Search

Abstract This study introduces a novel approach in the realm of liquid biopsies, employing a 3D Mueller-matrix (MM) image reconstruction technique to analyze dehydrated blood smear polycrystalline structures. Our research centers on exploiting the unique optical anisotropy properties of blood proteins, which undergo structural alterations at the quaternary and tertiary levels in the early stages of diseases such as cancer. These alterations manifest as distinct patterns in the polycrystalline microstructure of dried blood droplets, offering a minimally invasive yet highly effective method for early disease detection. We utilized a groundbreaking 3D MM mapping technique, integrated with digital holographic reconstruction, to perform a detailed layer-by-layer analysis of partially depolarizing dry blood smears. This method allows us to extract critical optical anisotropy parameters, enabling the differentiation of blood films from healthy individuals and prostate cancer patients. Our technique uniquely combines polarization-holographic and differential MM methodologies to spatially characterize the 3D polycrystalline structures within blood films. A key advancement in our study is the quantitative evaluation of optical anisotropy maps using statistical moments (first to fourth orders) of linear and circular birefringence and dichroism distributions. This analysis provides a comprehensive characterization of the mean, variance, skewness, and kurtosis of these distributions, crucial for identifying significant differences between healthy and cancerous samples. Our findings demonstrate an exceptional accuracy rate of over $$90\%$$ 90 % for the early diagnosis and staging of cancer, surpassing existing screening methods. This high level of precision and the non-invasive nature of our technique mark a significant advancement in the field of liquid biopsies. It holds immense potential for revolutionizing cancer diagnosis, early detection, patient stratification, and monitoring, thereby greatly enhancing patient care and treatment outcomes. In conclusion, our study contributes a pioneering technique to the liquid biopsy domain, aligning with the ongoing quest for non-invasive, reliable, and efficient diagnostic methods. It opens new avenues for cancer diagnosis and monitoring, representing a substantial leap forward in personalized medicine and oncology.

Flexible thermoelectric generators are leading candidates for next‐generation energy‐harvesting devices. Although SiGe, an environmentally‐friendly semiconductor, is the most reliable and widely tested thermoelectric material, it is difficult to form a SiGe layer with high thermoelectric performance at temperatures lower than the heat‐proof temperature of flexible plastic films. In this article, the synthesis of SiGe thermoelectric thin films via the metal‐induced layer exchange phenomenon is reviewed, from its mechanism to device performance. The selection of metal species allows low‐temperature formation (≤500 °C) of p‐ and n‐type SiGe on insulating substrates. Currently, the maximum power factors near room temperature are 850 µW m−1 K−2 for p‐type Si0.4Ge0.6 and 1000 µW m−1 K−2 for n‐type Si0.85Ge0.15. These values are the highest among those of Group IV semiconductor thin films formed at low temperatures. The flexible thermoelectric generator consisting of these p‐ and n‐type SiGe exhibits cross‐sectional and planar power densities of ≈3.0 mW cm−2 and 0.50 µW cm−2, respectively, at a temperature difference of 30 K. Finally, the future challenges of layer exchange for improving the performance of flexible thermoelectric generators based on Group IV semiconductors are discussed. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach in the realm of liquid biopsies, employing a 3D Mueller-matrix (MM) image reconstruction technique to analyze dehydrated blood smear polycrystalline structures. Our research centers on exploiting the unique optical anisotropy properties of blood proteins, which undergo structural alterations at the quaternary and tertiary levels in the early stages of diseases such as cancer. These alterations manifest as distinct patterns in the polycrystalline microstructure of dried blood droplets, offering a minimally invasive yet highly effective method for early disease detection. We utilized a groundbreaking 3D MM mapping technique, integrated with digital holographic reconstruction, to perform a detailed layer-by-layer analysis of partially depolarizing dry blood smears. This method allows us to extract critical optical anisotropy parameters, enabling the differentiation of blood films from healthy individuals and prostate cancer patients. Our technique uniquely combines polarization-holographic and differential MM methodologies to spatially characterize the 3D polycrystalline structures within blood films. A key advancement in our study is the quantitative evaluation of optical anisotropy maps using statistical moments (first to fourth orders) of linear and circular birefringence and dichroism distributions. This analysis provides a comprehensive characterization of the mean, variance, skewness, and kurtosis of these distributions, crucial for identifying significant differences between healthy and cancerous samples. Our findings demonstrate an exceptional accuracy rate of over 90 % for the early diagnosis and staging of cancer, surpassing existing screening methods. This high level of precision and the non-invasive nature of our technique mark a significant advancement in the field of liquid biopsies. It holds immense potential for revolutionizing cancer diagnosis, early detection, patient stratification, and monitoring, thereby greatly enhancing patient care and treatment outcomes. In conclusion, our study contributes a pioneering technique to the liquid biopsy domain, aligning with the ongoing quest for non-invasive, reliable, and efficient diagnostic methods. It opens new avenues for cancer diagnosis and monitoring, representing a substantial leap forward in personalized medicine and oncology. [ABSTRACT FROM AUTHOR]

