Josephson junction oscillators as probes of electronic nanostructures

We have fabricated high-quality planar Nb/AlOx/Nb Josephson junctions on-chip adjacent to quantum dots in a near surface two-dimensional electron gas in a GaAs/AlGaAs heterostructure. When used as a voltage-tunable oscillator coupled capacitively to a quantum dot, the Josephson junction can produce a localized time-dependent potential of 200 mu V across the dot at frequencies in excess of 300 GHz. The fabrication process involves five separate patterning and processing steps to define the multilayer integrated device. (C) 1998 American Institute of Physics. [S0021-8979(98)01822-2].