Effect of Ultraviolet Light on Mn3O4 Thin Films that are Grown Using SILAR for Room-Temperature Ozone Gas Sensors

Successive ionic layer adsorption and reaction (SILAR) is a promising technique to fabricate gas sensors at room temperature. However, the quality of the films is poor, leading to reduced surface area and increased defects within the film structure, thus decreasing the overall gas response. Inferior film quality also negatively affects the stability and reproducibility of the gas sensors over time. This study determines the effect of UV treatment on the structural, morphological, and ozone (O 3 ) gas-sensing properties of p-type Mn 3 O 4 thin films. As UV treatment time increases, the O 3 gas-sensing characteristics increase because a porous structure with a higher surface area is formed and electrical conductivity is increased. Under a UV intensity of 20 mW cm −2 , the Mn 3 O 4 sensor exhibits gas response, response time, and recovery time of 1.62, 58, and 39 s, respectively, against 5 ppm concentration of O 3 gas. Moreover, the Mn 3 O 4 gas sensor exhibits excellent long-term stability showing around 3% variation in gas response over 60 d. This strategy allows the deposition of high-quality p-type Mn 3 O 4 thin films using SILAR for applications in flexible gas sensors.