Abstract Flexible thermoelectric generators are leading candidates for next‐generation energy‐harvesting devices. Although SiGe, an environmentally‐friendly semiconductor, is the most reliable and widely tested thermoelectric material, it is difficult to form a SiGe layer with high thermoelectric performance at temperatures lower than the heat‐proof temperature of flexible plastic films. In this article, the synthesis of SiGe thermoelectric thin films via the metal‐induced layer exchange phenomenon is reviewed, from its mechanism to device performance. The selection of metal species allows low‐temperature formation (≤500 °C) of p‐ and n‐type SiGe on insulating substrates. Currently, the maximum power factors near room temperature are 850 µW m−1 K−2 for p‐type Si0.4Ge0.6 and 1000 µW m−1 K−2 for n‐type Si0.85Ge0.15. These values are the highest among those of Group IV semiconductor thin films formed at low temperatures. The flexible thermoelectric generator consisting of these p‐ and n‐type SiGe exhibits cross‐sectional and planar power densities of ≈3.0 mW cm−2 and 0.50 µW cm−2, respectively, at a temperature difference of 30 K. Finally, the future challenges of layer exchange for improving the performance of flexible thermoelectric generators based on Group IV semiconductors are discussed.

The peculiarities of the surface processing of polycrystalline aluminum-nitride films on glass-ceramic and silicon substrates grown under identical conditions are considered. Aluminum-nitride films are obtained using the magnetron sputtering of a pure aluminum target (99.99%) in nitrogen–argon plasma at a magnetron power of 700 W. The consumption of working gases is 10 sccm for nitrogen and 4 sccm for argon. The film thickness is determined using a quartz resonator inside the chamber of the magnetron setup. Atomic force microscopy is used to study the surface relief of the targets before and after treatment by argon cluster ions. Small single crystallites are shown to grow on the initial surfaces, the lateral size of which is in the range of 250–550 nm. The depth of target etching by argon cluster ions is determined. Cluster ions with low energy per atom are shown to have a high efficiency of surface smoothing. A comparison of the surface morphology and surface-roughness parameters of aluminum nitride on different substrates obtained using atomic force microscopy is carried out. It is shown that aluminum nitride on silicon is smoothed more efficiently than on a glass-ceramic substrate. [ABSTRACT FROM AUTHOR]

Morphology, chemical composition, crystal structure, and magnetic circular dichroism of ZnO films doped simultaneously with Co and Al (CAZO) have been studied. The films were deposited on glass substrates by the RF magnetron sputtering of the Zn0.93Co0.05Al0.02O target. Low hydrogen concentrations of 1–4% were used in mixed Ar + H2 atmosphere together with high enough substrate temperature of 450 °C. A tendency to a decrease in the Zn amount and an increase in the relative Co and Al content in the films has been revealed in the presence of hydrogen in the atmosphere. The structural data of the studied films correlate well with those for high-hydrogenated (20–50% H2) CAZO films deposited under the same conditions and studied earlier. The new data indicate the prospect of obtaining ferromagnetic samples based on ZnO without any secondary phases. [ABSTRACT FROM AUTHOR]

One of the unique characteristics of semiconductors is the strong dependence of their properties on crystal defects and doping. However, due to the species diversity and low density, it is very difficult to control the type and concentration of the defects. In perovskite materials, crystal defects are randomly formed during the fast crystallization process, causing large heterogeneity of the samples. Here, in this work, we report a controllable method to introduce surface defects on CH3NH3PbI3 perovskite materials via the interaction with 1,4-benzoquinone (BQ) molecules on the gas and solid interface. After the adsorption of BQ molecules on the perovskite surface, surface defects can be generated by photoinduced chemical reactions. The concentration of the defects can thus be controlled by precisely regulating the laser irradiation time. The concentration of the defects can be characterized by a gradually decreased PL intensity and lifetime and was found to influence the atmospheric response and the subsequent acetone-induced degradation of the materials. These results demonstrate that crystal defects in perovskite materials can be controllably introduced, which provides a possible way to fully understand the correlation between the nature and chemical structure of these defects. [ABSTRACT FROM AUTHOR]

