Alkali-metal incorporation in transition-metal oxides is an effective approach for improving electrochemical charge-storage behavior. In this work, Na-ion-incorporated manganese oxide was synthesized via a low-cost chemical precipitation route and systematically examined for its structural, morphological, and electrochemical properties. X-ray diffraction confirmed the Mn2O3 and NaMnO2 phases, while FTIR spectra revealed characteristic Mn-O vibrational modes. SEM and EDS investigations demonstrated granular morphology and successful Na incorporation. Electrochemical measurements carried out in a three-electrode configuration using 1 M KOH electrolyte showed a significant enhancement in capacitive performance upon Na incorporation. The specific capacitance increased from 74.54 F g(-1) for Mn2O3 to 401.9 F g(-1) at 2 mV s(-1). Furthermore, a symmetric Swagelok-type supercapacitor based on NaMnO2 delivered a specific capacitance of 52.98 F g(-1) with an energy density of 128.83 Wh kg(-1) at a power density of 2000 kg(-1), retaining similar to 75% capacitance after 10,000 cycles.

The correlations among the Bi stoichiometry, secondary phase formation, electronic structure, and electrochemical behaviour have been established in sol-gel auto-combustion prepared Bi1+xFeO3 (x = 0.00-0.10) nanocrystals. A quantitative phase analysis, from Rietveld refined X-ray diffraction (XRD) patterns, conveyed a minimum secondary phase segregation, similar to 4.1 %, in Bi1.05FeO3. The Bi3+ and Fe3+ ions have been confirmed in the Bi1+xFeO3 samples through Fe L-edge and Bi N-edge X-ray absorption spectroscopy (XAS) spectra. The O K-edge XAS spectra indicated a reduction in unoccupied Bi 6sp states and, thus, endorsed the band gap energy decrease, from 2.1 eV to 1.93 eV, and oxygen ion vacancy formation. Electrochemical studies revealed that Bi1.05FeO3 exhibited the highest capacitance of 222.2 F/g and 117.3 F/g in 1 M KOH and 1 M NaOH electrolytes, respectively. An asymmetric supercapacitor device, a Swagelok cell (Bi1.05FeO3//activated carbon, 1 M KOH), has offered a high energy density of 124.9 Wh/kg (at a power density of 1750 W/kg) with 88 % capacitance retention after 10,000 cycles.

ABSTRACT The lack of high‐performance p‐type channel materials that can be processed at low temperatures has hindered the progress of monolithic 3D integration. Despite its high hole mobility, Te often exhibits discontinuous island‐like growth when deposited using atomic layer deposition (ALD) due to its weak surface interactions. This study introduces a new reductive transformation method that addresses this inherent issue by converting continuous ALD‐grown TeO 2 films into crystalline, impurity‐free Te layers. Notably, this approach allows for the formation of fully continuous Te films, even at thicknesses below approximately 5 nm. By utilizing a TeH 2 ‐assisted reduction pathway generated in situ, this self‐limiting process ensures complete removal of oxygen from both the bulk and interface regions while preserving exceptional conformality in structures with high aspect ratios. The resulting Te films exhibit excellent electrical properties, such as low contact resistance and stable switching in nonplanar transistor configurations. By decoupling the film continuity from surface wettability, this chemical transformation approach provides a breakthrough solution for integrating ultrathin p‐type chalcogenides into advanced back‐end‐of‐line architectures.

The crystal and domain structures of epitaxial polymorphic oxide thin films are governed not only by intrinsic bulk energies but also by extrinsic factors arising from interactions with the underlying oxide substrates. Here, we investigate the effects of substrate miscut on the phase stability of epitaxial HfO2 films on yttria-stabilized zirconia (Y:ZrO2, YSZ), employing a combined experimental and computational approach to map the thickness-temperature phase diagram. High-quality epitaxial 6% Y-doped HfO2 films with atomically smooth surfaces were fabricated by magnetron sputtering on both nominally-flat and 8°-miscut (001) YSZ single-crystal substrates. On nominally-flat substrates, (100)-oriented orthorhombic films form a two-variant domain structure and evolve into (001)-oriented monoclinic phases at larger thicknesses. On 8°-miscut substrates, in contrast, a (100)-oriented orthorhombic phase with a preferential population among the two variants is stabilized at small thicknesses, whereas a reoriented, (100)-oriented monoclinic phase is favored at larger thicknesses, accompanied by a pronounced narrowing of the orthorhombic stability window. This work provides fundamental insight into the control of phase stability and domain architecture in polymorphic oxides, relevant to the integration of complex oxides in advanced electronic platforms.

