Self-heating and interface traps assisted noise behavior analysis of JL-FinFET H2 gas sensor

Abstract

The aggressive scaling of conventional field-effect transistors (FET) has a pronounced detrimental impact on the signal-to-noise ratio (SNR), thereby giving rise to grave concerns about the reliability of the devices, particularly in sensor applications. This work presents a comprehensive noise and reliability analysis of the Junctionless FinFET-based hydrogen gas (H₂) sensor. The investigation considers the combined influence of flicker (F) noise and thermal noise, considering a Gaussian distribution of traps, both in the presence and absence of the self-heating effect (SHE). Using well-calibrated TCAD models, we observe a substantial 6.9 % reduction in drive current when SHE is considered. This reduction can be attributed to the intrinsic non-planar structure and the gate-wrapping effect, which leads to lower thermal conductivity. Notably, our findings demonstrate that the impact of the SHE reduces as the H₂ concentration increases from 1.0 ppm to 3.0 ppm. Furthermore, the interplay between “F” and thermal noise significantly influences the variations in drain current and noise power spectral density (PSD) as the H₂ concentration changes, keeping constant partial pressure (2.5 Pa) and ambient temperature of 300K. Noise PSD increases with rising gate voltage and trap concentration, revealing that the susceptibility to variations in PSD is more pronounced for donor traps within the subthreshold range, while it stabilizes in the saturation regime. Thus, the acquired results unveil the fact that PSD and SHE significantly influence the sensing and selectivity of the sensor, which also gets modulated with varying signal frequencies.