Influence of annealing temperature on morphological, optical and UV detection properties of ZnO nanowires grown by chemical bath deposition

• Low-cost chemical bath deposition method was used to fabricate the ZnO nanowires.
• Influences of heat treatment on the structural and optical properties of the ZnO NWs were investigated.
• The origin of defects responsible for photoluminescence emissions in ZnO nanowires was investigated.
• ZnO nanowire arrays were applied as metal-semiconductor-metal ultraviolet photodetectors.
• Heat treatment improved the photodetection properties strongly.

Chemical solution deposition is a low-temperature method with possibly the lowest-cost for growing zinc oxide (ZnO) nanowires (NWs) on an amorphous glass substrate. A ZnO seed layer is needed to initialize the uniform growth of oriented nanowires. In the present work, we deposited the seed layer onto the glass substrate using radio frequency magnetron sputtering system. The ZnO NWs were fabricated on the seeded substrate by immersing them in a chemical bath containing zinc nitrate and hexamethylenetetramine (HTMA) aqueous solution. Several properties of as-grown ZnO NWs and annealed ZnO NWs at different temperatures in pure oxygen atmosphere were investigated. Well-defined ZnO nanowires almost perpendicular to substrate surface were observed through field emission scanning electron microscopy micrographs. X-ray diffraction measurements showed that all ZnO samples possessed a typical wurtzite structure with high crystallinity and no other impurity phases. The results of UV–Visible spectroscopy and room temperature photoluminescence implied that increasing the annealing temperature could have a significant influence on the performance of samples. The ZnO-based interdigitated metal–semiconductor–metal (MSM) was produced using the thermal evaporation of silver contacts. The results of current–voltage and transient response measurements demonstrate that despite using the low-cost thin film techniques, high responsivity was obtained.

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