Flexible self-powered DUV photodetectors with high responsivity utilizing Ga2O3/NiO heterostructure on buffered Hastelloy substrates

In this research, beta-Ga2O3/NiO heterostructures were grown directly on CeO2 buffered Hastelloy flexible substrates. With pulsed laser deposition under high temperatures, as-grown beta-Ga2O3 and NiO thin films have a preferred out-of-plane orientation along the -201 and (111) directions. This is due to the ideal epitaxial ability of the CeO2 buffer layer, which serves as a perfect template for the epitaxial growth of single-oriented NiO and beta-Ga2O3 by creating a constant gradient from CeO2 (2.7 angstrom along (001)) to NiO (2.9 angstrom along (110)), and eventually to beta-Ga2O3 (3.04 angstrom along (010)). The Hastelloy substrates endow photodetectors with good deformability and mechanical robustness. Moreover, owing to the type-II band alignment of beta-Ga2O3/NiO heterostructures, the photodetectors have a good photocurrent at zero bias under 284 nm of light illumination. In addition, the photocurrent is significantly higher than when using an analogous heterostructure (as described in some previous reports), because the beta-Ga2O3 and NiO thin films are crystalized along a single orientation with fewer defects.