Double‐Phase Ga‐Doped In 2 O 3 Nanospheres and Their Self‐Assembled Monolayer Film for Ultrasensitive HCHO MEMS Gas Sensors

sensors also show high consistency (fluctuations of only 8.3%). Besides, a handheld device is developed to enable real-time monitoring and early warning of indoor HCHO at ppb-level. Based on experimental results and DFT theoretical calculation, the enhanced sensing mechanism is revealed, which is correlated with the optimization of electronic band structure by Ga doping and the appearance of double-phase heterostructures caused by Ga doping. Therefore, the relationship between electronic structure and gas sensing properties has also been established. This work significantly introduces a novel approach for the mass production of MEMS gas sensors, ensuring high sensitivity, repeatability and consistency.