Changes In Film Properties Research Articles

Annealing effects on a-SiC:H and a-SiCN:H films deposited by plasma CVD methods

Hydrogenated amorphous silicon carbide (a-SiC:H) and carbonitride (a-SiCN:H) films were deposited in RF and mid-frequency (MF) discharges and electron cyclotron resonance (ECR) plasma. Annealing was performed in high vacuum up to 1000 °C and the temperature-dependent gas effusion from the films was investigated in situ by mass spectrometry. Changes of mechanical film properties, i.e. thickness, stress and Young's modulus, were determined ex situ by profilometry and nanoindentation, respectively. Using elastic recoil detection analysis, Rutherford backscattering and X-ray photoelectron spectroscopy, effects of annealing on elemental composition and chemical bonding were investigated. Annealing the a-SiC:H films significantly increased their Young's modulus and decreased their thickness by up to 25% in the case of ECR plasma deposition. The a-SiCN:H films deposited by MF and RF discharge practically retained their Young's modulus and the film thickness shrinkage was below 3%. At intermediate temperatures, these films showed a small thickness increase. For ECR-deposited a-SiCN:H, the expansion was larger and accompanied by a distinct reduction of Young's modulus. Hydrogen effusion and plastic flow under both compressive and tensile stress have a pronounced impact on the mechanical film properties. Annealing effects on film structure and properties are discussed and fundamental processes are derived.

Solubility considerations in relative block crystallization and morphology of PEO‐ b ‐PCL films

Poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) is a heavily investigated amphiphilic crystalline-crystalline diblock copolymer. Its macroscopic physical properties are influenced by the crystallization behavior, which is robust due to similar crystallization temperatures of PEO and PCL. As such, tailoring the crystallinity and crystalline morphology should be advantageous to achieving desired changes in film properties. One method to manipulate the crystallization, analyzed here, is the selective solvation of one block during solvent casting. By careful solvent selection, the crystallization of PEO and PCL during solvent evaporation led to changes in relative crystallinity and film morphology. The effect of environmental humidity on the crystallization mechanism and relative block crystallization was explored in detail using Fourier-transform infrared spectroscopy.

The vacuum arc ion source for indium and tin ions implantation into phase change memory thin films.

One of the most prospective electrical and optical nonvolatile memory types is the phase change memory based on chalcogenide materials, particularly Ge2Sb2Te5. Introduction of dopants is an effective method for the purposeful change of Ge2Sb2Te5 thin film properties. In this work, we used the ion implantation method for the introduction of In and Sn into Ge2Sb2Te5 thin films by a Multipurpose Test Bench (MTB) at the National Research Center "Kurchatov Institute"-Institute for Theoretical and Experimental Physics. For Sn and In ion implantation into Ge2Sb2Te5, the following MTB elements were used: a vacuum arc ion source, an electrostatic focusing system, and a system for current and beam profile measurements. The MTB parameters for Sn and In ion implantation and its effect on the material properties are presented. Implanted Ge2Sb2Te5 thin films were irradiated by femtosecond laser pulses. It was shown that the ion implantation resulted in a decrease in the threshold laser fluence necessary for crystallization compared to the undoped Ge2Sb2Te5.

