Special Issue "Nanometrology"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (30 September 2021) | Viewed by 6112

Special Issue Editor

Dr. Petr Klapetek
E-Mail Website
Guest Editor
1) Department of Nanometrology, Czech Metrology Institute, Brno, Czech Republic
2) CEITEC, Brno University of Technology, Brno, Czech Republic
Interests: metrology; scanning probe microscopy; instrumentation; data processing

Special Issue Information

Dear Colleagues,

Thanks to advances in nanoscience and nanotechnology and increasing use of their research outputs in real products, there is an increasing need for reliable measurement techniques. Nanometrology is a rapidly evolving area of measurement focusing on characterization of nanostructures and nanomaterials. It includes a wide variety of analytical methods that can be applied to samples used in nanotechnology, typically being based on methods that have very high spatial resolution and can measure local physical quantities or chemical composition. A key aspect of nanometrology is to make these measurements reliable and metrologically traceable. This is a challenge in many areas as the measurement methods often represent state-of-the-art in sensing, and establishing metrological traceability can be a very complex task. As nanomaterials are one of the key scientific areas and products of nanoscience and nanotechnology and as many of the nanometrology methods are therefore focused on them, I am pleased to announce this Special Issue of Nanomaterials concentrating on this topic.

Dr. Petr Klapetek
Guest Editor

Manuscript Submission Information

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Keywords

  • Dimensional and other physical parameters measurements in nanoscience and nanotechnology
  • Analytical methods with nanoscale resolution
  • Emerging measurement techniques
  • Analysis of nanoparticles and nanocomposites
  • Metrological traceability at nanoscale

Published Papers (6 papers)

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Research

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Article
Traceable Nanoscale Measurements of High Dielectric Constant by Scanning Microwave Microscopy
Nanomaterials 2021, 11(11), 3104; https://doi.org/10.3390/nano11113104 - 17 Nov 2021
Viewed by 645
Abstract
The importance of high dielectric constant materials in the development of high frequency nano-electronic devices is undeniable. Their polarization properties are directly dependent on the value of their relative permittivity. We report here on the nanoscale metrological quantification of the dielectric constants of [...] Read more.
The importance of high dielectric constant materials in the development of high frequency nano-electronic devices is undeniable. Their polarization properties are directly dependent on the value of their relative permittivity. We report here on the nanoscale metrological quantification of the dielectric constants of two high-κ materials, lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT), in the GHz range using scanning microwave microscopy (SMM). We demonstrate the importance of the capacitance calibration procedure and dimensional measurements on the weight of the combined relative uncertainties. A novel approach is proposed to correct lateral dimension measurements of micro-capacitive structures using the microwave electrical signatures, especially for rough surfaces of high-κ materials. A new analytical expression is also given for the capacitance calculations, taking into account the contribution of fringing electric fields. We determine the dielectric constant values εPZT = 445 and εPMN-PT = 641 at the frequency around 3.6 GHz, with combined relative uncertainties of 3.5% and 6.9% for PZT and PMN-PT, respectively. This work provides a general description of the metrological path for a quantified measurement of high dielectric constants with well-controlled low uncertainty levels. Full article
(This article belongs to the Special Issue Nanometrology)
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Article
Shape- and Element-Sensitive Reconstruction of Periodic Nanostructures with Grazing Incidence X-ray Fluorescence Analysis and Machine Learning
Nanomaterials 2021, 11(7), 1647; https://doi.org/10.3390/nano11071647 - 23 Jun 2021
Cited by 1 | Viewed by 933
Abstract
The characterization of nanostructured surfaces with sensitivity in the sub-nm range is of high importance for the development of current and next-generation integrated electronic circuits. Modern transistor architectures for, e.g., FinFETs are realized by lithographic fabrication of complex, well-ordered nanostructures. Recently, a novel [...] Read more.
The characterization of nanostructured surfaces with sensitivity in the sub-nm range is of high importance for the development of current and next-generation integrated electronic circuits. Modern transistor architectures for, e.g., FinFETs are realized by lithographic fabrication of complex, well-ordered nanostructures. Recently, a novel characterization technique based on X-ray fluorescence measurements in grazing incidence geometry was proposed for such applications. This technique uses the X-ray standing wave field, arising from an interference between incident and the reflected radiation, as a nanoscale sensor for the dimensional and compositional parameters of the nanostructure. The element sensitivity of the X-ray fluorescence technique allows for a reconstruction of the spatial element distribution using a finite element method. Due to a high computational time, intelligent optimization methods employing machine learning algorithms are essential for timely provision of results. Here, a sampling of the probability distributions by Bayesian optimization is not only fast, but it also provides an initial estimate of the parameter uncertainties and sensitivities. The high sensitivity of the method requires a precise knowledge of the material parameters in the modeling of the dimensional shape provided that some physical properties of the material are known or determined beforehand. The unknown optical constants were extracted from an unstructured but otherwise identical layer system by means of soft X-ray reflectometry. The spatial distribution profiles of the different elements contained in the grating structure were compared to scanning electron and atomic force microscopy and the influence of carbon surface contamination on the modeling results were discussed. This novel approach enables the element sensitive and destruction-free characterization of nanostructures made of silicon nitride and silicon oxide with sub-nm resolution. Full article
(This article belongs to the Special Issue Nanometrology)
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Article
Thermophysical Characterization of Efficiency Droop in GaN-Based Light-Emitting Diodes
Nanomaterials 2021, 11(6), 1449; https://doi.org/10.3390/nano11061449 - 30 May 2021
Cited by 1 | Viewed by 1007
Abstract
An efficiency droop in GaN-based light-emitting diodes (LED) was characterized by examining its general thermophysical parameters. An effective suppression of emission degradation afforded by the introduction of InGaN/GaN heterobarrier structures in the active region was attributable to an increase in the capture cross-section [...] Read more.
An efficiency droop in GaN-based light-emitting diodes (LED) was characterized by examining its general thermophysical parameters. An effective suppression of emission degradation afforded by the introduction of InGaN/GaN heterobarrier structures in the active region was attributable to an increase in the capture cross-section ratios. The Debye temperatures and the electron–phonon interaction coupling coefficients were obtained from temperature-dependent current-voltage measurements of InGaN/GaN multiple-quantum-well LEDs over a temperature range from 20 to 300 K. It was found that the Debye temperature of the LEDs was modulated by the InN molar fraction in the heterobarriers. As far as the phonons involved in the electron–phonon scattering process are concerned, the average number of phonons decreases with the Debye temperature, and the electron–phonon interaction coupling coefficients phenomenologically reflect the nonradiative transition rates. We can use the characteristic ratio of the Debye temperature to the coupling coefficient (DCR) to assess the efficiency droop phenomenon. Our investigation showed that DCR is correlated to quantum efficiency (QE). The light emission results exhibited the high and low QEs to be represented by the high and low DCRs associated with low and high injection currents, respectively. The DCR can be envisioned as a thermophysical marker of LED performance, not only for efficiency droop characterization but also for heterodevice structure optimization. Full article
(This article belongs to the Special Issue Nanometrology)
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Article
Progress in Traceable Nanoscale Capacitance Measurements Using Scanning Microwave Microscopy
Nanomaterials 2021, 11(3), 820; https://doi.org/10.3390/nano11030820 - 23 Mar 2021
Cited by 1 | Viewed by 1369
Abstract
Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a [...] Read more.
Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a detailed investigation of most possible error sources that affect the uncertainty of capacitance measurements on the reference calibration samples. We establish a comprehensive uncertainty budget leading to a combined uncertainty of 3% in relative value (uncertainty given at one standard deviation) for capacitances ranging from 0.2 fF to 10 fF. This uncertainty level can be achieved even with the use of unshielded probes. We show that the weights of uncertainty sources vary with the values and dimensions of measured capacitances. Our work offers improvements on the classical calibration methods known in SMM and suggests possible new designs of reference standards for capacitance and dielectric traceable measurements. Experimental measurements are supported by numerical calculations of capacitances to reveal further paths for even higher improvements. Full article
(This article belongs to the Special Issue Nanometrology)
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Review

