ACS Applied Electronic Materials

Journal: ACS Applied Electronic Materials

Abbreviation

ACS Appl. Electron. Mater.

Publisher

American Chemical Society

ISSN

2637-6113

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Publications 1 - 10 of 10

Termination-Dependent Resistive Switching in SrTiO3 Valence Change Memory Cells
Mladenović, Marko; Kaniselvan, Manasa; Weilenmann, Christoph; et al. (2025)
ACS Applied Electronic Materials
Valence change memory (VCM) cells based on SrTiO3 (STO), a perovskite oxide, are a promising type of emerging memory device. While the operational principle of most VCM cells relies on the growth and dissolution of one or multiple conductive filaments, those based on STO are known to exhibit a distinctive “interface-type” switching, which is associated with the modulation of the Schottky barrier at their active electrode. Still, a detailed picture of the processes that lead to interface-type switching is not available. In this work, we use a fully atomistic ab initio model to study the resistive switching of a Pt-STO-Ti stack. We identify that the termination of the crystalline STO plays a decisive role in the switching mechanism, depending on the relative band alignment between the material and the Pt electrode. In particular, we show that the accumulation of oxygen vacancies at the Pt side can be the origin of resistive switching in TiO2-terminated devices by lowering the conduction band minimum of the STO layer, thus facilitating transmission through the Schottky barrier. Moreover, we investigated the possibility of filamentary switching in STO and revealed that it is most likely to occur at the Pt electrode of the SrO-terminated cells.
Buried In-Plane Ferroelectric Domains in Fe-Doped Single-Crystalline Aurivillius Thin Films
Campanini, Marco; Trassin, Morgan; Ederer, Claude; et al. (2019)
ACS Applied Electronic Materials
Ferroelectric Thin Films for Oxide Electronics
Müller, Marvin; Efe, Ipek; Sarott, Martin F.; et al. (2023)
ACS Applied Electronic Materials
Ferroelectric materials have set in motion numerous ultralow-energy-consuming device concepts that can be integrated into state-of-the-art complementary metal–oxide–semiconductor technology. Their nonvolatile, spontaneous electric polarization makes them promising candidates to control functionalities at the nanoscale with energy-efficient electric fields only. In this spotlight article, we start with a brief introduction to ferroelectric materials, the challenges involving the design of thin films and review the state-of-the-art of their integration into various electronic applications. Revolutionary in situ and operando diagnostic tools allowing the monitoring of the technology-relevant polarization state during the material design, or its operation will be detailed. Concepts such as chiral states in ferroelectrics and neuromorphic-type switching will be addressed to provide a comprehensive view on the evolution of ferroelectric states for the next generation of low-energy-consuming electronics. Finally, we discuss the most recent developments in the field, including the emergence of ferroelectricity at the nanoscale and in two-dimensional systems.
Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces
Wang, Adam; Jung, Doohwan; Lee, Dongwon; et al. (2021)
ACS Applied Electronic Materials
Electrode-to-cell/tissue interfaces with high biocompatibility, low impedance, and long-term chemical and mechanical stability are of paramount importance in numerous biological and biomedical applications. For meticulous monitoring of biological parameters, there is a rapidly growing interest in sensing at subcellular levels with radically improved spatiotemporal resolution, which necessitates ultra-miniaturized electrodes with significant reduction in electrode contact sizes. Such aggressive electrode downsizing inevitably impacts the electrochemical interfaces, with the consequences still poorly understood. This paper reports the first systematic analysis of the interfacial electrochemical impedance spectroscopy of electrodes comprising a variety of biocompatible electrode materials consisting of gold (Au), platinum (Pt), indium tin oxide, and titanium nitride (TiN) coated with/without an organic polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with electrode diameters (D) ranging from millimeter to subcellular (<10 μm) dimensions. PEDOT:PSS-coated electrodes have greater Faradaic charge-transfer capability and capacitive coupling compared to their uncoated counterparts. At D = 10–200 μm, the PEDOT:PSS coating reduces the electrode interfacial impedance at 1 kHz by up to ×10(1.6), while at D > 200 μm, the effect is lessened due to the dominance of solution, or bulk electrolyte, and routing resistance. The low interfacial impedance of PEDOT:PSS-coated electrodes makes them promising candidates for next-generation bioelectrical interfaces with subcellular spatial resolution.