(Invited) A Surface Science Toolbox for Understanding Atomic Layer Epitaxy

Atomic Layer Epitaxy (ALEp) is a promising subset of atomic layer processes (ALPs) which has the potential to open a new realm of non-equilibrium semiconductor growth. In ALEp, the objective is to grow crystalline, epitaxial layers on a crystalline substrate for active regions of electronic and optoelectronic devices. This requires expansion of the atomic layer deposition (ALD) processing space to higher temperatures and adds constraints of crystallinity and purity; electronic grade requires impurity concentrations less than ppm. While ALEp has been shown to maintain the self-limiting nature of ALD at temperatures up to 500°C, the additional materials quality criterion requires a more complete understanding of the ALEp process if it is to be fully successful. In this regard, it is essential to develop a set of surface science tools that can be employed either in situ or in vacuo to ensure that atmospheric exposure does not influence or interfere with observed process mechanisms. In this work, we highlight the development and early application of a suite of in situ or in vacuo characterization techniques aimed at providing surface and near-surface structure assessments: low energy electron diffraction (LEED) and grazing incidence small angle x-ray scattering (GISAXS); as well as surface chemistry assessments: (x-ray photoelectron spectroscopy (XPS), resonant ion trap mass spectrometry (RIT-MS) and reflection-absorption infrared spectroscopy (RAIRS). We present select results from these methods during efforts to develop plasma-assisted ALPs for GaN surface preparation for epitaxy and for early plasma-assisted ALEp growth of heteroepitaxial AlN, InN and AlInN films on GaN and Al2O3 substrates. In the former example, in situ GISAXS studies have been used to optimize an emulated gallium flash off (GFO) ALP of as-received GaN substrate surfaces as part of a preparation of such surfaces for epitaxy. A combination of an ex situ UV/O3 oxidation and concentrated HF etch followed by 10 cycles of an emulated GFO ALP result in the smoothest, cleanest surfaces – highly suitable for epitaxy [1,2]. In the latter application, in situ GISAXS studies are used to characterize the nature of the growth mode of AlN and InN binaries and select AlInN ternaries achieved through digital alloying on optimally prepared GaN substrate surfaces. For InN binary growth, which ultimately grows in a 3D mode, the duration of the plasma pulse is shown to influence the growth mode between a bimodal distribution of islands for short pulses to a single mode distribution for intermediate pulses to etching for the longest pulses [3]. Further, we found that the transition from early 2D to ultimate 3D growth and the shape and size of the islands that result are quite sensitive to growth temperature even inside the “ALEp window”[4]. We discovered that although pure InN and AlN grew in 3D and 2D modes, respectively, the InAlN growth mode did not follow a simple trend as the nominal In composition was tuned from InN to AlN. Instead, select compositions (50% and 83% In) showed more 3D growth while others (19% and 64% In) showed 2D growth. Changes in plasma chemistry are also found to affect growth mode and film quality and will be highlighted. These changes in film properties with plasma pulse variations are correlated to independent measurements of plasma properties in an effort to establish plasma process – film property relationships. A combination of RAIRS and RIT-MS will be presented to further illustrate the role of plasma chemistry, while combined in vacuo LEED and XPS will be presented to highlight early film growth evolution. [1] S.G. Rosenberg, D.J. Pennachio, C. Wagenbach, S.D. Johnson, N. Nepal, A.C. Kozen, J.M. Woodward, Z.R. Robinson, H. Joress, K.F. Ludwig, C.J. Palmstrom and C.R. Eddy, Jr., Journal of Vacuum Science & Technology A 37, 020908 (2019). [2] S.G. Rosenberg, C. Wagenbach, V.R. Anderson, S.D. Johnson, N. Nepal, A.C. Kozen, J.M. Woodward, Z.R. Robinson, M. Munger, H. Joress, K.F. Ludwig and C.R. Eddy, Jr., Journal of Vacuum Science & Technology A 37, 020928 (2019). [3] N. Nepal, V. Anderson, S. D. Johnson, B. P. Downey, D. J. Meyer, Z. Robinson, J. M. Woodward, K. F. Ludwig, C. R. Eddy, Jr., Journal of Vacuum Science and Technology A 37, 020910 (2019). [4] J.M. Woodward, S.G. Rosenberg, A.C. Kozen, N. Nepal, S.D. Johnson, C. Wagenbach, Z.R. Robinson, K.F. Ludwig, Jr. and C.R. Eddy, Jr., Journal of Vacuum Science & Technology A 37, 030901 (2019). Figure 1

Processing, structure and properties of reactively sputtered films of titanium dioxide and suboxides

A series of TiOx(0 < x ≤ 2) thin films with different O/Ti ratio were deposited on Si substrates by reactive magnetron sputtering of Ti metal in Ar + O2 plasma. The influence of oxygen flow rate and substrate temperature on the structural, mechanical, and electrical properties of the films was explored. With increasing the oxygen flow rate, the following phases appeared in the following order: Ti metal, Ti(O) solid solution, TiO, Ti2O3, Magnéli phases, rutile and anatase TiO2. With increasing the temperature, the crystallinity, and oxygen content of the films varied, which resulted in changes in film properties. The trend of hardness and electrical conductivity in ceramic TiOx films is TiO > Ti2O3 > Magneli phases > rutile phase.