Ru is a promising material for ultrathin interconnects and capacitor electrodes. However, achieving ultrathin, continuous metallic films with minimal surface roughness remains challenging in atomic layer deposition (ALD) due to nucleation limitations on dielectric surfaces. In this study, we demonstrate an ALD process for Ru films using a tricarbonyl(trimethylenemethane)ruthenium [Ru(TMM)(CO)3] precursor and O3. The O3-based process at 220 °C exhibits a high growth per cycle of 0.17 nm/cycle with a negligible incubation period on SiO2. In particular, electrical continuity is achieved even at sub-nanometer thicknesses, indicating a high nucleation density and effective suppression of island coalescence. This leads to ultra-smooth surface morphology even as the film scales toward practical thicknesses. Furthermore, we identify that phase evolution is critically governed by the O3 exposure conditions. High O3 flow rates suppress film growth associated with the formation of volatile species such as RuO4, whereas extended pulse durations at moderate fluxes promote progressive oxidation to RuO2. These findings demonstrate that phase evolution is governed not only by the total oxidant dose but also by the oxidant supply conditions, providing a strategy for controlling nucleation, surface morphology, and phase in Ru-based ALD.

In this study; the effect of nominal Ca/P ratios has been investigated to build a relationship among the synthesis, structural, compositional, thermal stability, and electronic structure assets of calcium phosphate phases. The insitu and ex-situ X-ray diffraction (XRD) measurements and quantitative phase analysis are performed to investigate the structural phase evolution and transformation under heat treatment. The low-temperature (80 degrees C) synthesis employed in this work has resulted in calcium-deficient hydroxyapatite (CDHA; pentacalcium dihydrogen-phosphate tris-phosphate hydroxide) phase formation for all the nominal Ca/P ratios (1.4-1.8). It is evidenced that the single phase beta-Ca3(PO4)2 (beta-tricalcium diorthophosphate; beta-TCP) is stabilized for nominal Ca/ P = 1.4 at 1000-1100 degrees C. The in-situ and ex-situ XRD results revealed that the Ca10(PO4)6(OH)2 (i.e., hydroxyapatite; HA) and beta-TCP are the stable phases in the nominal Ca/P ratios of 1.5 and 1.6 containing samples. In the intermediate Ca/P ratios range (i.e., 1.67-1.7), the tri-phasic calcium phosphates (beta-TCP, HA, and alpha-TCP) have been stabilized. Excitingly, the significant proportion of the alpha-TCP phase has been stabilized along with the dominating HA phase, at higher nominal Ca/P ratios (1.8). FE-SEM results show porous morphology, despite the nominal Ca/P ratio variation. The phase identification and dissimilarity in the O 2p and Ca 3d orbital hybrid-ization, in the various phases of calcium phosphate, is also investigated by employing the element-specific X-ray absorption near edge structure (XANES) at O K-edge and Ca L-edge.

The lack of high-performance p-type channel materials that can be processed at low temperatures has hindered the progress of monolithic 3D integration. Despite its high hole mobility, Te often exhibits discontinuous island-like growth when deposited using atomic layer deposition (ALD) due to its weak surface interactions. This study introduces a new reductive transformation method that addresses this inherent issue by converting continuous ALD-grown TeO2 films into crystalline, impurity-free Te layers. Notably, this approach allows for the formation of fully continuous Te films, even at thicknesses below approximately 5 nm. By utilizing a TeH2-assisted reduction pathway generated in situ, this self-limiting process ensures complete removal of oxygen from both the bulk and interface regions while preserving exceptional conformality in structures with high aspect ratios. The resulting Te films exhibit excellent electrical properties, such as low contact resistance and stable switching in nonplanar transistor configurations. By decoupling the film continuity from surface wettability, this chemical transformation approach provides a breakthrough solution for integrating ultrathin p-type chalcogenides into advanced back-end-of-line architectures.

