A novel high performance photodetection based on axial NiO/β-Ga₂O₃p-n junction heterostructure nanowires array

Axial NiO/β-Ga₂O₃heterostructure (HS) nanowires (NWs) array was fabricated on Si substrate by catalytic free and controlled growth process called glancing angle deposition technique. The field emission scanning electron microscope image shows the formation of well aligned and vertical NWs. A typical high resolution transmission electron microscope image confirms the formation of axial HS NWs consisting ofβ-Ga₂O₃NW at the top and NiO NW at the bottom with an overall length ∼213 nm. A large photo absorption and also photoemission was observed for axial NiO/β-Ga₂O₃HS NW as compared to the NiO/β-Ga₂O₃HS thin film sample. Moreover, x-ray photoelectron spectroscopy analysis prove that there are higher oxygen vacancies with no deviation in electronic state after the formation of axial HS NW. Also, a high performance photodetector (PD) with a very low dark current of 6.31 nA and fast photoresponse with rise time and fall time of 0.28 s and 0.17 s respectively at +4 V was achieved using the axial NiO/β-Ga₂O₃HS NWs. The type-II HS p-n junction formation and efficient charge separation at the small wire axis also makes this design to operate in self-powered mode.