Multivariate multiple regression models of poly(ethylene-terephthalate) film degradation under outdoor and multi-stressor accelerated weathering exposures.

Developing materials for use in photovoltaic (PV) systems requires knowledge of their performance over the warranted lifetime of the PV system. Poly(ethylene-terephthalate) (PET) is a critical component of PV module backsheets due to its dielectric properties and low cost. However, PET is susceptible to environmental stressors and degrades over time. Changes in the physical properties of nine PET grades were modeled after outdoor and accelerated weathering exposures to characterize the degradation process of PET and assess the influence of stabilizing additives and weathering factors. Multivariate multiple regression (MMR) models were developed to quantify changes in color, gloss, and haze of the materials. Natural splines were used to capture the non-linear relationship between predictors and responses. Model performance was evaluated via adjusted-R2 and root mean squared error values from leave-one-out cross validation analysis. All models described over 85% of the variation in the data with low relative error. Model coefficients were used to assess the influence of weathering stressors and material additives on the property changes of films. Photodose was found to be the primary degradation stressor and moisture was found to increase the degradation rate of PET. Direct moisture contact was found to impose more stress on the material than airbone moisture (humidity). Increasing the concentration of TiO2 was found to generally decrease the degradation rate of PET and mitigate hydrolytic degradation. MMR models were compared to physics-based models and agreement was found between the two modeling approaches. Cross-correlation of accelerated exposures to outdoor exposures was achieved via determination of cross-correlation scale factors. Cross-correlation revealed that direct moisture contact is a key factor for reliable accelerated weathering testing and provided a quantitative method to determine when accelerated exposure results can be made more aggressive to better approximate outdoor exposure conditions.

Spectroscopic ellipsometry characterization of multilayer optical coatings

The performance of an optical coating stack depends on thickness and refractive index of each layer. In situ spectroscopic ellipsometry (SE) can track coating properties in real-time, but ex situ SE characterization is limited by the large number of unknown sample properties. We review various SE characterization strategies for multilayer structures using 37-layer alternating high-low index stacks of Ta2O5 and SiO2. A “tooling factor” for each coating material is developed to inform how the actual layer thicknesses compare to nominal specifications.We also introduce tests for sources of error that can occur during multilayer processing. Process drift may produce a gradual change in film properties, such as a slight increase or decrease in coating thickness or optical constants. This is modeled by adding a gradient to each tooling factor. User-error is also considered, where incorrect parameter entry produces an unintentional stack design. An erroneous layer is identified by systematically testing each layer. A “blind” test was performed to determine SE sensitivity to such errors, where a single layer was intentionally altered within a 37-layer stack, and systematic testing was able to resolve the altered layer thickness and position in the stack.

Biodegradation of Poly(3-Hydroxybutyrate) and Poly(3-Hydroxybutyrate-Co-3-Hydroxy-4-Methylvalerate) Films by Porcine Pancreatic Lipase

In the current work, the degradation of poly (3-hydroxybutyrate) (PHB) and poly (3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate) (PHB4MV) films was studied in vitro by pancreatic lipase. The changes in film properties were traced by several analytical methods: the change of weight, molecular weight, and Young’s modulus (by nanoindentation) were measured. During the six months of polymer films degradation the weight of samples decreased slightly, while a great increase in Young's modulus due to the relatively fast degradation of the amorphous areas was observed, as well as molecular weight of polymers decreased significantly. Weight loss of PHB4MV is faster than degradation rate of PHB, but the molecular weight of PHB 1700 decrease rapidly than PHB4MV; the Young’s modulus of polymers remained relatively unchanged.

Process parameter analysis and parasitic reaction of ZnO grown through MOCVD

The technological parameters of metalorganic chemical vapor deposition (MOCVD) greatly influence the quality and properties of films. According to the chemical reaction mechanism of a ZnO film grown by using DEZn and H2O and the stable flow state in the reaction cavity, the effects of the process parameters of ZnO-MOCVD, including cavity pressure, substrate speed, and growth temperature, on the film's properties and parasitic reaction depend on the reaction mechanism and stable flow state in the reaction cavity. In this paper, the reasons for the change of film properties caused by the process parameters are also discussed. This study shows that increasing the pressure of the cavity is beneficial to the improvement of the film quality and does not affect the parasitic reaction. The improvement of the rotating speed is beneficial to the improvement of the film quality. However, the parasitic reaction increases slightly with the increase in speed or growth temperature. In addition, the increase in the growth temperature is beneficial to the increase of the film thickness, but is detrimental to the film uniformity. This study provides theoretical guidance for analyzing the regularity of ZnO films grown through DEZn and H2O in MOCVD.

