NO₂ gas response improvement method by adopting oxygen vacancy controlled In₂O₃ double sensing layers

Recent studies have shown that the sensing capabilities of NO₂ gas sensors can be enhanced by controlling the amount of oxygen vacancy (V_O) in the sensing layer. The sensing layer of the resistor-type sensor can be divided into two regions close to the surface and substrate interface. To control the amount of oxygen vacancy in the sensing layer, oxygen gas flow rate during sputtering is regulated. We fabricate the In₂O₃ gas sensor by vertically adjusting the oxygen vacancy. We place an oxygen vacancy-poor layer on the lower sensing layer and an oxygen vacancy-rich layer on the upper sensing layer. The resistance characteristics of the fabricated sensor are measured through the transmission line method. The NO₂ gas sensing performance of the double sensing layer sensor and the single sensing layer sensor is measured. The best response and fastest response time are observed in the sensor with oxygen vacancy controlled double sensing layer.