In this paper, we report the successful growth of 0.5BiFeO3–0.5[Formula: see text][Formula: see text]O3/SrTiO3/Si(001) heterostructure using RF-cathode sputtering in an oxygen atmosphere. The deposited films have been investigated by X-ray diffractometry and spectroscopic ellipsometry (SE). 0.5BiFeO3–0.5[Formula: see text][Formula: see text]O3 films on silicon substrates with a strontium titanate buffer layer are single-phase, polycrystalline with a texture in the 001 direction. The unit cell parameters calculated in the tetragonal approximation were [Formula: see text] = 4.005 ± 0.001 [Formula: see text]; [Formula: see text] = 3.995 ± 0.001 [Formula: see text]. The presence in the films of small unit cell deformation arising from different unit cells parameters of the film and substrate is observed. Dielectric properties and capacitance-voltage characteristics have been measured. The ellipsometric parameters have been obtained.

In this paper, we report the successful growth of 0.5BiFeO3–0.5 PbFe 0. 5 Nb 0. 5 O3/SrTiO3/Si(001) heterostructure using RF-cathode sputtering in an oxygen atmosphere. The deposited films have been investigated by X-ray diffractometry and spectroscopic ellipsometry (SE). 0.5BiFeO3–0.5 PbFe 0. 5 Nb 0. 5 O3 films on silicon substrates with a strontium titanate buffer layer are single-phase, polycrystalline with a texture in the 001 direction. The unit cell parameters calculated in the tetragonal approximation were c = 4.005 ± 0.001 Å ; a = 3.995 ± 0.001 Å. The presence in the films of small unit cell deformation arising from different unit cells parameters of the film and substrate is observed. Dielectric properties and capacitance-voltage characteristics have been measured. The ellipsometric parameters have been obtained. [ABSTRACT FROM AUTHOR]

Polycrystalline Ge thin films are promising candidates for next‐generation thin‐film transistors. However, the difficulty in Fermi‐level control due to the high density of defect‐induced acceptors has been one of the main problems for device applications. Herein, GeO2 preparation and Sn addition are combined in the advanced low‐temperature (375 °C) solid‐phase crystallization of Ge layers that have been recently developed. The GeO2 underlayer works effectively at a low Sn composition (< 4%), enlarging the grain size by a magnification of ≈5. An appropriate amount of unsubstituted Sn reduces acceptor defects and achieves a minimum hole concentration of 3 × 1016 cm−3 by combining post‐annealing (500 °C). This hole concentration is the lowest level for undoped polycrystalline Ge‐based thin films, which allows control over their Fermi level widely by impurity doping. Although the lower hole concentration provides a higher energy barrier height of the grain boundary, the hole mobility is maintained at 190 cm2 V−1 s−1 owing to the large grains (15 μm diameter). This achievement paves the way for the implementation of poly‐Ge‐based thin films in various semiconductor devices, including advanced thin‐film transistors. [ABSTRACT FROM AUTHOR]

A new grazing‐incidence diffraction (GID) measurement geometry between in plane and out of plane is proposed. It is improved from the previous ω–ϕ compensated GID in side‐inclination mode for measurement of residual stress in polycrystalline thin films [Wang & van Riessen (2017). Powder Diffr.32, S9–S15]. Instead of keeping a constant azimuthal direction of the incident beam on the thin film sample, the current proposed variation maintains a constant azimuthal direction of the scattering vector projection on the thin film sample. The variation is named 'ω–ϕ′ compensated GID in side‐inclination mode' and enables d‐spacing measurements along the same azimuthal direction. An Excel spreadsheet is included for readers to plan the measurement and to calculate the residual stress for the planned sample azimuthal direction. Anisotropic residual stresses of a polycrystalline NiFe thin film on an Si 001 substrate are measured by combining this method with phi rotations. Highly automated data analysis templates are developed using DIFFRAC.TOPAS v7 launch mode to calculate residual stress for all planned azimuthal directions sequentially. A pole figure file in simple text format is also generated from the same data set using DIFFRAC.TOPAS v7 launch mode, and can be directly imported into DIFFRAC.TEXTURE v4.1 for further texture analysis. Corrections for the incident‐beam refraction have been implemented in both data analysis models. [ABSTRACT FROM AUTHOR]