Revisitation of the structure zone model based on the investigation of the structure and properties of Ti, Zr, and Hf thin films deposited at 70–600 °C using DC magnetron sputtering

The group 4 metals Ti, Zr, and Hf, which have similar chemical behaviors, were sputter-deposited on glass substrates at substrate temperatures of 70, 200, 300, 400, 500, and 600 °C by direct current magnetron sputtering using Ar as discharge gas. On the basis of the obtained cross-sectional and surface morphologies, crystallographic structures, and film properties, the structure zone model for sputter-deposited metal thin films was revisited and discussed. The x-ray diffraction measurements show that all Ti, Zr, and Hf thin films have a hexagonal close-packed structure with ⟨101⟩ or ⟨001⟩ preferred orientations. Scanning electron microcopy observations show tableland-like flat surfaces with dense, wide, columnar cross sections for Ti thin films and fine dome-shaped surfaces with fine columnar cross sections to tableland-like flat surfaces with wider columnar cross sections for Zr and Hf thin films. Atomic force microscopy also reveals changes from fine dome-shaped to flat surface morphologies. The quantitative data on the lattice strain, crystallite size, surface roughness, and electrical resistivity reduced to that of the bulk material were plotted both against the unnormalized and normalized substrate temperatures. The latter data plots show a smaller dispersion than the former ones. The lattice strain and reduced resistivity of all Ti, Zr, and Hf thin films display a sharp bend at a normalized temperature of ∼0.30–0.35. The film surface, cross-sectional morphologies, and film property changes display a clear transition from zones 1 to 2 through zone T. The data obtained in this paper are utilized to systematically explain the effectiveness and appropriateness of the use of the normalized substrate temperature to categorize the film structure, morphologies, and properties of thin films.The group 4 metals Ti, Zr, and Hf, which have similar chemical behaviors, were sputter-deposited on glass substrates at substrate temperatures of 70, 200, 300, 400, 500, and 600 °C by direct current magnetron sputtering using Ar as discharge gas. On the basis of the obtained cross-sectional and surface morphologies, crystallographic structures, and film properties, the structure zone model for sputter-deposited metal thin films was revisited and discussed. The x-ray diffraction measurements show that all Ti, Zr, and Hf thin films have a hexagonal close-packed structure with ⟨101⟩ or ⟨001⟩ preferred orientations. Scanning electron microcopy observations show tableland-like flat surfaces with dense, wide, columnar cross sections for Ti thin films and fine dome-shaped surfaces with fine columnar cross sections to tableland-like flat surfaces with wider columnar cross sections for Zr and Hf thin films. Atomic force microscopy also reveals changes from fine dome-shaped to flat surface morphologies. The quantit...

Understanding near infrared absorption in tin doped indium oxide thin films

Tin doped indium oxide (In2O3:Sn (ITO)) thin films RF sputtered under similar conditions on soda lime glass and single crystal silicon wafers (c-Si) are used to study near infrared optical absorption variations during film growth. The presence of strong free carrier absorption and phonon absorption in the low photon energy spectral range provides an opportunity to disentangle tailing effects extending in the near infrared to visible spectral range. Toward that end, a model describing ITO film optical properties in the form of the complex dielectric function (ε = ε1 + iε2) from ex situ ellipsometry collected over 0.4 to 4.1 meV, 0.035 to 0.4 eV, and 0.75 to 5.89 eV spectral range is developed to describe these features along with other higher energy electronic transitions. In situ real time spectroscopic ellipsometry (RTSE) from 0.75 to 5.89 eV is used to track changes film structure and optical response during thin film growth. Optical emission spectroscopy indicates the plasma is very stable during deposition implying that film property changes with thickness are not correlated with changes in plasma chemistry. Film resistivity (ρ), mobility (µ), scattering time (τ), and carrier concentration (n) are determined from the free carrier absorption component of ε. Increased near infrared absorption manifested in ε obtained from RTSE data analysis is hypothesized to originate from enhancement of OH-group phonon absorption due to the presence of water molecules in the chamber at the beginning of growth.

