Search

Thin film growth through nonclassical crystallization with charged nanoparticles as building blocks has been studied in chemical vapor deposition and physical vapor deposition. A similar mechanism ...

Effects of sputtering power, working pressure, and bias on the growth rate, crystallinity, and resistivity of Ag thin films deposited by direct current (DC) magnetron sputtering were investigated. Thin films were deposited on the substrate under the electric biases of − 300, 0, and + 300 V for 30 min with sputtering powers of 20, 50, 100, and 200 W and working pressures of 2.5, 5, 10, and 20 mTorr. Under all sputtering powers, the growth rate of the thin film was increased by the positive bias, whereas it was decreased by the negative bias. For example, the film thicknesses were 345.7, 377.9, and 416.0 nm at − 300, 0, and + 300 V, respectively, at a sputtering power of 100 W and a working pressure of 2.5 mTorr. The bias effect was enhanced as the working pressure decreased. Considering the change of the film growth rate according to the bias, the amount of negatively charged flux was estimated to be roughly 10%. As the working pressure decreased, the crystallinity of the deposited films increased by the positive bias whereas it decreased by the negative bias, which is indicated by the full width at half maximum (FWHM) determined by X-ray diffraction of the Ag (111) peak. The film resistivity had the same tendency. This change in the deposition behavior of the Ag film can be understood as the effect of the charged flux.

Although non-classical crystallization is a relatively revolutionary concept, where a building block for crystallization is neither an atom nor an ion but a nanoparticle, it has become so much established now that numerous papers as well as several books were published and its tutorial and technical sessions were included in international conferences. The purpose of this paper is to review how non-classical crystallization was developed in solution and in the gas phase synthesis of films by chemical vapor deposition (CVD). Findings made in the study of non-classical crystallization in solution turn out to be very useful in understanding of non-classical crystallization of thin films by CVD. Similarly, findings made in the study of non-classical crystallization of thin films by CVD would be useful in understanding of non-classical crystallization of bulk crystals in solution. Therefore, it is synergistic to review non-classical crystallization both in solution and in the gas phase. For example, the presence of charge in nanoparticles is hardly mentioned in non-classical crystallization in solution whereas it is clearly revealed by the current measurement in the gas phase synthesis of thin films by CVD. The building block in non-classical crystallization is not simply a nanoparticle but a charged nanoparticle (CNP). Many evidences indicate that charged nanoparticles (CNPs) should be liquid-like or superplastic and this property changes abruptly with their charging state and size.

Here, using ab initio calculations, we investigated the interaction between transition metals (M) and diamond C(111) surfaces. As a physical parameter describing the catalytic effect of a transition metal on diamond growth, we considered interfacial energy difference, ΔEint, between 1 × 1 and 2 × 1 models of M/C(111). The results showed that the transition-metal elements in the middle of the periodic table (groups 4–10) favor a 1 × 1 M/C(111) structure with diamond bulk-like interfaces, while the elements at the sides of the periodic table (groups 3, 11, and 12) favor a 2 × 1 M/C(111) structure with the 2 × 1 Pandey chain structure of C(111) underneath M. In addition, calculations of MC carbide formation for early transition metals (groups 3–6) showed that they have a tendency to form MC rather than M/C(111), which explains their low efficiency as catalysts for diamond growth. Further analysis suggests that ΔEint could serve as another parameter (catalytic descriptor) for describing catalytic diamond growth in addition to the conventional parameter of the melting temperature of M.

This study examines the insulation coating technology of Fe–Si–Cr powder via selective oxidation annealing, which oxidizes elements selectively by controlling the oxidation potential. The study calculated the oxidation driving force of Fe, Si, and Cr, and conducted a thermodynamic analysis of oxidation and reduction conditions according to temperature and oxidation potential. Based on the results, a selective oxidation annealing was performed in an atmosphere in which Fe is reduced and only Si and Cr are selectively oxidized. The oxidation potential was controlled through the partial pressure ratio of hydrogen and water vapor. The XPS analysis results confirmed that a Si and Cr complex oxide layer formed on the powder surface after the selective oxidation annealing. Afterward, withstanding voltages were analyzed to evaluate the insulation property. Then, the withstanding voltage of the powder applying the selective oxidation annealing increased significantly compared to that of the initial powder. Further analysis showed that the powder annealed in an air atmosphere had a significantly lower saturation magnetic flux density than the initial powder, while the powder applying the selective oxidation annealing had only a slightly reduced saturation magnetic flux density.

