Effects of Channel Length Scaling on the Signal-to-Noise Ratio in FET-Type Gas Sensor With Horizontal Floating-Gate

Abstract

We investigate the channel length (L) scaling effects on the signal-to-noise ratio (SNR) of the field-effect-transistor (FET)-type gas sensor with a horizontal floating-gate. A sensing layer, 15 nm of indium-gallium-zinc-oxide thin film, is deposited by the radio frequency sputtering method. Nitrogen dioxide is used as a target gas. The low-frequency noise characteristics of the FET-type gas sensor are explained by the carrier number fluctuation model with correlated mobility fluctuation. The SNR is proportional to the square root of the Lof the FET transducer. The result provides important guidelines in designing the sensor platform in FET-type gas sensors.