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In this work, we report a planar Si-based ferroelectric field-effect transistor (FEFET) characterized by a high memory window (MW) of 4.79 V, ten-year retention, and pass disturb-free characteristics. This achievement is realized through the use of a 20-nm-thick laminated Hf $_{{0}.{5}}$ Zr0.5O2 (L-HZO) film with Al2O3 (AO)-insertion layers (ILs). The 2.4-Å-thick AO-ILs effectively severed the bulk-HZO film and scaled down each FE-thickness ( ${t}_{\text {FE}}$ ) in the L-HZO. This resulted in suppression of non-FE monoclinic phase formation to less than 10%, and more notably, an increase in the coercive field ( ${E}_{C}$ ) within the FE stack. With an increase in the number of HZO-lamination ( ${N}_{\text {HZO}}$ ), the ${E}_{C}$ was enhanced by 76% in L-HZO ( ${N}_{\text {HZO}}$ = 4) compared to single-HZO (S-HZO). This led to an increase in effective polarization ( ${P}_{\text {eff}}$ ), representing the portion of remnant polarization ( ${P}_{\text {r}}$ ) uncompensated by channel-injected charge, thereby validly influencing the threshold voltage ( ${V}_{\text {T}}$ ) shift of FEFET. The augmented ${P}_{\text {eff}}$ in L-HZO (350% increase compared to S-HZO) was directly confirmed through a more pronounced ${V}_{\text {T}}$ shift by the change of ${P}_{\text {r}}$ , which was 230% steeper in L-HZO compared to S-HZO. The revealed mechanism behind the enhanced MW and reliability in laminated-FE, stemming from the increased ${P}_{\text {eff}}$ rooted in enlarged ${E}_{C}$ , paves the way for designing the FE-stack for high-density memory or neuromorphic applications.

This study presents a material selection strategy for the interfacial layer (IL) in ferroelectric (FE) memory stacks. The nucleation-limited switching (NLS) model was applied to analyze the switching kinetics of the metal/FE/insulator/metal (MFIM) structure, where Hf0.5Zr0.5O2 (HZO) was used as the FE. Activation field ( ${E}_{a}$ ) and characteristic switching time ( $\tau $ ) were extracted for various 1-nm-thick ILs, including those of SiO2, La2O3 (LaO), AlN, and Hf3N4 (HfN). The adaptation of HZO/LaO reduced the ${E}_{a}$ by ~44% in relation to that of HZO without an IL (MFM-HZO), resulting in considerably faster switching in the low-electric-field ( ${E}$ ) region (< 4 MV $\cdot $ cm $^{-{1}}$ )—a highly suitable criterion for applications in 1-bit nonvolatile memories. In contrast, HZO/AlN showed the broadest $\tau $ distribution due to the large ${E}_{a}$ ( $\sim $ 200% of MFM-HZO), which led to the stabilization of multiple-intermediate polarization states. Promising potentiation and depression characteristics were obtained for multibit synapse applications when an incremental pulse time scheme with a step size of 10 ns was used.

Nanocomposite systems have notably improved the thermoelectric (TE) figure-of-merit ZTof organic materials; however, further studies are required to reveal the underlying TE charge transport in the heterogeneous organic system. Here, the relationship between the TE properties and the energy structure of the organic TE nanocomposite is investigated by developing different internal potential steps in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) with carbon quantum dots (CQDs) of tunable electronic bands. The charge transport across the insulating PSS layer was facilitated by embedded CQDs, which accelerated the high-energy hole transport and increased both the Seebeck coefficient and the electrical conductivity. With a carefully tuned internal potential step, PEDOT:PSS/CQD nanocomposite showed a power factor of 584 μW m–1K–2, which was 3 times larger than that of pristine PEDOT:PSS and yields a high ZT= 0.32. This work provides a fresh perspective on the energy-filtering effect for the design of high-performance organic TE nanocomposites.

With biocompatibility, biodegradability, and high functionality, silica nanoparticles (SNPs) have been widely investigated for various biomedical applications. However, lack of optical fluorescence has limited the application of SNPs as a degradable imaging agent. Here, we hydrothermally synthesized fluorescent SNPs by artificially generating optically active defect centers using tetraethyl orthosilicate and (3-aminopropyl)trimethoxysilane. The synthesized SNPs demonstrated strong blue photoluminescence originating from the dioxasilyrane (=Si(O2)) and silylene (=Si:) defect centers with the aid of aminopropyl groups. Furthermore, phosphorescence was observed at 459 nm, indicating the presence of silylene in SNPs. Finally, these SNPs have been successfully utilized as a fluorescent probe for bioimaging of normal, cancer, and macrophage cells.