By using ab-initio calculations, the adsorption and diffusion properties of charged Au dimers ( Au 2 + and Au 2 − ) on MgO(100) were investigated and compared with those of the charge-neutral dimer ( Au 2 0 ). The most favored adsorption structure of Au 2 + on MgO(100) is the upright dimer on a surface O atom in agreement with that of Au 2 0 . The surface diffusion of Au 2 + on MgO(100) occurs by the leapfrog process with a barrier height of 0.38 eV lower than that of Au 2 0 (0.66 eV). The most stable adsorption structure of Au 2 − on MgO(100) is the flat-lying dimer on two surface Mg atoms. The surface diffusion of Au 2 − on MgO(100) can proceed by the hopping and walking processes with a barrier height in the range of 0.05–0.11 eV, which is much lower than the diffusion barriers of Au 2 + and Au 2 0 . Furthermore, detailed information on the electronic properties of Au 2 0 , Au 2 + , and Au 2 − are also presented.

Abstract Effects of sputtering power on the deposition rate and microstructure, crystallinity, and electrical properties of Ag films during direct current (DC) magnetron sputtering are investigated. Thin films (~ 100 nm) are deposited at sputtering powers of 10, 20, 50, 100, 200 and 300 W and analyzed by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and a four-point probe. The film deposited at a sputtering power of 10 W has the lowest growth rate, but the highest crystalline quality, with the lowest full width at half maximum (FWHM) and the lowest resistivity. The film deposited at a sputtering power of 200 W has the highest growth rate, and the second best crystalline quality in view of FWHM and resistivity. The film deposited at a sputtering power of 50 W has the moderate growth rate, and the worst crystalline quality in view of FWHM and resistivity. High-resolution TEM observations reveal that films deposited at sputtering powers of 10 and 200 W have far fewer defects, such as grain boundaries, dislocations and stacking faults than those deposited at a sputtering power of 50 W. Such deposition behavior could be explained by sputtering power, which affected the generation of the charged nanoparticles. And the high quality of films could be obtained at a high deposition rate, in which charge plays an important role. Graphic Abstract

The phonon densities of states (ph-DOSs) of clean and Ni-terminated C(111) surfaces with 1 × 1 and 2 × 1 surface structures were investigated using ab-initio density functional perturbation theory. The ph-DOSs showed vibrational spectra associated with the surface structures of C(111) and Ni/C(111). Further analyses of various surface phonon modes were performed to identify vibrational features involving the surface atoms of C(111) and Ni/C(111). These features provide important information for experimentally verifying the formation of a diamond bulk-like structure at Ni/C(111), as suggested in a previous study.

Penetrating morphologies at the growth front of abnormally-growing Goss grains in Fe–3%Si steel was examined in view of the possibility that they are the two-dimensional section of the solid-state wetting (SSW) along the triple junction line. To obtain the statistically meaningful data, 102 penetrated grain and 204 penetrating abnormally-growing Goss grain morphologies were examined. The misorientation angles of penetrating and penetrated grains were measured by electron backscattered diffraction. Among the 102 examined penetrated grain boundaries, none has low misorientation angles less than 15°, whereas 17.2% of the 204 penetrating grain boundaries have low misorientation angles, and 23.5% of them have coincidence site lattice boundaries. Besides, boundary energies of penetrating Goss grains, which were estimated from misorientation angles of the three grains in the penetrating morphology, satisfied the energetic condition for SSW along the triple junction line. These results imply that the abnormal grain growth of Goss grains in Fe–3%Si steel occurs by the mechanism of sub-boundary enhanced SSW.

