Influence of Temperature on the Reliability of Graphene-Based Ozone Sensors

Graphene-based sensors are promising candidates for highly sensitive detection of chemical species from the environment. The main challenges to their application lie in their unspecific sensitivity and their lack of stability and reliability. Here, we report our assessment of chemiresistive graphene gas sensors under extended temperature, humidity, and ozone stress. We fabricated our sensors with inkjet-printed graphene flakes. These were electrically characterized by monitoring their change in resistance with respect to temperature and time in a 40% humidity and ozone-rich environment. Higher stress temperatures resulted in a faster increase in resistance in the sensors. This Arrhenius behavior suggests degradation by a temperature-activated mechanism, with an activation energy of 0.63 eV, consistent with literature data of ozone physisorption/chemisorption pathways. This degradation mechanism and mode were confirmed using surface-sensitive techniques, in particular X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. The results reveal the chemical composition and defect density of graphene after stress. Its decomposition rate was higher on the SiN substrate than on the gold electrode. The results serve to understand the underlying mechanisms of failure and support the development of a model for sensor reliability and failure prediction in the context of varying temperatures.