Effect of Positional Disorders on Charge Transport in Nanocrystal Quantum Dot Thin Films
Xing, Yunhua; Yazdani, Nuri; Lin, Weyde M.M.; et al. (2022)
ACS Applied Electronic Materials
Understanding the impact of positional and energetic disorders in nanocrystal (NC) quantum dot thin films on charge transport is crucial to determine what to prioritize in terms of the synthesis and fabrication of these materials and to accelerate their development for electronics. Here, we computationally construct realistic NC thin films with different types of disorders and apply a density functional theory (DFT)-parameterized, kinetic Monte Carlo simulation to systematically study the effects of disorders on transport. We obtain statistics on the carrier transit pathways through the NC films and carrier residence times on individual NCs. This provides insights into the distribution of transit times across the thin films and the effective mobility. We conclude that the impact of positional disorders on charge transport depends on the type of disorder and how it affects the spacing between neighboring NCs. The formation of transport paths with short inter-NC distances can enhance mobility. Meanwhile, random packing (RP) of NCs and energetic disorders due to a distribution of NC sizes decreases mobility 2- to 4-fold. Because of the large reorganization energy of small NCs, increasing the electric field has little influence on the median residence time of a charge carrier on an NC; however, an electric field straightens the transport path of the charge carrier and reduces the average number of hops a carrier makes, which can slightly enhance mobility. Deep electronic trap states are especially detrimental to carrier mobility, particularly at low fields and when the films are otherwise highly ordered.
Probing Interfacial Magnetism in Non-Collinear Antiferromagnetic SmFeO₃ Single Crystal via Spin Hall Magnetoresistance
Xue, Mingzhu; Ding, Shilei; Li, Qixin; et al. (2025)
ACS Applied Electronic Materials
Effectively detecting the magnetization of antiferromagnetic materials and manipulating antiferromagnetic moments through all-electrical methods remain fundamental challenges. The spin Hall magnetoresistance in noncollinear antiferromagnetic systems present a promising avenue to overcome above obstacles. In this work, SmFeO₃/Pt and SmFeO₃/Cu/Pt heterostructures based on polished SmFeO₃single crystals were fabricated to probe the interfacial magnetic moment. The inserted Cu layer serves to eliminate magnetic proximity effects for SmFeO₃/Pt interface. The magnetotransport and magnetic measurements in SmFeO₃/Pt heterostructures indicate that both the spin Hall magnetoresistance and the magnetization exhibit a decrease as the temperature drops below 150 K, attributed to the emergence of magnetic ordering in Sm sublattice. The correlation in temperature dependence between the SMR and magnetization indicates that spin Hall magnetoresistance is a sensitive probe for the microscopic magnetic moments at the interfaces of antiferromagnetic insulators/heavy metal. Comparative studies on SmFeO₃/Cu/Pt heterostructures show that inserted Cu layer modifies the magnetic anisotropy of interfacial moments. Furthermore, anomalous Hall effect in SmFeO₃/Pt heterostructures exhibit sign reversal near 80 K, attributed to the competition between magnetic proximity-induced anomalous Hall effect and spin Hall effect-induced anomalous Hall effect. This study introduces the detection of interfacial magnetic moment in SmFeO₃single crystals via spin transport measurements.
Dopants and Traps in Nanocrystal-Based Semiconductor Thin Films: Origins and Measurement of Electronic Midgap States
Volk, Sebastian; Yazdani, Nuri; Yarema, Olesya; et al. (2020)
ACS Applied Electronic Materials
Recombination Dynamics in PbS Nanocrystal Quantum Dot Solar Cells Studied through Drift–Diffusion Simulations
Lin, Weyde; Yazdani, Nuri; Yarema, Olesya; et al. (2021)
ACS Applied Electronic Materials