Charged nanoparticles have been shown to be spontaneously generated in the gas phase in various chemical vapor deposition (CVD). Furthermore, it has been shown that these charged nanoparticles can contribute to the growth of thin films, nanowires, nanotetrapods and so on. Here, the generation of charged silicon carbide (SiC) nanoparticles in the gas phase during a hot wire CVD process was studied by capturing nanoparticles with a different delay time on a silicon monoxide membrane of the copper mesh grid for transmission electron microscope. The average size of SiC nanoparticles captured for 30 s increased from 2.9 to 6.1 nm with increasing delay time from 0 to 60 min. The deposition behavior of SiC films was affected by the applied bias on a substrate holder. A homo-epitaxial SiC film as thick as ~ 200 nm was grown under the substrate bias of − 200 V, whereas polycrystalline SiC films were grown under 0 V and + 15 V. It indicates that nanoparticles generated in the gas phase should be charged.

Evolution of abnormally growing Goss grains in Fe–3%Si steel was observed time sequentially by electron backscattering diffraction (EBSD). For example, some specimens were heated at 1080 °C for 5 min, then cooled, polished and observed by EBSD, whose procedure was repeated for 6 times. After each heat treatment at 1080 °C, the abnormal grain growth morphology of Goss grains in Fe–3%Si steel could be observed by polishing away a thin layer of the oxidized surface. Goss grains grew abnormally in a highly irregular way. As a result, some matrix grains were isolated at the growth front, which produced island grains. The irregular growth often resulted in incomplete isolation, which produced peninsular grains. Numerous matrix grains were isolated by the impingement of abnormally growing Goss grains. Once matrix grains became isolated, island or peninsular grains, they shrank much faster than before. If the grain boundary mobility of island and peninsular grains is not low enough, they would shrink in an accelerated way because their local curvature of grain boundary becomes larger as they shrink. Therefore, the high shrinking rate of island and peninsular grains indicates that island and peninsular grains are formed not because of their low grain boundary mobility but because of solid-state wetting.

Increasing the growth rate of thin films and enhancing the film quality have been an issue in the semiconductor manufacturing process. To improve those properties, conventionally the deposition temperature in reactor was increased or a catalyst was added to decompose precursors at low temperature. Here, a new technology utilizing a bipolar carbon fiber ionizer (CFI) was used to achieve a high growth rate and quality of silicon films. The deposition behavior of atmospheric pressure chemical vapor deposition silicon films deposited with and without the bipolar CFI system was compared. The growth rate of silicon films deposited at 450 °C, 500 °C, 700 °C, 900 °C and 1100 °C with the bipolar CFI system was 3.4, 5.6, 3.2, 3.3 and 1.3 times higher than deposited silicon film without the bipolar CFI system. The bipolar CFI system could also improve the crystallinity of the silicon film deposited at 900 °C.

The stable Y5O4F7 suspension for dense yttrium oxyfluoride (YOF) coating by suspension plasma spraying (SPS) was developed. Electrostatically and electrosterically stabilized aqueous Y5O4F7 suspensions were prepared and compared with a commercially available Y5O4F7 suspension without dispersant. The wettability and dispersibility of the Y5O4F7 suspensions were evaluated in terms of the zeta potential, average particle size, and size distribution with electrophoretic light scattering (ELS) and dynamic light scattering (DLS). The viscosity was measured and the sedimentation was tested to examine the fluidity and stability of the Y5O4F7 suspensions. When electrostatic (BYK-154) and electrosteric (BYK-199) dispersants were added to the Y5O4F7 suspension, the isoelectric point (IEP) of Y5O4F7 particles in the suspension shifted to lower pH. The zeta potential of both of electrostatically and electrosterically stabilized Y5O4F7 suspensions were higher than ±40 mV at pH of 8.6, respectively, which were much higher than of the Y5O4F7 suspension without dispersant. Meanwhile, the average particle size of the electrosterically stabilized Y5O4F7 suspension was much smaller than that of the electrostatically stabilized one. The electrosteric stabilization had a great effect on improving the wettability and dispersibility of the Y5O4F7 suspension. The coating rate of the electrosterically stabilized Y5O4F7 suspension was the highest among the three tested suspensions. In addition, the YOF coating deposited with the electrosterically stabilized Y5O4F7 suspension had the highest hardness and the lowest porosity.

