Unveiled Influence of Sub-gap Density of States on Low-Frequency Noise in Si-Doped ZnSnO TFTs: Does Correlated Mobility Fluctuation Model Suffice?

Abstract

The presence of low-frequency noise (LFN) in amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) is of utmost concern, prompting extensive investigations into the analysis of LFN. However, prior research endeavors have tended to overlook the significance of the sub-gap density of states (DOS) in the LFN analysis, resulting in an incomplete comprehension. To bridge this knowledge gap, the influence of sub-gap DOS is demonstrated on LFN in Si-doped ZnSnO (SZTO) thin-film transistors (TFTs) under various conditions. The SZTO TFTs is intentionally subjected to positive bias stress and hot carrier stress in order to control the sub-gap DOS and investigate how this change affects the LFN characteristics. It is revealed that the non-uniform energetic distribution of sub-gap DOS induces bias-dependent excess noise in the SZTO TFTs. Additionally, self-recovery behavior after the HCS is observed, accompanied by a commensurate reduction in 1/f noise. These empirical observations provide evidence that the conventional correlated mobility fluctuation model used to explain LFN in AOS TFTs is insufficient and underscores the critical importance of considering subgap DOS when analyzing LFN of AOS TFTs. This study investigates the low-frequency noise (LFN) characteristics of amorphous oxide semiconductor thin-film transistors (AOS TFTs). It emphasizes the importance of the non-uniform distribution of sub-gap DOS in analyzing the LFN characteristics of AOS TFTs, which proves to be more crucial than the correlated mobility fluctuation model.image