Single-electron charging effects in one-dimensional arrays of ultrasmall tunnel junctions

Abstract

Coulomb blockade of single-electron tunneling and high sensitivity to an external electric field has been observed for 1D series arrays of ultra-small-area (<0.1\ifmmode\times\else\texttimes\fi{}0.1 \ensuremath{\mu}${\mathrm{m}}^{2}$) tunnel junctions, made of Al/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{O}}_{\mathrm{y}}$/Al, at helium temperatures. In particular, the dc voltage V across the array responds strongly to a voltage ${U}_{g}$ applied to a control electrode. For an array of thirteen junctions, the voltage gain ${K}_{V}$=\ensuremath{\Vert}\ensuremath{\delta}V/\ensuremath{\delta}${U}_{g}$\ensuremath{\Vert} of the resulting sub-single-electron- transistors reached 0.2, while the charge sensitivity of the device was as high as 2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$e/${\mathrm{Hz}}^{1/2}$ at a frequency f=10 Hz.