Enhancement of pyroelectric signal by continuous ultraviolet illumination of epitaxial Pb(Zr_0.2Ti_0.8)O₃ films

The pyroelectric signal generated by an epitaxial Pb(Zr_0.2Ti_0.8)O₃ film can be enhanced by continuous illumination with ultraviolet (UV) light. The measured signal increases more than 2 times at low modulation frequencies of the incident infrared (IR) radiation (∼10 Hz) and at wavelengths where the short-circuit photocurrent presents the maximum value (∼280–300 nm). The tentative explanation is that the changes in polarization induced by the temperature variation under modulated IR illumination are generating a variable internal electric field, able to collect the photogenerated carriers produced under continuous UV illumination leading to an additional signal in phase with the pyroelectric one. This finding could be exploited for designing pyroelectric detectors with enhanced characteristics by combining both UV and IR responses.