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Review
Traceable Characterization of Nanomaterials by X-ray Spectrometry Using Calibrated Instrumentation
Nanomaterials 2022, 12(13), 2255; https://doi.org/10.3390/nano12132255 - 30 Jun 2022
Viewed by 142
Abstract
Traceable characterization methods allow for the accurate correlation of the functionality or toxicity of nanomaterials with their underlaying chemical, structural or physical material properties. These correlations are required for the directed development of nanomaterials to reach target functionalities such as conversion efficiencies or [...] Read more.
Traceable characterization methods allow for the accurate correlation of the functionality or toxicity of nanomaterials with their underlaying chemical, structural or physical material properties. These correlations are required for the directed development of nanomaterials to reach target functionalities such as conversion efficiencies or selective sensitivities. The reliable characterization of nanomaterials requires techniques that often need to be adapted to the nano-scaled dimensions of the samples with respect to both the spatial dimensions of the probe and the instrumental or experimental discrimination capability. The traceability of analytical methods revealing information on chemical material properties relies on reference materials or qualified calibration samples, the spatial elemental distributions of which must be very similar to the nanomaterial of interest. At the nanoscale, however, only few well-known reference materials exist. An alternate route to establish the required traceability lays in the physical calibration of the analytical instrument’s response behavior and efficiency in conjunction with a good knowledge of the various interaction probabilities. For the elemental analysis, speciation, and coordination of nanomaterials, such a physical traceability can be achieved with X-ray spectrometry. This requires the radiometric calibration of energy- and wavelength-dispersive X-ray spectrometers, as well as the reliable determination of atomic X-ray fundamental parameters using such instrumentation. In different operational configurations, the information depths, discrimination capability, and sensitivity of X-ray spectrometry can be considerably modified while preserving its traceability, allowing for the characterization of surface contamination as well as interfacial thin layer and nanoparticle chemical compositions. Furthermore, time-resolved and hybrid approaches provide access to analytical information under operando conditions or reveal dimensional information, such as elemental or species depth profiles of nanomaterials. The aim of this review is to demonstrate the absolute quantification capabilities of SI-traceable X-ray spectrometry based upon calibrated instrumentation and knowledge about X-ray interaction probabilities. Full article
(This article belongs to the Special Issue Nanometrology)
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Review
Synthetic Data in Quantitative Scanning Probe Microscopy
Nanomaterials 2021, 11(7), 1746; https://doi.org/10.3390/nano11071746 - 02 Jul 2021
Viewed by 1328
Abstract
Synthetic data are of increasing importance in nanometrology. They can be used for development of data processing methods, analysis of uncertainties and estimation of various measurement artefacts. In this paper we review methods used for their generation and the applications of synthetic data [...] Read more.
Synthetic data are of increasing importance in nanometrology. They can be used for development of data processing methods, analysis of uncertainties and estimation of various measurement artefacts. In this paper we review methods used for their generation and the applications of synthetic data in scanning probe microscopy, focusing on their principles, performance, and applicability. We illustrate the benefits of using synthetic data on different tasks related to development of better scanning approaches and related to estimation of reliability of data processing methods. We demonstrate how the synthetic data can be used to analyse systematic errors that are common to scanning probe microscopy methods, either related to the measurement principle or to the typical data processing paths. Full article
(This article belongs to the Special Issue Nanometrology)
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