Electron tunneling through large area vacuum gap-preliminary results

We have obtained tunneling currents of over 10 /spl Aring/ through the vacuum gap between conformal electrodes having an effective area on the order of 0.1-1 cm/sup 2/. The large area vacuum gap is obtained by using a surface replication method that allows for two electrodes to have precisely matched topographies. The width of the vacuum gap within the range of 30-100 /spl Aring/ is regulated using piezoelectric actuators. These same actuators are used to regulate angles between the electrodes. Measured I-V characteristics show that the overall current through the system can be represented as the sum of the tunneling current and the current running through the short circuits between electrodes, and that tunneling current becomes dominant at distances greater than 30 /spl Aring/. The dependence of the capacitance and conductance on the distance between electrodes is in good agreement with the simple model of electrodes separated by a vacuum gap. Such an electron tunneling device could be used for cooling and power generation, as well as for other applications.