Halide perovskites are a versatile class of semiconductors employed for high performance emerging optoelectronic devices, including flexoelectric systems, yet the influence of their ionic nature on their mechanical behavior is still to be understood. Here, a combination of atomic‐force, optical, and compositional X‐ray microscopy techniques is employed to shed light on the mechanical properties of halide perovskite films at the nanoscale. Mechanical domains within and between morphological grains, enclosed by mechanical boundaries of higher Young's Modulus (YM) than the bulk parent material, are revealed. These mechanical boundaries are associated with the presence of bromide‐rich clusters as visualized by nano‐X‐ray fluorescence mapping. Stiffer regions are specifically selectively modified upon light soaking the sample, resulting in an overall homogenization of the mechanical properties toward the bulk YM. This behavior is attributed to light‐induced ion migration processes that homogenize the local chemical distribution, which is accompanied by photobrightening of the photoluminescence within the same region. This work highlights critical links between mechanical, chemical, and optoelectronic characteristics in this family of perovskites, and demonstrates the potential of combinational imaging studies to understand and design halide perovskite films for emerging applications such as photoflexoelectricity. [ABSTRACT FROM AUTHOR]

The structural, optical, and nonlinear optical absorption properties of ZnO polycrystalline thin films are investigated. Energy bandgap values are obtained with linear absorption spectrum and depending on either sole doping of Al or co‐doping, bandgap energies shift toward higher or lower energies. With Al‐only doping, bandgap of the ZnO thin film shifts toward higher energies which can be attributed to Moss–Burstein effect, and with co‐doping (Al–Cu or Al–Co) bandgap energies shift toward lower energies due to defect states residing within the bandgap. Urbach energies and grain sizes are calculated to study the effect of defect states on the nonlinear absorption, and these calculations indicate that co‐doping drastically reduces the grain size thereby increasing the contribution to the defect density by means of boundary defects. To analyze the transmission in open aperture Z‐scan data, a theoretical model incorporating one‐photon, two‐photon, and free‐carrier absorptions as well as their saturations is used. By this modeling, saturation intensity thresholds and effective nonlinear absorption coefficients are extracted from fitting of the experimental data. Highest saturation intensity threshold and effective nonlinear absorption coefficient are found for ZnO:(Al, Co) and ascribed to having the smallest bandgap energy and highest Urbach energy. [ABSTRACT FROM AUTHOR]

A growth of grain triplets is identified in vapor deposited, a -texture polycrystalline zinc oxide thin films, using a combination of transmission electron microscopy-based automated crystal orientation mapping and high-resolution imaging. Each triplet consists of three wurtzite phase grains, coordinated to near tetrahedral relative growth angles by the close-packed planes of a few nanometer diameter core of metastable zinc blende phase ZnO located at their triple junction. The triplets are aligned such that two of the grains have their fast growing 2 1 ¯ 1 ¯ 0 axes (near-) parallel to the substrate normal, and so coarsen under the principle of competitive grain growth. In contrast, growth of the third grain with a (1 0 1 ¯ 3) texture is impeded, such that it forms a small wedge between the ends of its two larger neighbors. Remarkably, all three boundaries between the grains adhere to a 2 1 ¯ 1 ¯ 0 / (0 1 1 ¯ 3) coherent twin orientation relationship, which corresponds to a grain geometry that is incommensurate with a perfect crystallographic nature. This coherency is primarily achieved via the small grain having an orientation that rotates internally by 10±2° across its volume, when going between the two interfaces formed with the neighboring large grains. The energy associated with this structural distortion is compensated by the formation of the coherent twin boundaries, such that the triplets are a stable or semi-stable growth form that are abundant in the film. The small (1 0 1 ¯ 3) texture grains may renucleate persistently, taking either of two possible orientations from the underlying tetrahedral coordination. By developing a phenomenological model for the triplet geometry and form, we associate these two orientations to small hexagonal caps and angled wedges seen in the surface morphology of the film. These findings potentially carry relevance for a wide range of vapor deposited compact films and free-standing nanostructures of wurtzite phase octet binary semiconductor compounds. We therefore believe that these insights can stimulate new research, for instance to obtain a more fundamental understanding of the growth mechanisms at the atomistic level. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A model for the kinetics of residual stress evolution is described that can be applied to both the relaxation during a growth interruption and the recovery following resumption of growth. The stress is attributed to simple atomistic processes based on reversible diffusion of atoms in and out of the grain boundary. Each of these processes is considered separately to understand how the rates differ during relaxation and recovery and how they depend on grain size, film thickness, temperature, deposition rate, and initial stress. The model is compared with experimental data obtained by others for several materials (Fe, Ni and Au). Image, graphical abstract [ABSTRACT FROM AUTHOR]