When metal thin films deposited typically by sputtering is heated to sufficiently high temperature, thin films tend to disintegrate into individual isolated spherical particles, whose phenomenon is called thermal dewetting. If such metal films are exposed to plasma, however, the dewetting kinetics is enhanced dramatically. One possibility for enhanced dewetting kinetics is the ion bombardment on the film surface from plasma. The other possibility is the excess charge buildup on the film surface provided from plasma. If enhanced dewetting kinetics is due to charge buildup, it can provide an evidence for charge-enhanced kinetics, which has been suggested as a hypothesis to explain the evolution of void-free dense films in non-classical crystallization where the building block is charged nanoparticles. To clarify which is responsible for plasma enhanced dewetting, the dewetting behavior of 100 nm thick Sn films on silicon substrates with native oxide surface was compared between floating and grounded films in the inductively-coupled plasma environment. The dewetting kinetics on the floating film was much higher than that on the grounded film. These results indicate that the charge buildup is responsible for the plasma enhanced dewetting kinetics.

The possibility of preparing highly (002) oriented Ti films on the Si (100) substrate was studied using RF sputtering. The deposition behavior was compared between floating and grounded substrates at room temperature. Highly (002) oriented Ti films could be successfully prepared on the floating Si (100) substrate, which was revealed by X-ray diffraction and high resolution transmission electron microscope. To understand the different deposition behavior between floating and grounded substrates, the incident energy of ions during RF sputtering was estimated from the substrate temperature measured by the K-type thermocouple. The incident energy on the floating substrate was lower by 20% than that on the grounded substrate. It was suggested that the lower incident energy on the floating substrate would be responsible for the deposition of highly (002) oriented Ti films at room temperature.

In the present study, the tensile deformation behavior of transformation-induced plasticity (TRIP)-aided steel under pulsed electric current is investigated. When a pulsed electric current is applied to the specimen during entire tensile deformation, a significant reduction of elongation is observed. The reason is that the mechanically induced martensitic transformation (MIMT) effect does not work properly as the stability of retained austenite phase increases due to temperature rise by the applied electric current. To improve the ductility of the TRIP-aided steel, the pulsing pattern of electric current is modified to apply the electric current only in the early stage of deformation immediately before the phase transformation of retained austenite phase begins to take place. As a result, the elongation is significantly increased by delaying the MIMT effect and making it work properly in the latter stage of deformation. Also, the electrically-induced annealing effect, which occurs in the early stage of deformation where a dislocation plasticity occurs dominantly, contributes to the improvement of elongation. The modified pulsing pattern suggested in the present study provides an easy-to-implement technique to improve the formability of the TRIP-aided steel.

SiOxNy barrier films were deposited at low temperature of ~ 23 °C using inductively coupled plasma chemical vapor deposition (ICP-CVD). When radio frequency power increased at constant ratios of Ar/SiH4 and O2/(O2 + N2), respectively, of 4.5 and 0.1, the aggregation tendency of nanoparticles slightly decreased, whereas when the ratio of Ar/SiH4 was changed from 4.5 to 41, almost spherical nanoparticles, each of which was isolated without aggregation, were observed. Such a near spherical nanoparticle without aggregation produced highly dense films with enhanced barrier property. However, heavily aggregated nanoparticles produced very porous films with deteriorated barrier property. In other words, the film density and barrier property depended significantly on whether nanoparticles were isolated or aggregated. To investigate the formation mechanism of dense SiOxNy barrier film, a transmission electron microscope grid membrane was exposed for 5 s to capture nanoparticles generated in the gas phase using a shutter above the grid membrane during ICP-CVD and the grid membrane was observed by scanning transmission electron microscope. The formation mechanism of the barrier film could be best explained by non-classical crystallization of CVD films, where nanoparticles formed in the gas phase contribute to the film formation.

