Influence of Gate Dielectric and Channel Scaling on the Low-Frequency Noise Characteristics of InGaZnO Field-Effect Transistors

In this study, we investigate the electrical and low-frequency noise (LFN) characteristics of indium–gallium-zinc-oxide (InGaZnO) field-effect transistors (FETs), focusing on the effects of gate dielectric materials and channel length scaling. Particularly, the influence of gate dielectric material on LFN was explored by comparing devices with SiO2 and Al2O3 gate dielectrics, revealing distinct differences in noise characteristics attributable to interface quality and dielectric properties. Furthermore, devices with channel lengths ranging from 10 μm down to ∼22 nm were examined, revealing a negative shift in threshold voltage and a transition in the dominant LFN mechanism with decreasing channel length. Detailed analysis shows that the noise exhibits stronger dependence on the overdrive bias as the channel length is scaled, indicating that short-channel induced excess noise mechanisms beyond simple interface trapping start to dominate. To elucidate the underlying LFN mechanisms, normalized noise levels and Hooge parameters (αH) were extracted. In short-channel devices, it was found that LFN is primarily governed by carrier number fluctuations, as indicated by a slope approaching −2 with respect to the overdrive voltage. In contrast, long-channel devices displayed a slope between −1 and −2, suggesting a hybrid mechanism involving both number and mobility fluctuations. The behavior of αH corroborated these findings, decreasing continuously with channel scaling while remaining relatively stable in long-channel devices.