Sub-bandgap photocurrent effects on dynamic pyroelectric measurement in Pt/PbTiO3/Nb:SrTiO3 heterostructures

We have studied how sub-bandgap photocurrents affect dynamic pyroelectric measurements in ferroelectric Pt/PbTiO3/Nb:SrTiO3 heterostructures. Currents generated in the PbTiO3 capacitors under pulsed laser illumination were found to be a combination of pyroelectric and photoelectric signals. We show that time-domain measurements can be used to separate the two contributions and obtain accurate pyroelectric hysteresis loops. Photocurrents, also present for excitation laser photon energies below the bandgap of the PbTiO3 ferroelectric, were assigned to charge carriers generated at the electrode interfaces. Hysteresis loops were observed for both current components, indicating that photocarrier extraction from the ferroelectric heterostructure can be controlled by choosing a suitable domain polarity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736262]