Non-classical crystallization, in which charged nanoparticles (NPs) are the building blocks of film growth, has been extensively studied in chemical vapor deposition (CVD). Recently, a similar mechanism of film growth has been reported during radio frequency (RF) sputtering with a Ti target and DC magnetron sputtering using an Ag target. In this study, the effect of pressure on the generation of Ti NPs and on the film deposition was studied during RF sputtering with a Ti target. Ti NPs were captured on transmission electron microscopy (TEM) membranes with the electric biases of &minus, 30, 0, and +50 V under 20 and 80 mTorr. The number densities of the Ti NPs were 134, 103, and 21 per 100 &times, 100 nm2, respectively, with the biases of &minus, 30, 0, and +50 V under 20 mTorr and were 196, 98, and 0 per 100 &times, 30, 0, and +50 V under 80 mTorr, which was analyzed by TEM. The growth rate of Ti films deposited on Si substrates was insensitive to the substrate bias under 20 mTorr but was sensitive under 80 mTorr, with the thicknesses of 132, 133, 97, and 29 nm, respectively, after being deposited for 15 min with the substrate biases of &minus, 30, &minus, 10, 0, and +50 V. This sensitive dependence of the film growth rate on the substrate bias under 80 mTorr is in agreement with the sensitive dependence of the number density of Ti NPs on the substrate bias under 80 mTorr.

Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 &deg, C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH4 &ndash, 99% H2 to 3% CH4 &ndash, 97% H2 at 1900 &deg, C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. At 3% CH4 &ndash, 97% H2, the graphite was coated on the hot filament both at 1900 &deg, C and 2100 &deg, C. The graphite coating on the filament decreased the number of electrons emitted from the hot filament. The electron emission at 3% CH4 &ndash, 97% H2 was 13 times less than that at 1% CH4 &ndash, 99% H2 at the filament temperature of 1900 &deg, C. The lower number of electrons at 3% CH4 &ndash, 97% H2 was attributed to the formation of the non-diamond phase, which etched faster than diamond, resulting in a lower growth rate.

Diamond nanoparticles have been synthesized using various methods. Nanodiamonds generated in the gas phase were captured on the membrane of a transmission electron microscope grid during a hot filament chemical vapor deposition (HFCVD) diamond process. In total, ~600 nanoparticles, which were captured for 10 s in six conditions of the capture temperatures of 900 &deg, C, 600 &deg, C and 300 &deg, C and the gas mixtures of 1% CH4-99% H2 and 3% CH4-97% H2, were analyzed for phase identification using high-resolution transmission electron microscopy and fast Fourier transformation. Hexagonal diamond, i-carbon, n-diamond, and cubic diamond were identified. The observation of two or more carbon allotropes captured on the same membrane suggested their coexistence in the gas phase during HFCVD. The crystal structure of carbon allotropes was related to the size of the nanodiamond. The crystal structure of the nanoparticles affected the crystal structure of diamond deposited for 8 h. Confirmation of various carbon allotropes provides new insight into the nanodiamond synthesis in the gas phase and the growth mechanism of HFCVD diamond.

Negatively charged diamond nanoparticles are known to be generated in the gas phase of the hot filament chemical vapor deposition (HFCVD) process. However, the structures of these nanoparticles remain unknown. Also, the effect of charging on the stability of nanodiamond structures has not been studied experimentally. Here, by installing a capturing apparatus in an HFCVD reactor, we succeeded in capturing nanoparticles on the floating and grounded SiO, carbon, and graphene membranes of a copper transmission electron microscope grid during HFCVD. We examined the effect of charge on the crystal structure of nanodiamonds captured for 10 s under various conditions and identified four carbon allotropes, which are i-carbon, hexagonal diamond, n-diamond, and cubic diamond, by analyzing 150 d-spacings of ∼100 nanoparticles for each membrane. Nanoparticles captured on the floating membrane consisted mainly of cubic diamond and n-diamond, whereas those captured on the grounded membrane consisted mainly of i-carbon. Diamond particles deposited for 8 h on the floating silicon (Si) substrate exhibited an octahedron shape with well-developed facets, and a high-intensity 1332 cm−1 Raman peak, whereas diamond particles deposited on the grounded Si substrate showed a spherical shape partially covered with crystalline facets with a broad G-band Raman peak. These results indicate that charging stabilizes the diamond structure.

