Investigating the photodetection performance of self-biased Au/PZT/ FTO and Au/PZT/Au/FTO UV photodetectors

Ferroelectric materials are attracting increasing attention for self-biased ultraviolet (UV) photodetection applications owing to their photovoltaic characteristics induced by ferroelectric polarization. However, the low depolarization and limited separation of photogenerated carriers hinder their application potential for UV light detection. Here, good quality polycrystalline ferroelectric PbZr0.3Ti0.7O3(PZT) thin films were fabricated on Au/ FTO and FTO substrates via a facile sol-gel technique for investigating photovoltaic characteristics. The P-E loop observed for the PZT film grown on FTO demonstrates excellent ferroelectric properties, which are further enhanced by introducing (111)-oriented Au interlayer. The I-V curve measurements of the Au/PZT/Au/FTO structure device demonstrated a large photovoltaic response with a Voc = 0.98 V and Isc = 59.45 nA under 340 nm light illumination compared to that of Au/PZT/FTO device (VOC = 0.32 V and Isc = 28.19 nA). The study revealed that the photodetector parameters, responsivity (0.135 A/W), detectivity (7.10 +/- 0.03x1011), and response time (tau r/tau d = 46 ms/81 ms) of FTO/Au/PZT-based UV photodetector are superior to that of FTO/PZT device due to its improved ferroelectricity. Moreover, the direction of the photocurrent can be switched by altering the poling states of the PZT ferroelectric.