A Review on Preparation and Properties of Cellulose Nanocrystal-Incorporated Natural Biopolymer

The emergence of green clean technology has escalated the use of eco-friendly biopolymer by substituting petroleum-derived polymers. Over the years, natural biopolymers’ properties have been evaluated to check their applicability in food packaging industries. However, most of the biopolymers show poor barrier and mechanical properties compared to petroleum-derived polymers. Recently, cellulose nanocrystal has acquired attention of the researchers as potential prospective filler, which can overcome the drawbacks of biopolymer films. The basic advantages of cellulose nanocrystal are its high strength and stiffness, high surface area, biodegradability, etc. Therefore, lignocellulosic biomass, animal, and bacterial cellulose have been used as feedstock of cellulose nanocrystal, and then incorporated into the biopolymer films. This review provides detailed procedure of cellulose nanocrystal extraction in a stepwise manner and discusses the changes in film properties after reinforcement into different biopolymers.

Pentablock copolymer morphology dependent transport and its impact upon film swelling, proton conductivity, hydrogen fuel cell operation, vanadium flow battery function, and electroactive actuator performance

Ionomer composition and morphology impacts functional group distribution, water and ion-transport, and physical properties related to toughness, and degradation resistance. NEXAR MD9100 a pentablock copolymer (PBC) film morphology was dramatically altered when solution-cast into a film using tetrahydrofuran (THF) versus a cyclohexane: heptane (C:H) mixture. Film property and morphology changes were evaluated using Transmission Electron Microscopy (TEM), Small-Angle X-ray Scattering (SAXS), and electrochemical impedance spectroscopy. These changes were compared to Nafion 117 and Nafion 212. Average sulfonated inter-domain spacing through the film's thickness increased from 22.3nm (C:H cast) to 30.5nm (THF cast) that was estimated using SAXS. TEM revealed that PBC solution-cast films from C:H contained a random distribution of discrete sulfonated domains. An ordered PBC morphology consisting of lamella and hexagonally packed ion groups were created from a THF solution-cast film. These changes were attributed to favorable solvent-ionomer interactions during solvent evaporation and film densification. This ordered morphology led to increased conductivity (4.5mS/cm versus 47.8mS/cm), improved fuel cell power (19mW/cm2 versus 160mW/cm2), enhanced ionomer actuation (3.0cm versus 6.9cm), and modest self-discharge improvements for a vanadium redox-flow battery. This study demonstrates that morphology impacts ionomer physical properties, transport, and device function.

Tensile, barrier, dynamic mechanical, and biodegradation properties of cassava/sugar palm fiber reinforced cassava starch hybrid composites

The hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) by casting technique using cassava starch (CS) as a matrix and fructose as a plasticizer. The chemical composition and physical properties of SPF and CB were studied in this work. SPF was added at different loadings of 2, 4, 6, and 8% dry starch to the CS/CB composite films with 6% CB. The addition of SPF influenced the hybrid properties. It was observed that the addition of 6% SPF to the composite film increased the tensile strength and modulus up to 20.7 and 1114.6 MPa, respectively. Also, dynamic-mechanical properties of the hybrid composites were investigated using a DMA test. The incorporation of SPF increased the storage modulus (E’) value from 0.457 GPa of CS to 1.490 GPa of CS-CB/SPF8 hybrid composite film. Moreover, the incorporation of SPF slightly decreased the water vapor permeability (WVP) compared to the CS/CB composites film. It can be concluded that the incorporation of SPF led to changes in cassava starch composite film properties, potentially improving the bio-degradability, WVP, and mechanical properties of the film. Based on its excellent properties, CB/SPF-CS hybrid composite films are suitable for various purposes such as packaging, automotive, and agro-industrial applications, at lower cost.

