Bias voltage dependence of a flux-sensitive Al/GaAs/Al (SNS) interferometer

We report new results on interferometers based on high transparency superco nductor-semiconductor-superconductor junctions composed of Al and highly do ped GaAs. The fabricated devices consist of planar de-SQUID like geometries with an effective flux-sensitive area of about 100-150 mu m(2). At zero bi as voltage the fabricated interferometers typically exhibit 3% sinusoidal m odulation of the conductance as a function of a magnetic field applied perp endicular to the loop. The conductance modulation is caused by resonant And reev states in the normal GaAs region of the device. With increasing bias v oltage of the order of a few microvolts the device is driven out of resonan ce and the conductance oscillations are extinguished. However, at higher bi as voltage corresponding to the superconducting energy gap of Al (178 mu V) the conductance oscillations reappear but with reduced amplitude.