Achieving phase-pure Zintl alloys containing volatile elements remains a critical challenge due to their high reactivity, low melting points, and strong vapor pressures. In this work, we present a strategy for synthesizing single-phase alkali-metal-incorporated ZnSb alloys, focusing on 1-1-1 type Zintl compounds. Conventional solid-state reactions are often compromised by secondary phase formation and surface oxidation. To address these issues, we established a refined two-step process to synthesize bulk phase-pure LiZnSb, and further developed a three-step process to address the challenges associated with potassium, thereby achieved bulk phase-pure KZnSb. Air stability tests further demonstrate that the three-step process significantly suppresses surface oxidation in KZnSb compared with conventional approaches. This work offers an effective strategy for stabilizing alkali-metal-based thermoelectric materials and provides a foundation to design next-generation Zintl-phase materials for high-efficiency energy harvesting applications.

Two-dimensional (2D) layered Zintl compounds have emerged as promising candidates for thermoelectric applications due to their favorable electronic structures, efficient charge transport pathways, and loosely bound cations. In this study, we engineered 2D-layered structures in polycrystalline ZnSb through alkali metal (A = Li, Na, K) alloying, inducing a bonding transition from sp(3) to sp(2) hybridization that promotes the formation of layered structures. Structural analysis confirmed the formation of layered phases, with increasing texturing fractions from Li to K. Electrical transport measurements revealed that LiZnSb exhibited high electrical conductivity (similar to 6561 S cm(-1)) due to a high carrier concentration, while NaZnSb showed moderate conductivity (similar to 213 S cm(-1)) with a carrier concentration close to the theoretical value (7.38 x10(18) cm(-3)). In contrast, KZnSb demonstrated extremely low conductivity, hindering reliable carrier concentration analysis. As a result, NaZnSb achieved a maximum ZT of 0.079 at 375 K, which is significantly higher than that of LiZnSb. The single parabolic band (SPB) model suggests that NaZnSb may be further optimized through extrinsic doping at the Zn site, whereas LiZnSb remains limited by intrinsic cation deficiencies. These results demonstrate that alkali metalinduced bonding transitions offer a viable strategy for engineering 2D structures in Zintl compounds to enhance thermoelectric performance.

Chiral quantum magnets with spin-states separated by a large energy gap are technologically attractive but difficult to realize. Geometrically frustrated topological states with nanoscale chirality may offer a chemical pathway to such materials. However, room temperature spin misalignment, weakness of Dzyaloshinskii-Moriya interactions, and high energy requirements for lattice distortions set high physicochemical barriers for their realization. Here, we show that layered iron oxyhydroxides (LIOX) address these challenges due to chirality transfer from surface ligands into spin-states of dimerized FeO6 octahedra with zig-zag stacking. The intercalation of chiral amino acids induces angular displacements in the antiferromagnetic spin pairs with a helical coupling of magnetic moments along the screw axis of the zig-zag chains, or helical spin-ladders. Unlike other chiral magnets, the spin states in LIOX are chemically and optically accessible, they display strong optical resonances with helicity-matching photons and enable spin-selective charge transport. The static rather than dynamic polarization of spin ladders in LIOX makes them particularly suitable for catalysis. Room-temperature spin pairing, field-tunability, environmental robustness, and synthetic simplicity make LIOX and its intercalates a uniquely practical family of quantum magnets.

