Improved signal-to-noise-ratio of FET-type gas sensors using body bias control and embedded micro-heater.

• Effects of body-to-source junction bias on SNR in the FET-type gas sensor with a localized micro-heater are investigated. • Sensing material, a 12 nm-thick n -type semiconducting In 2 O 3 , is prepared through radio frequency magnetron sputtering. • When a forward body-to-source junction bias of 0.5 V is applied to the sensor, the 1/ f noise decreases by the factor of ∼10. • Limit of detection of the gas sensor for NO 2 gas can be improved from 0.55 ppb to 0.27 ppb by using a forward body-to-source junction bias of 0.5 V. This paper investigates the effects of body-to-source junction bias (V BS) on signal-to-noise-ratio (SNR) of Si metal-oxide-silicon field effect transistor (FET)-type gas sensor with a localized embedded micro-heater. Sensing material, 12 nm-thick n -type semiconducting In 2 O 3 , is prepared through radio frequency magnetron sputtering. NO 2 is used as a test gas to investigate the gas sensing characteristics of the sensor. By using the embedded micro-heater, the temperature of the sensing area can be raised to an extent required for the gas reaction (150 °C) while maintaining the temperature of the FET channel at 27 °C. The 1/ f noise of the FET-type gas sensor is dominated by the carrier number fluctuation (CNF) in all operation regions. The effects of V BS on low-frequency noise (LFN) characteristics are demonstrated by the CNF model with correlated carrier mobility fluctuation. When a forward V BS of 0.5 V is applied to the sensor, the 1/ f noise decreases by the factor of ∼10 and the SNR of the sensor increases by ∼2 times compared to when a V BS of 0 V is applied. It is shown that the limit of detection (LOD) of the gas sensor for NO 2 gas can be improved from 0.55 ppb to 0.27 ppb by applying a forward V BS of 0.5 V. [ABSTRACT FROM AUTHOR]