Photodiode properties of epitaxial Pb(Ti, Zr)O3/SrTiO3 ferroelectric heterostructures

A substantial photovoltaic effect is found in heterostructures of typical ferroelectric oxides. Pb(Ti, Zr)O-3/Nb-doped SrTiO3, especially, exhibits current-voltage characteristics of the photovoltaic effect of a typical pn junction (p: hole carrier type, n: electron carrier type). A preliminary nonoptimized device shows high performance such as open circuit voltage of 0.7-0.8 V, external conversion efficiency of 0.6%-0.8%, and response time faster than 20 mus for ultraviolet light at room temperature, suggesting the potential of this diode as a new class of photodiode. The results support the formation of a pn like junction by ferroelectric oxides. Additionally, the photovoltaic characteristics are tuned by the application of short pulse voltages and retained. (C) 2001 American Institute of Physics.