Pyroelectric effect in Y–Ba–Cu–O thin films under laser illumination

The thermoelectric response of amorphous, semiconducting Y–Ba–Cu–O thin films was investigated by illumination with 150 ps optical pulses at 1064 nm and with a continuous wave at 493 nm ~argon laser!. The measured unbiased voltage response was consistent with pyroelectricity. At high pulse energies, the voltage response saturated due to the saturation of the spontaneous polarization. The pulsed responsivity was limited by the short pulse duration compared to the thermal time constant of the structure. The electrical time constant for the change in the spontaneous polarization was estimated to be 50 ns. © 1999 American Institute of Physics. @S0021-8979~99!02802-9#