Photoresponse of Zener tunneling junctions of Pb(Ti,Zr)O3/SrTiO3 at low temperature

Temperature (T) dependent current–voltage (IV) characteristics of epitaxial Pb(Ti,Zr)O3/SrTiO3 heterojunctions exhibiting the characteristics of Zener tunneling are measured in the dark and in the light. Ultraviolet light is found to induce a prominent photovoltaic effect at all T down to at least 50 K, while the open circuit voltage increases with decreasing T. In the dark the reverse bias current increases with decreasing T. In the light the reverse bias current at low T is a superposition of a photovoltaic current and a small component that is identical to the reverse bias current in the dark. These observations indicate that the anomalous T dependence of the reverse bias current in the dark is attributable to the tunneling from the Pb(Ti,Zr)O3 band to the SrTiO3 band. Additionally, short pulse voltages modulate the tunneling current, which is retained.