Design optimization of FET-type gas sensor considering device characteristics, sensitivity, power, noise, and SNR

The design of the FET-type gas sensor affects various sensor performance factors such as sensitivity, noise, and power consumption. However, few studies comprehensively consider the impact of sensor design on the factors. Here, we show how the design of FET-type gas sensors influences a variety of performance factors and provide design guidelines for FET-type gas sensors. Sensors with several sensing material areas and FET channel areas are fabricated, and fabricated sensors are modeled using Technology Computer-Aided Design (TCAD) simulation to obtain the coupling ratio between the sensing material and FET channel and to investigate the gas response mechanism of the FET-type sensor. As the area of the sensing material increases, the sensitivity of the sensor increases due to the increase in the coupling ratio. Meanwhile, the area to be heated by the micro-heater also increases, thereby increasing power consumption. As the FET channel area decreases, the coupling ratio increases, resulting in better sensitivity, but the noise of the sensor increases. Therefore, it is desirable to design the FET-type gas sensor using sensitivity/power and signal-to-noise ratio (SNR) as indicators in consideration of sensitivity, power consumption, and noise. A FET-type gas sensor can be optimized by considering the performance factors of trade-offs, setting an optimization indicator suitable for the application, and then selecting design parameters that maximize the indicator. As a proof of concept, we show processes to optimize the horizontal floating-gate FET (HFGFET)-type gas sensor using ΔID/power, SNR, SNR/power, and (SNR/power)/size as optimization indicators.