Performance analysis of flexible Pd/ZnO/ITO ultraviolet photodetectors

Fabrication of nanostructure thin-film semiconductors onto flexible substrates is a critical issue for developing wearable devices for biometric or environmental parameter measurement. With this study, the ZnO thin film ultraviolet photodetectors on a flexible PET substrate are successfully fabricated at ambient temperature. The Pd/ZnO/ITO ultraviolet photodetection performance was investigated. Nanostructure ZnO thin film was grown on a flexible ITO coated PET substrate using hydrothermal method and Pd electrode metallization is carried out by thermal evaporation technique. A device’s I-V characteristics were determined in dark and illuminated settings throughout a range of voltage from -5 V to 5 V. Electrical performance parameters were extracted using the standard thermionic emission theory and Cheung’s approach. The thermionic emission test results in a barrier height of 0.729 eV and an ideality factor of 2.31, while the Cheung technique results in a barrier height of 0.722 eV, and an ideality factor of 1.8, and series resistance of 5.48 kΩ. The present study shows that Cheung’s methodology is a more accurate method for predicting the Pd/ZnO/ITO Schottky diode parameters, since it is taking into account the presence of series resistance. By UV illumination, we explored the proposed device photodetection characteristics, such as responsivity, and quantum efficiency that found to be, 0.255 A/W, and 0.85 respectively. On a flexible substrate, it was feasible to construct a photodetector Schottky diode ZnO film via hydrothermal growth.