The significant performance increase in nanocrystal (NC)-based solar cells over the last decade is very encouraging. However, many of these gains have been achieved by trial-and-error optimization, and a systematic understanding of what limits the device performance is lacking. In parallel, experimental and computational techniques provide increasing insights into the electronic properties of individual NCs and their assemblies in thin films. Here, we utilize these insights to parameterize drift–diffusion simulations of PbS NC solar cells, which enable us to track the distribution of charge carriers in the device and quantify recombination dynamics, which limit the device performance. We simulate both Schottky- and heterojunction-type devices and, through temperature-dependent measurements in the light and dark, experimentally validate the appropriateness of the parameterization. The results reveal that Schottky-type devices are limited by surface recombination between the PbS and aluminum contact, while heterojunction devices are currently limited by NC dopants and electronic defects in the PbS layer. The simulations highlight a number of opportunities for further performance enhancement, including the reduction of dopants in the nanocrystal active layer, the control over doping and electronic structure in electron- and hole-blocking layers (e.g., ZnO), and the optimization of the interfaces to improve the band alignment and reduce surface recombination. For example, reduction in the percentage of p-type NCs from the current 1–0.01% in the heterojunction device can lead to a 25% percent increase in the power conversion efficiency.
Controlling Volatility and Nonvolatility of Memristive Devices by Sn Alloying
Passerini, Elias; Lewerenz, Mila; Csontos, Miklos; et al. (2023)
ACS Applied Electronic Materials
Memristive devices have attracted significant attention due to their downscaling potential, low power operation, and fast switching performance. Their inherent properties make them suitable for emerging applications such as neuromorphic computing, in-memory computing, and reservoir computing. However, the different applications demand either volatile or nonvolatile operation. In this study, we demonstrate how compliance current and specific material choices can be used to control the volatility and nonvolatility of memristive devices. Especially, by mixing different materials in the active electrode, we gain additional design parameters that allow us to tune the devices for different applications. We found that alloying Ag with Sn stabilizes the nonvolatile retention regime in a reproducible manner. Additionally, our alloying approach improves the reliability, endurance, and uniformity of the devices. We attribute these advances to stabilization of the filament inside the switching medium by the inclusion of Sn in the filament structure. These advantageous properties of alloying were found by investigating a choice of six electrode materials (Ag, Cu, AgCu-1, AgCu-2, AgSn-1, AgSn-2) and three switching layers (SiO2, Al2O3, HfO2).
Growth of Hexagonal Delafossite CuCrO₂Thin Films via Molecular Beam Epitaxy
Schouteden, Koen; Recaman-Payo, Maria; Hsu, Wei-Fan; et al. (2025)
ACS Applied Electronic Materials
With the continuous need for faster, smaller, and more energy-efficient electronics and with traditional scaling of silicon-based semiconductor technology reaching its limits, there is a surge for materials with superior properties. Among those are functional oxides, which can have applications as a semiconductor, conductor, ferroelectric, ferromagnet, or superconductor. Within the functional oxides, quasi-2D delafossite minerals such as CuCrO₂ are of special interest since they have the potential of high hole mobility, which opens the way toward high-performance p-type thin-film transistors. In this paper, we report on the layer-by-layer growth of CuCrO₂ delafossite thin films on Al₂O₃ surfaces via atomic-oxygen-assisted molecular beam epitaxy (MBE) at growth temperatures near 700 °C. The structural quality of the epitaxial films is demonstrated by X-ray diffraction and high-resolution scanning transmission electron microscopy. Moreover, tailoring of the growth parameters in the layer-by-layer approach enables us to achieve the CuCrO₂ hexagonal phase, coexisting with the commonly reported rhombohedral CuCrO₂ phase. The flexibility and high level of control over growth conditions provided by layer-by-layer MBE offer great potential for stabilizing specific phases of the layered delafossite materials.

Publications 1 - 10 of 10

Journal: ACS Applied Electronic Materials

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