H. -O. Müller | Searcharxiv

arXiv1996

Coulomb blockade threshold in inhomogeneous one-dimensional arrays of tunnel junctions

A general expression is given for the change in free energy when a charge tunnels through a junction in a one-dimensional array of N metallic islands with arbitrary capacitances and arbitrary background charges. This is used to obtain expressions for the (average) threshold voltage of the Coulomb blockade for a few characteristic geometries. We find that including random background charges has a large effect on the N-dependence of the threshold voltage: In an array with identical junction capacitances C and gate capacitances C_g, the threshold voltage, averaged over the background charge, is proportional to N^a, where {a} crosses over from 1/2 to 1 when N becomes larger than 2.5\sqrt{C/C_g}.

cond-mat.mes-hall↗

arXiv1994

On Thermometer Operation of Ultrasmall Tunnel Junctions

The temperature dependence of the I-V characteristics of many single-electron tunneling devices enable thermometer operation of these systems. We investigate two normal conducting kinds of them, {\sl (a)} a single junction in a high-impedance environment, and {\sl (b)} a double junction. The characteristics of both devices show a crossover from Coulomb blockade at low temperatures to ohmic behavior at high temperatures. The related differential conductivity dip allows the determination of the junctions temperature. Both configurations {\sl (a)} and {\sl (b)} are expected to work at least within the range $0.5\leβE_{\rm C}\le 10$, where $E_{\rm C}$ is the Coulomb energy of the system under investigation. We present an analytical solution for both low- and high-temperature case of {\sl (a)} and {\sl (b)} as well as numerical results and their fit, including the effect of co-tunneling in case of a double junction.

cond-mat↗