Scanning droplet cell microscopy on a wide range hafnium–niobium thin film combinatorial library

Mardare, Andrei Ionut; Ludwig, Alfred; Savan, Alan; Hassel, Achim Walter

doi:10.1016/j.electacta.2013.03.065

Cited by 25 publications

(31 citation statements)

References 33 publications

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“…Slightly elongated surface grains, with about 100 nm equivalent diameter, are grouped in domains for high Nb amounts and almost equal Hf and Ta concentrations. This type of microstructure has previously been observed in both Nb–Ta and Hf–Nb binary thin film libraries (for Nb amounts around 66 at.%) which indicate that surface domains formation may be triggered by the presence of Nb [23,24]. Additionally, the study of a Hf–Ta binary library revealed that amorphisation of alloys occurs at equal amounts of Hf and Ta [25].…”

Section: Resultssupporting

confidence: 61%

“…The transition between hexagonal Hf and tetragonal Ta occurs through a relatively large amorphous compositional zone. However, mixing the cubic phase of Nb with either tetragonal Ta or hexagonal Hf results in very narrow amorphous regions, as binary studies have shown [23,24]. Depending on the composition, the transitions between cubic and either tetragonal or hexagonal phases are sharp.…”

Section: Resultsmentioning

confidence: 99%

“…The highest oxide formation factor was measured for alloys with the highest Nb and lowest Ta concentrations. These trends can be understood when the oxide formation factors reported for the anodisation of pure Hf, Nb and Ta in acetate buffer electrolyte (2.30, 2.60 and 1.80, respectively) are considered [23–25]. The highest amount of Ta in the library, where the smallest factor for the ternary alloys was identified, coincided with the lowest amounts of Hf and Nb.…”

Section: Resultsmentioning

confidence: 99%

“…This relationship is defined mainly by the highest amount of Ta present in this region, since both Hf and Ta pure oxides have much lower permittivities than to Nb oxides (19 and 22 vs . 52) [23–25]. However, the permittivity mapping of the library is also directly affected by the measured oxide thickness values (the measured capacitance is inversely proportional to the thickness).…”

Section: Resultsmentioning

confidence: 99%

“…Anodisation of binary thin film combinatorial libraries containing Hf, Nb or Ta has already revealed very interesting features. Screening of a Hf–Nb library showed the effect of Nb as a cubic phase stabiliser in metallic alloys and a remarkably high electrical permittivity of mixed Hf–Nb anodic oxides [23]. Semiconducting properties of Nb 2 O 5 were imprinted on mixed oxides grown anodically on Nb–Ta combinatorial libraries, with relatively high charge carrier densities, while the dielectric constants remained at high values [24].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system

Mardare

Kollender

et al. 2018

Science and Technology of Advanced Materials

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A thin film combinatorial library deposited by co-sputtering of Hf, Nb and Ta was employed to characterise fundamental properties of the Hf-Nb-Ta system. Compositional mappings of microstructure and crystallography revealed similarities in alloy evolution. Distinct lattice distortion was observed upon addition of hexagonal Hf, leading to amorphisation of alloys containing more than 32 at.% Hf and less than 27 and 41 at.% Nb and Ta, respectively. Volta potential and open circuit potential mappings indicated minimal values for the highest Hf concentration. Localised anodisation of the library by scanning droplet cell microscopy revealed valve metal behaviour. Oxide formation factors above 2 nm V−1 were identified in compositional zones with high amounts of Nb and Ta. Fitting of electrochemical impedance spectroscopy data allowed electrical permittivity and resistivity of mixed oxides to be mapped. Their compositional behaviours were attributed to characteristics of the parent metal alloys and particularities of the pure oxides. Mott–Schottky analysis suggested n-type semiconductor properties for all Hf–Nb–Ta oxides studied. Donor density and flat-band potential were mapped compositionally, and their variations were found to be related mainly to the Nb amount. Synergetic effects were identified in mappings of Hf-Nb-Ta parent metals and their anodic oxides.

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Section: Resultssupporting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system

Mardare

Kollender

et al. 2018

Science and Technology of Advanced Materials

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Cutting Edge High‐Throughput Synthesis and Characterization Techniques in Combinatorial Materials Science

Tan,

Wu,

Yang

et al. 2024

Adv Materials Technologies

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The Materials Genome Initiative is expected to accelerate the materials discovery and design by fundamentally changing the trial‐and‐error research paradigm. However, mass data from high‐throughput experiments is still essential for the revelation of rules and verification of theories. In fact, the development of combinatorial materials science is always on the strength of the upgrade and evolution of high‐throughput techniques in each stage, especially high‐throughput materials synthesis and characterization. Herein, this review summarizes the high‐throughput synthesis methods for combinatorial materials libraries, especially the co‐deposition and masking techniques of thin‐film fabrication; and details the high‐throughput characterization methods for specific material properties and typical material categories, which comes down to the spectroscopy and microscopy techniques. It is considered that high‐throughput concepts will be the predominant lab experimentation in the future, along with advanced experimental techniques and convenient data processing procedures. Before that, more cooperation between multiple researchers from different fields should be conducted to complete the combinatorial materials research, since the high‐throughput technology covers multiple disciplines with a huge span.

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Electrochemical Oxidation of Hf–Nb Alloys as a Valuable Route to Prepare Mixed Oxides of Tailored Dielectric Properties

Zaffora

Quarto

Kura

et al. 2018

Adv Elect Materials

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Metal oxides with high dielectric constant are extensively studied in the frame of substituting SiO2 as gate dielectric in nanoelectronic devices. Here, high‐k mixed HfO2/Nb2O5 oxides are prepared by a facile electrochemical route starting from sputtering‐deposited Hf–Nb alloys with several compositions. Transmission electron microscopy, grazing incidence X‐ray diffraction, and glow discharge optical emission spectroscopy are employed to study the oxide structures, disclosing a crystalline–amorphous transition of the electrochemically prepared oxides by increasing the Nb content. Photo‐electrochemical measurements allow the observation of optical transitions ascribed to localized states inside oxide bandgap induced by the presence of oxygen vacancies for Hf‐rich oxides. Impedance measurements, coupled with withstand voltage and leakage current estimates, provide a comprehensive view of the real dielectric properties of the oxides. The highest ε is estimated for the anodic oxide grown on Hf–39 at% Nb (i.e., 45) but thin film grown on Hf–57 at% Nb alloy shows the best dielectric properties, revealing high dielectric constant, high withstand voltage, and low leakage current. Promising equivalent oxide thickness (down to 0.38 nm) is estimated for the oxide thin layers. The electrochemical oxidation represents a valuable and reliable way to prepare high‐k thin oxide films with tailored and controlled dielectric properties.

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Scanning droplet cell microscopy on a wide range hafnium–niobium thin film combinatorial library

Cited by 25 publications

References 33 publications

Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system

Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system

Cutting Edge High‐Throughput Synthesis and Characterization Techniques in Combinatorial Materials Science

Electrochemical Oxidation of Hf–Nb Alloys as a Valuable Route to Prepare Mixed Oxides of Tailored Dielectric Properties

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