Achieving uniform dopant distribution and fine compositional tuning in atomic layer deposition (ALD) processes remains a significant challenge, particularly for ultrathin films, due to their cyclic nature. This study systematically investigates the inherent limitations of compositional uniformity and the minimum thickness achievable in depositing doped films using ALD. Furthermore, a strategy is implemented to resolve the compositional nonuniformity in the ALD-grown doped films by employing inhibitors. Utilizing Sn-doped In2O3 films as the model system, this approach examines the influences of carboxylic acids, including acetic acid, isobutyric acid, and 2-ethylbutyric acid, as inhibitors, resulting in a significant reduction of the growth per cycle of a SnOx doping layer to 1/10 to 1/20 of the levels observed without inhibitors. The degree of inhibition correlates with the size of the carboxylic acid, allowing precise control over dopant composition and enabling uniform doping in films as thin as 2 nm. Also, atomistic simulations reveal that steric hindrance plays as the major inhibition mechanism among the carboxylic acids, providing mechanistic insights into the design criteria for optimal inhibitors. The results suggest that inhibitor-assisted ALD processes offer a viable pathway to improve dopant control and alleviate thickness limitations, enhancing the performance of advanced materials.

Connections among the metal-oxygen octahedra distortions, electronic structure perturbation and origin of photoluminescence (PL) in aliovalent element (Zn2+) doped SnO2 thin films have been investigated using the near edge X-ray absorption fine structure (NEXAFS) spectroscopy, PL spectroscopy, UV-visible absorption spectroscopy, and X-ray diffraction (XRD). The crystallite increases and the bandgap energy decreases with increasing the annealing temperature. Sn M5,4 edge and Zn L3,2-edge NEXAFS spectra have confirmed the Sn4+ and Zn2+ ions in thin films. O K-edge NEXAFS spectra convey Sn-O6 distortion. Mechanistically, different oxygen vacancies (VO0, V+1

The high surface energy of metals often drives the formation of isolated ultrathin islands of metal nuclei during film fabrication, which remains a significant challenge in achieving continuous, smooth metallic films. This study introduces an inhibitor-modified atomic layer deposition (ALD) strategy for producing ultrathin continuous Ir and Pt films on dielectric substrates. Aniline, which was used as the inhibitor, was exclusively adsorbed onto the metallic surface. The selective passivation of metal nuclei with aniline suppresses the lateral growth of existing nuclei while promoting the formation of new nuclei, enabling the formation of continuous films with thicknesses below 1 and 2.3 nm for Ir and Pt, respectively. Compared with conventional ALD, this approach significantly improved the surface smoothness and reduced the resistivity. Furthermore, this approach is particularly effective for precursors with substantial nucleation delays. This strategy offers an effective solution for fabricating ultrathin and smooth metallic films for emerging electronic devices.

Metastable materials possess unique properties critical for advanced technologies; however, their synthesis is significantly challenging. Among the TiO2 polymorphs, rutile TiO2 stands out for its exceptional dielectric properties; however, its film growth typically requires high-temperatures or lattice-matched substrates, limiting its practical applications. This article presents a novel sacrificial layer strategy for the atomic layer deposition (ALD) of pure-phase rutile TiO2 films on diverse substrates, including amorphous Al2O3, HfO2, and ZrO2. This approach employs ultrathin Ru sacrificial layers to facilitate the formation of rutile TiO2 seed layers via the in situ generation of a rutile-matched RuO2 lattice. At the same time, it is completely removed as volatile RuO4 under exposure to O3 during the ALD process. This approach eliminates the need for high-temperature annealing and substrate restrictions, enabling low-temperature formation of rutile TiO2 on diverse substrates, including amorphous oxides. Comprehensive characterization reveals the structural stability of the films and their enhanced dielectric performance. Stabilizing rutile TiO2 independently of the underlying layer opens new possibilities for its integration into memory capacitors. Furthermore, this strategy provides a versatile framework for stabilizing other metastable material phases, thereby offering opportunities for diverse applications.

