Solution processed, vertically aligned, AZO nanocolumn array for chemiresistive sensor application with UV-enhanced sensitivity

Abstract

In this work, a wide and highly sensitive chemiresistive sensor has been developed based on the AZO nanocolumn array film. This is meant for the room detection of H2O2 under UV illumination. A cost-effective one step multi-layers growth process was adopted for the synthesis of the AZO nanocolumn array. The experimental studies were done by scanning electron microscopy (SEM), transmission and electron microscopy (TEM).Then X-ray diffraction confirmed that the AZO column array was closely packed, connected, vertically aligned, and polycrystalline, with a high surface area. This structure ensures better electrical conduction over random and separated nanostructures. The hall-effect measurement indicates that the AZO film was n-type, with high conductivity (3.60 × 103 Ωcm), high carrier density (11.3 × 1020cm−3) and with acceptable mobility (0.95 cm2/Vs). The x-ray photoemission spectroscopy suggests that the AZO film consists of a large amount of adsorbed oxygen-related species at the sheath layer of the thin-film, which is vital for sensors. By the UV light activation, sensors based on the AZO nanocolumn array exhibited enhanced H2O2 detection properties at room temperature. At a concentration from 15 μM to 30 mM, H2O2 sensitivity evaluated by relative response was remarkably increased from 15% to 36%. The operation under ambient conditions and wide range sensing shows that this chemiresistive AZO sensor is adequate for biomedical and environmental applications.