The flexoelectric effect describes the electromechanical coupling of a strain gradient to a polarization and vice versa. This effect scales linearly with permittivity and strain gradients can get very high for dimensions on the micro and nanoscale. Even though the flexoelectric effect can be best exploited within micro or nanoelectromechanical systems (M/NEMS) applications, it has not been established in today's M/NEMS device architectures as other transducer principles, like piezoelectricity. In this work, values of the converse flexoelectric coefficient for one of the most promising flexoelectric materials, titanium dioxide (TiO 2) are provided. The experimental results are based on a carefull characterization of IrO 2 /TiO 2 /IrO 2 cantilevers. Besides CMOS compatiblity TiO 2 is selected as functional thin film material as it offers a very high permittivity and shows no hysteresis or saturation effects as it is neither ferro- nor paraelectric. Additionally, it guarantees a low cost, lead-free realization and can be directly integrated in a standard silicon MEMS fabrication process by sputter deposition. In order to correctly determine the flexoelectric coefficient, other electromechanical coupling effects are considered and assessed. The flexoelectric coefficient is shown to be µ eff = 1.78 ± 0.16 nC m−1 at 10 kHz. The flexoelectric coupling constant with a value of 2.75 V is in good agreement with that theoretically predicted by Kogan's estimate of 3.14 V. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Indium-doped zinc oxide (IZO) polycrystalline thin films were grown on polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and as reference on 7059 Corning glass substrates at room temperature by radio frequency magnetron sputtering from a target prepared with a mixture of ZnO and In2O3 powders. The structural, optical, and electrical properties of the films were analyzed and compared. The IZO polycrystalline films showed n-type conductivity. The electrical resistivity drops significantly, and the carrier concentration increases as a consequence of In incorporation within the ZnO crystalline lattice. In both cases the changes are of several orders of magnitude. The resistivity obtained was 3.1 ± 0.5 x 10-3 Ω-cm for an IZO sample grown on PET with a carrier concentration of 3.1 ± 0.7 x 1020 cm-3, the best mobility obtained was 27.7 ± 0.8 cm2V-1s-1 for an IZO sample grown on PEN. From the results, we conclude that n-type IZO polycrystalline films with high transmittance, high mobility and low resistivity were obtained on flexible transparent substrates.

Graphical abstract Highlights • We extract the cross-plane thermal conductivity of 75 and 246 nm polysilicon films. • The values we report are the lowest ever reported for undoped polysilicon films. • Phonon scattering on defects near grain boundaries reduces thermal conductivity. • A potential improvement in the thermoelectric energy conversion efficiency (ZT). Abstract Silicon thin films with sub-1 µm thickness are of technological significance in many electronic and energy conversion devices. While a number of previous works have investigated the in-plane thermal conductivity of silicon films, less reported is their cross-plane thermal conductivity, particularly at sub-1 µm thickness. Here, we report on the cross-plane thermal conductivity of sub-1 µm, undoped, polycrystalline silicon films (75 and 246 nm) with columnar grain structure at room temperature. Using an optical pump-probe thermoreflectance metrology and a semi-classical phonon transport model, we find the cross-plane thermal conductivity to be 4.5 ± 0.8 and 12.5 ± 2.3 W m−1 K−1 for the 75 and 246 nm films, respectively. To the best of our knowledge, the cross-plane thermal conductivities we report here are the lowest ever reported for undoped polycrystalline silicon films with columnar grain structure, which can be ascribed to the impact of increased phonon scattering by a higher density of defects as compared to previous data. Given that a significant reduction in phonon thermal conductivity is required to enhance the thermoelectric energy conversion efficiency, our findings may be promising particularly for thermoelectric energy conversion applications. [ABSTRACT FROM AUTHOR]

