COOPER PAIRS AND QUASI-PARTICLES TUNNELING IN LIGHT-SENSITIVE JUNCTIONS.

Tunneling experiments have been performed on lead-cadmium sulfide-lead light-sensitive junctions. In the framework of an equivalent rectangular average barrier model and assuming an effective mass approximation, experimental current-voltage and conductance voltage characteristics have been employed to evaluate the tunneling barrier parameters in dark conditions and at increasing light exposure levels. A parabolic shape for the barrier has been assumed to give a qualitative account for the behavior of the junctions with the light exposure time. Measurements of the temperature dependence of the light-induced dc Josephson current also supports the deviation from the 'rectangular' shape of the tunneling barrier at heavy illumination levels.