HTSC polaronic quasiparticle injection devices with an organic copper (II) phthalocyanine injector

We report the nonequilibrium effect of polaronic quasiparticle (QP) injection using an organic injector in a high T_c three terminal device. The organic, copper (II) phthalocyanine (Cu-Pc), used as the injector, is a photoconductor and a p-type semiconductor. The transport properties of Au/Cu-Pc/Bi₂Sr₂CaCu₂O_8+δ (BSCCO) tunnel junctions were investigated in the dark and under the He-Ne laser (λ=632.8 nm) radiation. We observed that the injection of polaronic QP from the organic Cu-Pc film into the BSCCO film generated a substantially larger nonequilibrium effect as compared to the normal QP injection current. We could increase the current gain by He-Ne laser excitation of the organic photoconductor injector. The tunneling spectroscopy of a Cu-Pc/BSCCO junction exhibited an enhancement of the zero bias conductance peak under the He-Ne laser excitation. The above phenomena are of importance in developing optically controlled three terminal superconducting devices.