Correlations among the restacking tendency of MXenes' 2D layers, encapsulation of 2D MXenes with metal-oxide nanostructures, the effect of alkali metal loading, and electrochemical activities of MXenes are matters of debate and involve a deep understanding of their functionality and pseudocapacitive properties. Herein, MXene sheets were encapsulated with SnO2 and Na-SnO2 nanoparticles (NPs) and investigated for their structural, electronic, surface morphological, and electrochemical properties. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed the formation of MXenes and SnO2-based nanocomposite architectures. X-ray absorption spectroscopy (XAS) measurements, measured at the Sn M-edge and Ti L-edge, confirmed the presence of Sn4+ and Ti4+ ions in SnO2@MXene and/or Na-SnO2@MXene nanocomposites. A low concentration (similar to 1%) of Na loading in SnO2 NPs or SnO2@MXene nanocomposites facilitated supplementary redox features and, thus, offered nearly two times higher specific capacitance values than their bare counterparts. The log scan rate vs log peak current graphs unveiled a dominating surface-related charge storage mechanism in bare SnO2 NPs. Na loading enabled an appreciable diffusion-controlled charge storage mechanism, surface-related charge storage in the Na-SnO2@MXene nanocomposites, and a specific capacitance of 91.2 F g-1 at a scan rate of 5 mV s-1. The three-electrode cell of Na-SnO2@MXene nanocomposites exhibited similar to 89% retention for 3000 cycles. A two-electrode-based symmetric supercapacitor device, a Swagelok cell, was tested for the Na-SnO2@MXene sample with 1 M KOH electrolyte and 2 V LED. The symmetric supercapacitor offered a high energy density of similar to 75 W h kg-1 (at a power density of 7500 W kg-1) and a high-power density of 27 000 W kg-1 (at an energy density of 30 W h kg-1).

Ultrathin Pt films have attracted interest for use in advanced microelectronics. However, the reaction chemistry between Pt precursors and reactants for atomic layer deposition (ALD) remains underexplored. Herein, we examine the ALD process of Pt films using dimethyl(N,N-dimethyl-3-butene-1-amine-N)platinum (DDAP) precursor and O-3. Despite the absence of self-limiting growth behavior, this method demonstrates high growth per cycle and produces high-quality films across a broad temperature range of 180-280 degrees C. The Pt films exhibited extremely low impurity levels, including carbon, nitrogen, hydrogen, and oxygen, as confirmed by secondary-ion mass spectrometry; this resulted in a low bulk resistivity of approximately 11 mu Omegacm, close to the theoretical value of Pt. The nucleation behavior strongly depended on the substrate and temperature. Higher temperatures reduced the incubation cycle and film roughness, particularly on Al2O3 substrates, facilitating more favorable nucleation compared to SiO2 because of its higher surface energy. Consequently, the minimum thickness required for continuous film formation decreased from similar to 5 nm for SiO2 to similar to 3 nm for Al2O3. These improvements also delayed the onset of the thickness-dependent resistivity increase in Al2O3. Our findings highlight the potential of the DDAP-O-3 process to fabricate ultrathin, continuous Pt films suitable for next-generation microelectronic applications that demand nanoscale metal layers.

Correlations among the restacking tendency of MXenes’ 2D layers, encapsulation of 2D MXenes with metal–oxide nanostructures, and the effect of alkali metal loading are investigated for pseudocapacitive properties.

SrTiO3 (STO), which has an exceptionally high dielectric constant, is a promising candidate for capacitor dielectrics for dynamic random-access memory (DRAM) applications. However, during atomic layer deposition (ALD), unwanted interfacial reactions with substrates, such as Ru, hinder its integration, which results in compositional nonuniformity and poor crystallinity. In this study, an ultrathin Pt layer (<= 1 nm) is introduced as a reaction barrier, which effectively suppresses these interfacial reactions. This approach enabled the growth of high-quality stoichiometric STO films with enhanced crystallinity and dielectric performance. Despite its sub-nanometer thickness, the Pt layer notably improved the compositional uniformity and promoted film crystallization, which significantly increased the dielectric constants and reduced the equivalent oxide thickness (EOT). Post-deposition annealing (PDA) at 500 degrees C, compatible with DRAM fabrication, yielded an EOT of 0.34 nm with stable leakage currents and long-term reliability for STO films thinner than 10 nm. Furthermore, the area-selective growth characteristic of the ultrathin Pt layer eliminated the critical etching challenges of Pt, which facilitated selective growth on Ru and avoided unwanted growth on dielectric materials such as SiO2. This study presents a scalable, low-temperature solution for integrating STO into DRAM capacitors, thereby addressing critical fabrication challenges and advancing the potential of STO in memory applications.