Polycrystalline and single crystal antiferromagnetic D0 19 -Mn 3 Ge thin films were grown by magnetron sputtering on GaN (0001) and Pt (111) templates at different substrate temperatures. Later, a CoFeB layer was grown on top of the D0 19 -Mn 3 Ge films at room temperature. Single crystal D0 19 -Mn 3 Ge thin films, with high surface roughness, induced an increase of the coercivity of the CoFeB ultrathin films, meanwhile polycrystalline D0 19 -Mn 3 Ge thin films, with uniaxial texture and low surface roughness, induced positive exchange bias at room temperature by cooling the sample under a magnetic field of 2 T. No exchange bias was observed with lower cooling magnetic fields. The non-zero magnetic moment of uncompensated D0 19 -Mn 3 Ge grains of the textured films couple antiferromagnetically leading to positive exchange bias. [Display omitted] • D019-Mn3Ge/CoFeB/Ge stacks were grown on GaN (0001) and Pt (111) templates. • High substrate temperature induces the growth of single crystal thin films. • Single crystal layers with high surface roughness induce coercivity enhancement. • Positive exchange bias is observed on polycrystalline samples with low roughness. [ABSTRACT FROM AUTHOR]

Solid phase crystallization (SPC) of amorphous GeSn (a-GeSn) layers with a Sn content of 2% on various insulating substrates of Si 3 N 4 , sapphire, and Y 2 O 3 have been investigated. We found that Si 3 N 4 , which has almost same value of a higher surface energy with sapphire and the value is about twice as high as Y 2 O 3 , could be reduced the SPC temperature of a-GeSn layers (to 400 °C) compared with the other cases. We can see that a maximum grain size as large as 0.9 µm was achieved for polycrystalline GeSn layers on Si 3 N 4 by the annealing at 450 °C for 5 h. Correspondingly, a relatively higher Hall hole mobility (180 cm 2 /Vs) was obtained. [ABSTRACT FROM AUTHOR]

We have synthesized (010) textured polycrystalline thin films of gallium ferrite (GaFeO 3 or GFO) on n-Si(100) and Pt/Si(111) substrates using sol-gel assisted spin coating technique. Structural characterization using x-ray diffraction and Raman spectroscopy confirms formation of single phase with crystallite size ∼37–47 nm. Magnetic characterization demonstrates saturated magnetic hysteresis loop at room temperature and indicates that due to reduced crystallite size, ferri to paramagnetic transition temperature, T C ∼300 K is higher compared to bulk GFO, reported earlier. Room temperature piezo-response force microscopic analysis reveals local ∼180° phase switching of ferroelectric domains at very high coercive field, ∼700 kV/cm, consistent with recent experimental and first-principles studies. Our study opens up the possibility of integrating polycrystalline GFO in novel room temperature multiferroic devices. [ABSTRACT FROM AUTHOR]

Physical vapor deposition (PVD) simulations are performed using a phase-field model to study microstructure evolution in single-phase polycrystalline materials as a function of deposition conditions. Specifically, this work focuses on the influence of (i) polycrystalline substrate microstructure with low-angle and high-angle grain boundaries (GBs), (ii) incident vapor flux rate, and (iii) model parameters controlling grain evolution dynamics. Simulation results show that low-angle and high-angle GBs in the substrate promote the formation of low-angle and high-angle GBs within the deposited thin film, in qualitative agreement with experimental reports. Changing the vapor flux rate has a significant influence on the deposited microstructure. A relatively low flux rate is found to provide a thin film with no subsurface porosity, smoothed surface roughness, and a mixture of grain sizes. With an increased vapor flux rate, uniformly distributed surface columnar features are observed with subsurface porosity. The GBs migrate during growth to align with these surface features. At the largest flux rate studied, a dendritic style microstructure is formed where the GBs tend to align with and grow along the regions of low phase density within the thin film. Finally, a parametric study is performed on the phase-field model grain evolution parameters to elucidate their role on grain boundary thickness, internal grain variations and grain rotation during simulated PVD. [ABSTRACT FROM AUTHOR]

