Tunneling transport

The electron transport properties described earlier markedly differ when the particles are organized on the substrate. When particles are isolated on the substrate, the well-known Coulomb blockade behavior is observed. When particles are arranged in a close-packed hexagonal network, the electron tunneling transport between two adjacent particles competes with that of particle-substrate. This is enhanced when the number of layers made of particles increases and they form a FCC structure. Then ohmic behavior dominates, with the number of neighbor particles increasing. In the FCC structure, a direct electron tunneling process from the tip to the substrate occurs via an electrical percolation process. Hence a micro-crystal made of nanoparticles acts as a metal. 

Hettler MH, Wenzel W, Wegewijs MR, Schoeller H (2003) Current collapse in tunneling transport through benzene. Phys Rev Lett 90(7) 076805... 

Fig. 2.13.1. Freeze drying tunnel plant. Upper part in front monorail of the transport system. In the tunnel transport rail for the carrier with trays. In the tunnel heated shelves in between which the carrier with trays is moved. When the carrier is position, the trays are lowereed on to the shelves by lowering the carrier (System CQC , ALD Vacuum Technologies GmbH, D-63526 Erlensee).

Fig. 4. Ground states in the strong pinning regime characterized by the integer number n°. The wavy lines show an excitation from one ground state forming an in-stanton configuration which could be a mechanism for quantum tunneling transport at low temperatures [35, 33],...

The ratio Vo/B determines the transition from coherent diffusive propagation of wavefunctions (delocalized states) to the trapping of wavefunctions in random potential fluctuations (localized states). If I > Vo, then the electronic states are extended with large mean free path. By tuning the ratio Vq/B, it is possible to have a continuous transition from extended to localized states in 3D systems, with a critical value for Vq/B. Above this critical value, wave-functions fall off exponentially from site to site and the delocalized states cannot exist any more in the system. The states in band tails are the first to get localized, since these rapidly lose the ability for resonant tunnel transport as the randomness of the disorder potential increases. If Vq/B is just below the critical value, then delocalized states at the band center and localized states in the band tails could coexist. 

Figure 6.18 Results from junction-recovery measurements on Sn02/Ti02/Au diodes. The electron drift mobility and the mobility-lifetime product are determined for various injection conditions and forward bias. The electron mobility is found to increase with increasing injection level, while the mobility-lifetime product remains approximately constant. These findings can be consistently explained in a transport model based on trap filling and a transport-limited recombination mechanism. An alternative explanation can, however, also be based on a tunnelling transport model (Konenkamp, 2000a).

Cataldo, D.A., Van Voris, P., Ligotke, M.W., Fellow, R.J., McVeety, B.D., Li, S.W., Bolton, H., Jr., and Frederickson, J.K., Evaluate and characterize mechanisms controlling transport, fate and effects of army smokes in an aerosol wind tunnel transport, transformations, fate and terrestrial ecotoxicological effects of fog oil obscurant smokes. Report Number AD-A20414, Pacilic Northwest Laboratory, Richland, Washington, 1989. 

Tunneling Transport The Line Shape of Conductance Peaks... 

Stop tunnel transport if transport pressure gets too high. 

T. Dimopoulos Spin polarised tunnel transport in magnetic tunnel junctions The role of metal/oxide interfaces in the tunnel process. Ph.D. Thesis (University Louis Pasteur, Strasbourg 2002)... 

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