injection barrier of the calcium electrode is varied from 0 eV to 0.4 eV with an increment of 0.1 eV. Finally, the presented model is capable of describing a metal/insulator/metal device in the injection limited as well as in the space charge limited regime and reveals conditions of the crossover from one regime to another. - 98 -
Penetration of an external magnetic field into a multistrip superconductor/soft-magnet heterostructure S.V. Yampolskii, Y.A. Genenko, H. Rauh Heterostructures made up of superconductor (SC) and soft-magnet (SM) constituents are being studied extensively because of their potential for improving the performance of SCs. The use of SMs for such structures offers the possibility to alter the pinning of magnetic vortices in the SC constituents through easy tuning of the intrinsic magnetic moment of the SM constituents. Furthermore, the large permeability of SMs allows to improve the critical parameters of SC wires and strips by shielding the transport current self-induced magnetic field as well as an externally imposed magnetic field. As is known from previous work, the critical current of a periodic structure of SC strips separated by slits is markedly enhanced compared with that of an isolated SC strip. Here, therefore, we study how filling the slits with SM strips controls the penetration of magnetic flux into such a heterostructure. To this end, we consider a periodic array of infinitely extended type-II SC and SM strips of respective widths wS and M , i.e. period , and thickness d, oriented parallel to the x-y-plane of a cartesian coordinate system x, y, z and exposed to a transverse external magnetic field H , as shown in Fig. 1. The SC constituents shall be devoid of magnetic flux penetrated from their infinitely far ends; the SM constituents shall be fully described by the relative magnetic permeability w w=w S+wM 0 µ . Assuming, in addition, d/w
Page 1:
ANNUAL REPORT 2 0 0 6 FACULTY OF MA
Page 4 and 5:
Annual Report 2006 Faculty 11 Mater
Page 6 and 7:
Preface The year 2006 of the Depart
Page 8 and 9:
difference of numerical and analyti
Page 10 and 11:
Institute of Materials Science Phys
Page 12 and 13:
Research Projects Bulk Amorphous Al
Page 14 and 15:
el Dsoki, C.; Landersheim, V. ; Kau
Page 16 and 17:
Das, J.; Kim, K. B.; Xu, W.; Wei, B
Page 18 and 19:
Staff Members Head Prof. Dr. Jürge
Page 20 and 21:
Zhou L.; Rixecker G.; Aldinger F.;
Page 22 and 23:
concerned with the synthesis and ch
Page 24 and 25:
Publications Fleissner, A.; Schmid,
Page 26 and 27:
• Surface analysis The UHV-surfac
Page 28 and 29:
T. Mayer, U. Weiler, E. Mankel and
Page 30 and 31:
Thin films The Thin Film division w
Page 32 and 33:
Berky, W.; Gottschalk, S.; Elliman,
Page 34 and 35:
Guest Scientists Research Projects
Page 36 and 37:
Hesse, S.; Zimmermann, J.; von Segg
Page 38 and 39:
Structure Research The research in
Page 40 and 41:
Research Projects Functional Advanc
Page 42 and 43:
Dincer, I.; Elerman, Y.; Elmali, A;
Page 44 and 45:
hexakis(imidazole)nickel(II)bis(for
Page 46 and 47:
Chemical Analytics The chemical ana
Page 48 and 49:
Collaborations The above mentioned
Page 50 and 51: Hoffmann, P.; Non-Invasive Identifi
Page 52 and 53: Ferroelectrics For this class of ma
Page 54 and 55: Materials Modelling The research ac
Page 56 and 57: Materials for Renewable Energies In
Page 58 and 59: Joint Research Laboratory Nanomater
Page 60 and 61: Collaborative Research Center (SFB)
Page 62 and 63: B7 P.I.: Prof. H. v. Seggern / Dr.
Page 64 and 65: The glass transition temperature (T
Page 66 and 67: transition allows to investigate at
Page 68 and 69: Relative density 1.00 0.95 0.90 0.8
Page 70 and 71: Fig. 2 shows the time dependencies
Page 72 and 73: Dielectric interface trap engineeri
Page 74 and 75: ∆V C q th eff 12 −2 p ( VGS = 0
Page 76 and 77: Fig. 3: Schematic of the photovolta
Page 78 and 79: synthesis and analysis of interface
Page 80 and 81: Fig. 2: Resistivity vs temperature
Page 82 and 83: Fig. 2: X-ray appearance near-edge
Page 84 and 85: Capacity [mAhg -1 ] 700 600 500 400
Page 86 and 87: Texture investigations and field em
Page 88 and 89: screening effects. Gold coating of
Page 90 and 91: Figure 2 shows a selected region of
Page 92 and 93: The spectrum shows that apart from
Page 94 and 95: The effect of crystallinity on the
Page 96 and 97: Electrochemical investigation and c
Page 98 and 99: This phenomenon can be understood c
Page 102 and 103: constituents. The requirement of va
Page 104 and 105: In order to assess the influence of
Page 106 and 107: In this study, we have therefore de
Page 108 and 109: Fig. 1: Proposed models for a) Pt,
Page 110 and 111: Synthesis of oxide-polymer nanocomp
Page 112 and 113: Diploma Theses Böhme, Mario; Herst
Page 114 and 115: Sperling, Sebastian; Untersuchungen
Page 116 and 117: Institute of Applied Geosiences Phy
Page 118 and 119: Research Projects Geomorphology and
Page 120 and 121: Engineering Geology Engineering Geo
Page 122 and 123: Investigation of a Doline in NE-Hes
Page 124 and 125: Applied Sedimentology Sedimentary r
Page 126 and 127: econstruction.(Diploma thesis in co
Page 128 and 129: Darmstadt University of Technology
Page 130 and 131: Geomaterials Science Geomaterial Sc
Page 132 and 133: Gregori, G.; Kleebe H.-J.; Sorarù,
Page 134 and 135: Hessische Industriemüll GmbH). Due
Page 136 and 137: Technical Personnel Josef Kolb, Dip
Page 138 and 139: Research Projects Environmental sca
Page 140 and 141: Fig. 1: Aerial photo of the Lake Li
Page 142 and 143: Lithological Map of the Japanese Ar
Page 144 and 145: tower stripping, and therefore much
Page 146 and 147: Diffusion and reaction in micro- an
Page 148 and 149: Rift dynamics, uplift and climate c
Page 150 and 151:
Geology, land use change and erosio
Page 152 and 153:
nearly half a century has been perf
Page 154 and 155:
The Effect of LiF Addition on the S
Page 156 and 157:
In case of the undoped sintered B6O
Page 158 and 159:
Microstructures in Omphacite and Ot
Page 160 and 161:
Modelling phase-assemblage diagrams
Page 162 and 163:
As an example, Fig. 2 shows the che
Page 164:
MATERIALS SCIENCE Physical Metallur
show all

Electronic Material Properties - und Geowissenschaften ...

Create successful ePaper yourself

Delete template?

Save as template?