UV-enhanced O2 sensing using β-Ga 2 O 3 nanowires at room temperature

Oxygen sensors based on (3-Ga2O3 nanowires were prepared by a chemical vapor deposition method and investigated in detail. (3-Ga2O3 nanowires grew on sapphire substrate at 1100 degrees C with Au as a catalyst. The polycrystalline structure was confirmed according to the X-ray diffraction (XRD) patterns. Scanning electron microscope (SEM) images revealed the average diameter of the nanowires was 150 nm. The ratio of Ga to O was 0.765 according to energy dispersive spectroscopy (EDS) results. Photoluminescence emissions at 445 and 484 nm originated from oxygen vacancies and gallium-oxygen vacancy pairs. Both EDS results and photoluminescence revealed intrinsic oxygen vacancies in (3-Ga2O3 nanowires. We coated the (3-Ga2O3 nanowires on an interdigitated electrode to fabricated an oxygen sensor. Under ultraviolet light irradiation, at room temperature, the sensor's response rise time and recovery time were 1034 s and 1283 s to 600 ppm oxygen, those were 1290 s and 1709 s to 1200 ppm oxygen. The mechanism of oxygen sensing was discussed.