Infrared Photocurrent Study of PZT/YBCO and PMSZT/YBCO Heterostructures

摘要

Ferroelectric Pb(Zr052Tio,H{)03 (PZT) (001) and (Mn,Sn) doped-PZT (PMSZT) (001) thin films have been integrated to high Tc superconducting c-oriented YBa2Cu30?-x (YBCO) films for use as infrared detectors. The films were grown on LaAlO3(100) substrates by the pulsed laser deposition technique. The photocurrent responses of the PZT/YBCO and PMSZT/YBCO heterostructures fabricated as infrared (IR) detector have been measured from room temperature up to the ferroelectric phase transition temperatures. A stable photocurrent was observed to increase with increasing temperature throughout the temperature range. It was observed that the photocurrent of PMSZT/YBCO IR detector was significantly higher than that of the PZT/YBCO IR detectors in the temperature range of 20-170°C. The current enhancement with temperature was found to be strongly polarization dependent and is due to the change of the pyroelectric coefficient of the PZT and PMSZT thin films with temperature. The YBCO thin films in the heterosiructure were not used for their superconducting properties, but for their IR reflector-conductive electrode properties and as an atomic template for PZT/PMSZT epitaxial growth. With the high dielectric constants of PZT (600-800) and PMSZT (300-450) measured in this work, and the stable photocurrent in the infrared region (above 1 nm), the PZT/YBCO and PMSZT/YBCO heterostructures are believed to be suitable materials for use in infrared detectors applicable at temperatures higher than room temperature