[Display omitted] • A kinetic model explains and predicts residual stress evolution during deposition of sputtered and evaporated metallic thin films. • The model includes stress generation from deposition processes, grain growth and energetic particle bombardment. • The model is used to analyze six metallic thin films (Cu, Ni, Co, Cr, Mo, W) deposited under an array of deposition conditions. Many published studies have quantified film stress evolution for different processing conditions and deposition methods. Here, data from multiple wafer curvature measurements in the literature (for evaporated and sputter-deposited Cu, Ni, Co, Cr, Mo and W) are analyzed in terms of a kinetic model to develop a comprehensive picture of the processes that control film stress. The model includes the effects of film growth kinetics, grain growth and incoming particle energy. Non-linear least squares fitting of the data to this model enables the determination of kinetic parameters that control the stress for each material. The fitting for each material is done in a way that optimizes the parameters simultaneously for all the measurements, both sputtered and evaporated. Parameters that depend only on the material are constrained to have a common value among all the data sets for that material. The validity of the resulting parameters is evaluated by comparing with values estimated from the underlying physical mechanisms. [ABSTRACT FROM AUTHOR]

In the present work, optical, electrical, structural and morphological characterization of polycrystalline thin films of ZnO and Al:ZnO have been reported. Aerosol assisted chemical vapour deposition technique has been adopted for the growth of the films on the glass substrate at 480 °C. Al-fraction in Al:ZnO thin films was determined by using energy dispersive x-ray analysis. In the visible to near-infrared regions, all the films were found to exhibit high average transmittance ≥80%. Blue shift of energy bandgap, from 3.20 to 3.50 eV, has been observed with increasing Al-fraction in the Al:ZnO thin films. For highly doped Al:ZnO thin films, both theoretical and experimentally measured values of carrier concentration (≈ 10 20 cm −3 ) were greater than Mott's critical value (≈ 10 19 cm −3 ) and supports the blue shift of the bandgap. The figures of merit of the films are found to be around 10 −2 Ω −1 suggesting the applicability of Al:ZnO thin films as a transparent electrode. The observed variation of carrier effective mass with increasing Al-doping agrees quantitatively well with the theoretical calculations. At high Al-fraction (≥ 12 at .%), the compressive strain generated in ZnO lattice is due to the presence of amorphous Al 2 O 3 or AlO x at the grain boundaries. X-ray diffraction suggests that the films were single phase and polycrystalline in nature. Atomic force microscopy of Al:ZnO films reveals a systematic change in surface morphology with increasing Al-fraction in the films. The results demonstrate the potentiality of producing thin films of transparent conducting oxides with good electrical, optical, structural and morphological properties via a low-cost deposition technique. [ABSTRACT FROM AUTHOR]

The growth mechanism, microstructure, and crystal structure of the polycrystalline n -Bi 2 Te 3 thin films with thicknesses d = 15–350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi 2 Te 3 . It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d . The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n -Bi 2 Te 3 thin films of a sufficiently high quality. [ABSTRACT FROM AUTHOR]

The effectiveness of different approaches used for improvement of stability of colossal magnetoresistance-B-scalar magnetic field sensors made from polycrystalline manganite La 0.83 Sr 0.17 MnO 3 thin films were considered. We show that the ageing process of sensors can be accelerated by annealing the films in Ar atmosphere at 75–125 °C and covering them by hot melt adhesive (polyethylene). Ageing kinetics of electrical resistance and magnetoresistance ( MR ) were investigated as well as the influence of hot melt adhesive. Despite of increased resistance only small changes of the MR and the temperature coefficient of resistance were observed. The obtained results are explained by the oxygen release, displacement or redistribution which takes place most probably in grain boundaries of polycrystalline manganites. Based on the obtained results optimal conditions for the stabilization of encapsulated sensors parameters were found resulting in the resistance drift less than 1.5% per year. [ABSTRACT FROM AUTHOR]

Microstrain distributions were acquired in functional thin films by high-resolution X-ray microdiffraction measurements, using polycrystalline CuInSe2 thin films as a model system. This technique not only provides spatial resolutions at the submicrometre scale but also allows for analysis of thin films buried within a complete solar-cell stack. The microstrain values within individual CuInSe2 grains were determined to be of the order of 10−4. These values confirmed corresponding microstrain distribution maps obtained on the same CuInSe2 layer by electron backscatter diffraction and Raman microspectroscopy. [ABSTRACT FROM AUTHOR]