Fabrication of UV photodetector using needle-shaped ZnO nanostructure arrays prepared on porous silicon substrate by a facile low-temperature method

Abstract

Arrays of vertically well-aligned ZnO nanoneedles were successfully grown on seeded porous silicon substrate through electric field-assisted aqueous solution method. The surface morphologies of needle-like ZnO nanostructures were studied using field-emission scanning electron microscopy and transmission electron microscopy. Meanwhile, structural and morphological analyses displayed wurtzite nanostructures with strong c-axis oriented crystal structure and preferred (0 0 2) orientation. The photoluminescence spectra revealed intensive and sharp ultraviolet light emission at 382 nm with high intensity and low broad visible light emission in a 500–700 nm wavelength range confirming high optical quality of the formed ZnO nanoneedles. The fabrication and characterization of a metal–semiconductor–metal ultraviolet photodetector based on ZnO nanoneedles were studied. Upon exposure to 325 nm light (1.6 mW/cm2) at 3 V bias voltage, the device displayed 1.98 A/W responsivity and 10.48 photosensitivity. Furthermore, the response and the recovery times measured under these conditions were 86 and 83 ms, respectively.