Dense yttrium oxyfluoride (YOF) coating was successfully deposited by suspension plasma spraying (SPS) with coaxial feeding. After deposition for 6 min at a plasma power of 105 kW, the thickness of the YOF coating was 55 &plusmn, 3.2 &micro, m with a porosity of 0.15% &plusmn, 0.01% and the coating rate was ~9.2 &micro, m/min. The crystalline structure of trigonal YOF was confirmed by X-ray diffractometry (XRD). The etching behavior of the YOF coating was studied using inductively coupled CHF3/Ar plasma in comparison with those of the Al2O3 bulk and Y2O3 coating. Crater-like erosion sites and cavities were formed on the whole surface of the Al2O3 bulk and Y2O3 coating. In contrast, the surface of the YOF coating showed no noticeable difference before and after exposure to the CHF3/Ar plasma. Such high resistance of the YOF coating to fluorocarbon plasma comes from the strongly fluorinated layer on the surface. The fluorination on the surface of materials was confirmed by X-ray photoelectron spectrum analysis (XPS). Depth profiles of the compositions of Al2O3, Y2O3, and YOF samples by XPS revealed that the fluorination layer of the YOF coating was much thicker than those of Al2O3 and Y2O3. These results indicate that if the inner wall of the semiconductor process chamber is coated by YOF using SPS, the generation of contamination particles would be minimized during the fluorocarbon plasma etching process.

Non-classical crystallization suggests that crystals can grow with nanoparticles as a building block. In this case, the crystallization behavior depends on the size and charge of the nanoparticles. If charged nanoparticles (CNPs) are small enough, they become liquid-like and tend to undergo epitaxial recrystallization. Here, the size effect of SiC CNPs on film crystallinity was studied in the hot-wire chemical vapor deposition process. To do this, SiC nanoparticles were captured under different processing conditions&mdash, in this case, wire temperature, precursor concentration and the filament bias. Increasing the temperature of tungsten wires and decreasing the ratio of (SiH4 + CH4)/H2 reduced the size of the SiC nanoparticles. When the nanoparticles were small enough, an epitaxial SiC film approximately 100-nm-thick was grown, whereas larger nanoparticles produced polycrystalline SiC films. These results suggest that the size of the CNPs is an important process variable when growing films by means of non-classical crystallization.

The possibility that charged nanoparticles (CNPs) are generated in the gas phase during direct current (DC) magnetron sputtering of Ag is studied. Sputtered Ag particles could be captured on an ultrathin amorphous carbon membrane for transmission electron microscopy (TEM) observation. It is confirmed that the average particle size and the total area of deposition under the condition of the positive bias applied to the substrate are bigger than those under the condition of the negative bias applied to the substrate. The results indicate that some of the sputtered Ag particles are negatively charged. To evaluate the contribution of negatively-charged particles to the film growth, Ag thin films were deposited for 30 min on the Si substrate with the substrate biases of &minus, 300, 0 and +300 V and analyzed by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and four-point probe. When +300 V was applied to the substrate, the film growth rate was highest with the film thickness of 85.0 nm, the crystallinity was best with the smallest full width at half maximum (FWHM) value of 0.44 and the resistivity was smallest with 3.67 &mu, &Omega, &middot, cm. In contrast, when &minus, 300 V was applied to the substrate, the film growth rate was lowest with the film thickness of 68.9 nm, the crystallinity was worst with the largest FWHM value of 0.53 and the resistivity was largest with 8.87 &mu, cm. This result indicates that the charge plays an important role in film growth and can be a new process parameter in sputtering.

