Proposition of optimal self-curing method in horizontal-floating gate FET-type gas sensors for reliability improvement

Gas sensing technology has seen rapid advancements in recent years, finding applications in air quality monitoring, food freshness inspection, and medical diagnosis. However, to successfully integrate gas sensors into these applications, it is crucial to ensure their stability and long-term reliability. While previous studies have primarily focused on improving response, sensitivity, and selectivity, there has been limited research on enhancing their reliability. This study aims to address this gap by proposing a method to improve the reliability of horizontal floating-gate FET-type gas sensors using a self-curing approach. When the sensor is exposed to the repetitive program/erase operation, the FET transducer used as a sensor platform is damaged by the Fowler-Nordheim tunneling-induced stress. A significant increase in the trap density inside the gate oxide is observed after the P/E cycling. The parasitic bipolar junction (PBJT) inherent to the FET transducer flows a large current via the entire channel, generating a Joule heat. The trap is decreased by the annealing effects of the Joule heat, and the damaged gate oxide is fully recovered by the curing. The proposed PBJT curing can effectively improve the reliability of the sensor using the internal operation of the FET transducer without using bulky external equipment.