Soft X-ray irradiation effect on the fluorinated DLC film

The irradiation effect on fluorinated diamond-like carbon (F-DLC) film was investigated by measuring the dose dependence of various film properties using synchrotron radiation (SR) in the soft X-rays in the SR dose region from 0 to 2000mAh. Film flatness was maintained but various film properties and surface properties were found to be changed by the SR irradiation. Wettability of the F-DLC film surface increased dramatically within 20mAh SR exposure, which was ascribed to the decrease in fluorine on the film surface. Film thickness, film density, composition ratio of fluorine atom in film decreased and sp2/(sp2+sp3) ratio of carbon atoms increased within 300mAh SR exposure, which were ascribed to the desorption of species containing fluorine atoms. In addition, dominant desorbed species emitted from F-DLC film were found in the fluorocarbon group, CFx. Changes in film properties and film thickness did not proceed, when fluorine content in the F-DLC film decreased to about 10% after the 300mAh SR exposure.

폴리테트라메틸렌 에테르 글리콜과 폴리카보네이트 디올로부터 합성한 수분산 폴리우레탄 필름의 가수분해에 의한 특성 변화

폴리테트라메틸렌 에테르 글리콜과 폴리카보네이트 디올로부터 합성한 수분산 폴리우레탄 필름의 가수분해에 의한 특성 변화

Cassava/sugar palm fiber reinforced cassava starch hybrid composites: Physical, thermal and structural properties

A hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) using casting technique with cassava starch (CS) as matrix and fructose as a plasticizer. Different loadings of SPF (2, 4, 6 and 8% w/w of dry starch) were added to the CS/CB composite film containing 6% CB. The addition of SPF significantly influenced the physical properties. It increased the thickness while decreasing the density, water content, water solubility and water absorption. However, no significant effect was noticed on the thermal properties of the hybrid composite film. The incorporation of SPF increased the relative crystallinity up to 47%, compared to 32% of the CS film. SEM micrographs indicated that the filler was incorporated in the matrix. The film with a higher concentration of SPF (CS-CB/SPF8) showed a more heterogeneous surface. It could be concluded that the incorporation of SPF led to changes in cassava starch film properties, potentially affecting the film performances.

Effect of Glycerol on the Properties of Tapioca Starch Film

Biodegradable films from tapioca starch (TPS) were formed by tape casting. The impact of glycerol (0, 5, 10, 15 and 20%) on the mechanical properties was investigated. The increase in glycerol content reduces the tensile strength while increasing the elongation at break. The varying concentrations of glycerol led to changes in tapioca starch edible film properties, potentially affecting film performances. The merging and increase in the intensity of absorption between 3700-3300 cm-1 as a result of increase in glycerol proportion is due to possible interaction of the OH groups in TPS and glycerol thereby increasing intermolecular H-bond.

Tailoring of microstructure and optoelectronic properties of Aluminum doped Zinc Oxide changing gun tilt

The influence of gun tilt on microstructure and optoelectronic properties of ZnO:Al thin films deposited by magnetron sputtering onto transparent glass substrates was studied. The structural and morphological film properties were investigated according to the cathode angle that placed in confocal geometry configuration inside sputtering system. X-ray diffraction (XRD) and Atomic Force Microscope (AFM) were used, respectively. Film microstructure was analyzed by high resolution transmission electron microscopy (HR-TEM). Results showed relevant changes in AZO film properties depending on gun tilt, fact that can affect the device performance. Rougher AZO surfaces with lower average transparency values in visible range and worse electrical properties were observed when gun tilt decreased. These strong dependences can be considered as important aspects when design suitable electrodes for optoelectronic devices. In this sense, the ability of tuning AZO film properties as function of geometrical deposition system configuration was evaluated. This approach would allow fabricating coatings based on the same raw material but different optoelectronic properties.

The Changes in Surface Morphology and Mechanical Properties of Poly(3-Hydroxybutyrate) and its Copolymer Films during &lt;i&gt;In Vitro&lt;/i&gt; Degradation

In the current work, we studied the degradation of PHB films in vitro by pancreatic lipase and in phosphate buffer saline (PBS). We traced the changes in film properties by several analytical methods: the change of weight, surface roughness and morphology (by atomic-force microscopy) and Young’s modulus (by nanoindentation) were measured.PHB is a semicrystalline polymer and thus the films have lamellar structure. During biodegradation, three types of changes were observed on the film surface: appearance of new lamellae, disappearance of lamellae and disintegration of lamellae into shorter fragments. During the six months of polymer films degradation the weight of samples decreased; and an increase in Young's modulus due to the relatively fast degradation of the amorphous areas was observed by nanoindentation.