The recently discovered yttrium oxyfluoride (YOF) coating has been found to be a highly promising plasma-resistant material which can be coated onto the inner wall of the dry etching chambers used in the manufacturing of the three-dimensional stacking circuits of semiconductors, such as vertical NAND flash memory. Here, the coating behavior of the YOF coating which was deposited by suspension plasma spraying was investigated using a high-output coaxial feeding method. Both the deposition rate and density of YOF coatings increased with the plasma power, which was determined by the gas ratio of Ar/H2/N2 and the arc current. The coating thicknesses were 58 &plusmn, 3.4, 25.8 &plusmn, 2.1, 5.6 &plusmn, 0.6, and 0.93 &plusmn, 0.4 &micro, m at plasma powers of 112, 83, 67, and 59 kW, respectively, for 20 scans with a feeding rate of the suspension at 0.045 standard liters per minute (slm). The porosities were 0.15% &plusmn, 0.01%, 0.25% &plusmn, 0.01%, and 5.50% &plusmn, 0.40% at corresponding plasma powers of 112, 83, and 67 kW. High-resolution X-ray diffraction (HRXRD) shows that the major and minor peaks of the coatings which were deposited at 112 kW stem from trigonal YOF and cubic Y2O3, respectively. Increasing the flow rate of the atomizing gas from 15 slm to 30 slm decreased the porosity of the YOF coating from 0.22% &plusmn, 0.03% to 0.07% &plusmn, 0.03%. The Vickers hardness of the YOF coating containing some Y2O3 deposited at 112 kW was 550 &plusmn, 70 HV.

This study is based on the film growth by non-classical crystallization, where charged nanoparticles (NPs) are the building block of film deposition. Extensive studies about the generation of charged NPs and their contribution to film deposition have been made in the chemical vapor deposition (CVD) process. However, only a few studies have been made in the physical vapor deposition (PVD) process. Here, the possibility for Ti films to grow by charged Ti NPs was studied during radio frequency (RF) sputtering using Ti target. After the generation of charged Ti NPs was confirmed, their influence on the film quality was investigated. Charged Ti NPs were captured on amorphous carbon membranes with the electric bias of &minus, 70 V, 0 V, +5 V, +15 V and +30 V and examined by transmission electron microscopy (TEM). The number density of the Ti NPs decreased with increasing positive bias, which showed that some of Ti NPs were positively charged and repelled by the positively biased TEM membrane. Ti films were deposited on Si substrates with the bias of &minus, 70 V, 0 V and +30 V and analyzed by TEM, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray reflectivity (XRR). The film deposited at &minus, 70 V had the highest thickness of 180 nm, calculated density of 4.974 g/cm3 and crystallinity, whereas the film deposited at +30 V had the lowest thickness of 92 nm, calculated density of 3.499 g/cm3 and crystallinity. This was attributed to the attraction of positively charged Ti NPs to the substrate at &minus, 70 V and to the landing of only small-sized neutral Ti NPs on the substrate at +30 V. These results indicate that the control of charged NPs is necessary to obtain a high quality thin film at room temperature.

Three-dimensional (3-D) Monte Carlo simulations of grain growth with sub-boundaries in the presence of precipitates were performed based on the distribution of realistic grain boundary energy data. The simulated grains with sub-boundaries grew abnormally. The simulated and experimental morphologies of the abnormally growing grains in Fe-3%Si steel were compared. The experimental 3-D morphology was reconstructed from serially sectioned images. Both the simulated and experimental 3-D morphologies of abnormally growing grains have highly irregular and complicated shapes whereas both the simulated and experimental 3-D morphologies of normally growing grains have relatively regular and simple shapes. Growth by wetting is responsible for the highly irregular shape of the experimental abnormally growing grains of Fe-3%Si steel as well as for the highly irregular shape of the simulated abnormally growing grains.

The deposition behavior of silicon films by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) was studied by nonclassical crystallization, where the building block of deposition is charged nanoparticles generated in the gas phase of the reactor. To confirm the existence of nanoparticles in the RF-CVD reactor, nanoparticles were captured on the membrane of the transmission electron microscope (TEM) grid under the condition of the DC bias applied to the holder. The capturing behavior of nanoparticles depended on the bias and the conductivity of the membrane. Also, to examine the effect of the bias on the epitaxial growth, films were deposited on the silicon wafer substrate under the condition of the biases of 0, +1000, and −1000 V applied to the substrate holder. A fully epitaxial film could be grown on a silicon wafer at 550 °C under the bias of −1000 V.

In Fe–3%Si steel, the hot rolling process affects not only the hot rolling texture but also the primary recrystallization texture. Here, the effect of asymmetric hot rolling was studied by comparing the difference in the texture evolved between asymmetric and symmetric hot rolling. The effect of asymmetric hot rolling on the texture of primary recrystallized Fe–3%Si steel was also studied. The symmetric hot rolling of Fe–3%Si steel produces a rotated cube texture at the center but Goss and copper textures near the surface. Asymmetric hot rolling tends to produce Goss and copper textures even at the center like the texture near the surface. After primary recrystallization, the dominant texture at the center changes from {001} to {111} and the new texture has a higher fraction of the grains which make the low energy boundary with Goss grains than that of symmetric hot rolling.

