Low-voltage-worked photodetector based on Cu2O/GaOOH shell-core heterojunction nanorod arrays

Cu2O/GaOOH shell-core heterojunction nanorod arrays (NRAs) were constructed by coating Cu2O on GaOOH NRAs through a simple and economical chemical bath deposition route. The obtained GaOOH NRAs crystalized in orthorhombic structure, with diameter range of 80-200 nm and an average height of 1 μm. A p-n junction constructed with a p-type narrow bandgap Cu2O and a n-type wide bandgap GaOOH NRAs shows a broad photoresponse region ranging from 239 nm to 570 nm. The photodetector (PD) based on Cu2O/GaOOH heterojunction exhibited a photoresponsivity (Rλ) of 6.95 A/W and an external quantum efficiency (EQE) of 2361% under the illumination of 365 nm ultraviolet (UV) light with a light intensity of 1.4 mW/cm2 at a bias voltage of 0.5 V. What more interesting is that the PD still shown an obvious photoelectric response to 532 nm light with a very low bias voltage of 0.5 mV. Such low-voltage-worked feature of Cu2O/GaOOH PD can be attributed to the built-in electric field formed at the interface between Cu2O and GaOOH, indicating a potential application in low power devices.