High self-powered UV-Visible photoresponse in ZnO/CuO heterostructure photodetectors, the influence of ZnO window layer thickness

In this study, we have fabricated ZnO/CuO heterostructure photodiodes on FTO substrate using the RF-sputtering method and investigated the influence of the ZnO thickness (390 and 470 nm) on their photoresponse in the wide range of UV to red wavelengths. The layers were characterized by FESEM, XRD, Raman, PL, and UV-Vis. Spectra, also I-V, I-V-T (295-340 K), and I-t in the dark and under illumination. We found: (1) the constituent layers have a polycrystalline nature, monoclinic phases for CuO and wurtzite phase for ZnO layers; (2) in addition to rectifying behavior, the I-V-T analysis confirmed that the current mechanism of these junctions follows the recombination model; (3) both samples have the potential of photovoltaic properties with self-powered ability; (4) sample with thinner ZnO layer has the highest photoresponse ratio (ILight/IDark) of 5.5 x 104-2.6 x 103 through UV to red light illumination and fast response time of 45-50 ms.

Automated summary

We fabricated ZnO/CuO heterostructure photodiodes on FTO substrate using the RF-sputtering method and studied the effect of ZnO thickness on their photoresponse. Various characterizations were performed, and it was found that both samples showed potential for photovoltaic properties, with the sample with a thinner ZnO layer exhibiting the highest photoresponse ratio and fast response time.