Batch fabrication of formaldehyde sensors based on LaFeO3 thin film with ppb-level detection limit

Abstract

High-performance formaldehyde sensors act a significant role in environmental monitoring and industrial gas analysis. However, the traditional side-heating type gas sensors fabricated by handicraft-like brush-painting or drop-casting methods still suffer from poor detection limits and the difficulty of massive fabrication, which hinders the further practical applications of gas-sensing devices. Herein, the uniform LaFeO3 thin film prepared through a facile sol-gel method combining with spin coating is proposed to achieve batch-fabricated gas sensors for the detection of gaseous formaldehyde. The fabricated gas sensor exhibits a low detection limit as low as 50 ppb toward gaseous formaldehyde, which is lower than the guideline value (80 ppb) limited by World Health Organization. Furthermore, the gas-sensing properties of batch-fabricated thin film gas sensors reveal satisfactory uniformity and replicability with low device-to-device deviation. The maximum variation of baseline resistance between different batch samples is only 5.4%, and the maximum drift of the response value toward formaldehyde is only 6.5%. The favorable gas-sensing performances and high replicability for the sensors might be attributed to the controllable fabrication process that can be completely compatible with the well-established semiconductor technics. This work will open up an effective pathway to prompt high-performance formaldehyde sensors with ppb-level detection limits toward practical applications.