Browsing by Author "Wu, Jiun-Ji"

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Probing Capacitive Coupling and Collective Transport in PbSe Quantum-Dot Arrays Using Scanning Tunneling Spectroscopy
(2009-05-07)
Ou, Yi-Ching
;
Wu, Jiun-Ji
;
Fang, Jiye
;
Jian, Wen-Bin
;
電子物理學系
Semiconductor quantum dots with diameters of several to tens of nanometers have been largely synthesized through colloidal techniques for nanoscience exploration of quantum confinement, Coulomb staircase, and artificial-atom states in individual quantum dots and self-assembling growth behavior. Although charge transport of three-dimensional quantum dot arrays has been attempted for study on the micron scale, the electrical properties of a nanoscale array, self-assembled from a single quantum dot through a bottom-up procedure, have not been explored yet. We control growth parameters to self-assemble different sizes of PbSe quantum-dot arrays on flat gold surface for scanning tunneling spectroscopy measurements. The current-voltage curves of the arrays are analyzed using a double-barrier tunnel junction model to acquire the shunt capacitance between the array and the gold substrate. The increment of this capacitance is small as the particle number increases extremely from 1 to 40. Thus the array cannot be taken as a simple semiconductor island. We apply collective transport theory to exploration of electron tunneling and capacitive coupling between PbSe quantum dots in the array.