Observation of 1/<i>f</i>⁴ Noise in Organic Bilayer Ambipolar FETs and Proposition of Defect Engineering Method for Ultimate Noise Control

Abstract The omnipresence of low‐frequency noise (LFN) within semiconductor materials and devices poses a substantial concern for the reliability of integrated circuits (ICs). Consequently, considerable research endeavors are directed toward characterizing LFN across various types of field‐effect transistors (FETs), pivotal components in IC. Here, the LFN characteristics of bilayer ambipolar FETs based on organic semiconductors are investigated, / uri / We report that interface defects at the n/p junctions engender a correlation between trapping/detrapping noise and generation/recombination noise, resulting in a 1/ f 4 noise. The elucidation of this distinctive noise behavior is conducted through comprehensive and comparative studies on LFN of single n‐ and p‐channel FETs. Furthermore, a novel approach is proposed to control excess noise in bilayer ambipolar FETs by inserting a thin insulator layer (parylene) between the n/p junction. This yields a notable reduction in noise amplitude, concurrently leading to the dissolution of 1/ f 4 noise into 1/ f 3 and 1/ f 2 components. This study not only furnishes the inaugural report of the underlying mechanism behind the unique 1/ f 4 noise but also presents a pragmatic strategy for its control, thereby opening a new horizon for LFN studies on organic‐based FETs.