Heterojunction Photodiodes Based on Honeycomb Structures for Ultraviolet Detection

Abstract

The p-NiO/n-ZnO heterojunction device based on honeycomb structures was fabricated by RF sputtering method. The structural and optical properties of the p-NiO/n-ZnO heterojunction were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, field-emission scanning electron microscope (FE-SEM), and current–voltage (I–V) photocurrent measurements. The XRD spectra indicate that ZnO films were of hexagonal wurtzite structures, preferentially (002) oriented. SEM show that the spherical polystyrene stacking on hexagonal close-packing lattice structure. Optical measurements showed that the honeycomb structures exhibited the maximum haze values up to 50% at wavelength range 380–800 nm. The I–V curve of the heterojunction demonstrates obvious rectifying diode behavior in a dark environment. The lowest of leakage current is 8.23×10-9 A/cm2 for p-NiO/n-ZnO heterojunction device.

Self-powered spectrum-selective photodetectors fabricated from n-ZnO/p-NiO core–shell nanowire arrays

“…To our knowledge, this value is the highest currently reported result for p-NiO/n-ZnO heterojunction based PDs. 27,33,34 Meanwhile, it is over twice that of a p-GaN/n-ZnO nanoparticle wavelength-selective photodiode (0.225 mA W À1 ), 35 and at least two orders of magnitude larger than that of an epitaxially grown p-GaN/n-ZnO heterojunction for selective UV detection (about 1.0 Â 10 À3 mA W À1 ). 36 Another advantage of the p-n type PDs is the fast response speed compared with the photoconductive PDs, of which the decay time is usually in the order of several seconds due to the presence of deep level traps and the adsorption of gas molecules (e.g.…”