Ultraviolet Photodetection Based on High-Performance Co-Plus-Ni Doped ZnO Nanorods Grown by Hydrothermal Method on Transparent Plastic Substrate

Abstract

A growth scheme at a low processing temperature for high crystalline-quality of ZnO nanostructures can be a prime stepping stone for the future of various optoelectronic devices manufactured on transparent plastic substrates. In this study, ZnO nanorods (NRs) grown by the hydrothermal method at 150 °C through doping of transition metals (TMs), such as Co, Ni, or Co-plus-Ni, on polyethylene terephthalate substrates were investigated by various surface analysis methods. The TM dopants in ZnO NRs suppressed the density of various native defect-states as revealed by our photoluminescence and X-ray photoelectron spectroscopy analysis. Further investigation also showed the doping into ZnO NRs brought about a clear improvement in carrier mobility from 0.81 to 3.95 cm2/V-s as well as significant recovery in stoichiometric contents of oxygen. Ultra-violet photodetectors fabricated with Co-plus-Ni codoped NRs grown on an interdigitated electrode structure exhibited a high spectral response of ~137 A/W, on/off current ratio of ~135, and an improvement in transient response speed with rise-up and fall-down times of ~2.2 and ~3.1 s, respectively.

Morphology Related Defectiveness in ZnO Luminescence: From Bulk to Nano-Size

“…The investigation of ZnO crystals and thin films has attracted great interest in the field of solid-state optoelectronics [ 1 ]. Its optical properties, electrical conductivity and radiation hardness make ZnO a good candidate for transparent thin-film transistors, laser diodes, light emitting diodes and photodetectors [ 2 , 4 , 5 ]. In particular, ZnO is promising for photonic applications in the UV and blue spectral range [ 3 , 6 ] based on exciton emission even at room temperature (RT) because of its wide band gap (~3.4 eV [ 1 ]) and large excitonic binding energy (~60 meV [ 7 ]), that is about 2.4 times higher than thermal energy (k B T) at 298 K. Ferromagnetism at RT has been observed in ZnO doped with transition metals leading to potential application in spintronics devices [ 3 ].…”

High-Entropy Oxides: Advanced Research on Electrical Properties

“…By investigating the relationship between diffusion coefficient and oxygen partial pressure during the preparation of (Co,Cr,Fe,Mn,Ni) 3 O 4-y , Grzesik et al [55] concluded that oxygen content of the final product would be reduced at low oxygen partial pressure levels, implying that corresponding oxygen vacancy concentration would be higher than at high oxygen partial pressure. So, by means of controlling oxygen vacancies, we could regulate the devices' electrical performance [56].…”

Effects of Seed-Layer N2O Plasma Treatment on ZnO Nanorod Based Ultraviolet Photodetectors: Experimental Investigation with Two Different Device Structures

“…A highest spectral responsivity R of ~1.5 × 10 5 A/W was obtained from the PDs at a wavelength of 360 nm, as revealed in Figure 7, when plasma-treated for 6 min due to improvement in ZnO material quality. The UV sensing mechanism of the IDE pattern-based PDs is based on the modulated photoconduction through the crosslinked NR-NR bridges caused by O2 adsorption and desorption on the NR surface [28]. In the dark state, expanded ZnO surface depletion caused by O2 -adsorption brings about a minimum cross-section of conducting area and leads to a small dark current flowing inside the NR.…”

“…Figure 8. I-V characteristics of (a) the HEMT-based and (b) IDE pattern-based UV PDs.The UV sensing mechanism of the IDE pattern-based PDs is based on the modulated photoconduction through the crosslinked NR-NR bridges caused by O 2 adsorption and desorption on the NR surface[28]. In the dark state, expanded ZnO surface depletion caused by O 2 adsorption brings about a minimum cross-section of conducting area and leads to a small dark current flowing inside the NR.…”