Synergistic Impact of Random Phase Distribution and Polarization Strength Variations on FeFET Across Grain Sizes and Ferroelectric Percentages

The integration of ferroelectric (FE) layers in FeFETs introduces additional sources of variability, notably random phase distribution (RPD) and polarization strength variation (PSV). This work presents a systematic TCAD-based investigation into the synergistic effects of RPD and PSV on FeFET electrical characteristics across varying grain sizes and FE material percentages. At a grain size of 20 nm, the threshold voltage (VT) variability exhibits a non-monotonic trend, peaking at 50% FE percentage with a 2.1 × increase in standard deviation compared to the 100% FE case. This is attributed to discontinuous FE paths formed at intermediate FE densities. In contrast, at a 4 nm grain size, continuous FE paths are preserved across all FE ratios, and variability is dominated by PSV, showing only a ~1.3× increase in standard deviation from 100% to 25% FE percentages. These findings highlight the critical role of accounting for both RPD and PSV in the design and optimization of FeFETs for reliable operation in in-memory computing (IMC) applications.