Photochemically-Activated p-Type CuGaO₂ Thin Films for Highly-Stable Room-Temperature Gas Sensors

The photochemical activation process is a promising way to operate metal oxide gas sensors at room temperature. However, this technique is only used in n-type semiconductors. In this study, we report a highly stable p-type copper gallium oxide (CuGaO₂) gas sensor fabricated through the facile sol-gel process. The sensor is capable of detecting O₃ gas at room temperature, and its gas response can be further enhanced by ultraviolet (UV) activation. The highest gas response of 7.12 to 5 ppm O₃ gas at a UV intensity of 10 mW cm⁻² is achieved at room-temperature. In addition, the CuGaO₂ sensor shows excellent long-term stability, with a degradation of approximately 3% over 90 days. These results strongly support the solution-processed CuGaO₂ as a good candidate for room-temperature gas sensors.