In order to study the effect of the uniaxial stress on the development of a cube-on-face texture, two sheet samples were heat treated with different positions to have a different self-load, resulting in a different stress. One specimen was heat treated at 1120 °C for 60 min with the broad face positioned horizontally to the specimen holder and the other specimen was heat treated with the broad face positioned vertically to the specimen holder with the other condition being the same. The former produced a weak {1 0 0} texture, being only 30.9% whereas the latter produced a strong{1 0 0} texture, being 81.1%. We found out that such a texture difference is related to the difference in the nucleation barrier coming from the stress disparity. Based on this understanding, specimens with a different percentage of the {1 0 0} texture could be manufactured. The measurements of magnetic properties showed that the specimen with 78.4% of {1 0 0} and 3.2% of {1 1 1} had B50 = 1.75 and W15/50 = 2.19, but the specimen with 0.7% of {1 0 0} and 81.3% of {1 1 1} had B50 = 1.61 and W15/50 = 2.50. The results show that the magnetic flux density of B50 was increased by 8.7% and the eddy current loss of W15/50 was decreased by 12.4% due to the evolution of the {1 0 0} texture.

The deposition behavior of silicon films by hot wire chemical vapor deposition (HWCVD) was approached by non-classical crystallization, where the building block of deposition is a nanoparticle generated in the gas phase of the reactor. The puzzling phenomenon of the formation of an amorphous incubation layer on glass could be explained by the liquid-like property of small charged nanoparticles (CNPs), which are generated in the initial stage of the HWCVD process. Using the liquid-like property of small CNPs, homo-epitaxial growth as thick as ~150 nm could be successfully grown on a silicon wafer at 600 °C under the processing condition where CNPs as small as possible could be supplied steadily by a cyclic process which periodically resets the process. The size of CNPs turned out to be an important parameter in the microstructure evolution of thin films.

In this study, acetone was used as a carbon source to deposit diamond films using tantalum filaments by hot filament chemical vapor deposition (HFCVD). For acetone fluxes of 80, 90, 130 and 170 standard cubic centimeters per min (sccm) and the respective hydrogen fluxes of 420, 410, 370, and 330 sccm, film thickness appeared to increase with increasing acetone, and high quality diamonds were deposited with well-defined facets of (111) and (100). For acetone fluxes of 210 and 250 sccm and the respective hydrogen fluxes of 290 and 250 sccm, however, the diamond quality was degraded with cauliflower-shaped structures evolving and the film thickness decreased with increasing acetone. The degradation of diamond quality was confirmed by Raman spectra and X-ray diffraction (XRD). Many diamond crystals grown at acetone fluxes of 80, 90, 130 and 170 sccm consisted of five (111) facets, indicating an icosahedral structure. At the corner where the five (111) facets met, there were pentagonal dimples, which implied that diamond crystals must have been etched. The decrease in film thickness at high acetone fluxes of 210 and 250 sccm also implied that the deposited film must have been etched. These results indicate that the two irreversible processes of deposition and etching occur simultaneously, which would violate the second law of thermodynamics from the classical concept of crystal growth by an individual atom. These puzzling results could be successfully explained by non-classical crystallization, where the building blocks for diamond films are nanoparticles formed in the gas phase.

Evolution of abnormally growing Goss grains in Fe-3%Si steel was observed time sequentially by electron backscattering diffraction (EBSD). For example, some specimens were heated at 1080oC for 5 min, then cooled, polished and observed by EBSD, whose procedure was repeated for 6 times. Highly irregular growth of Goss grains produced island and peninsular matrix grains. Once matrix grains became island or peninsular grains, they shrank much faster than before. This means that these grains were not formed by their low grain boundary mobility but formed by solid-state wetting. Also, grains trapped by impingement of abnormally-growing Goss grains shrank much faster.

When any sample is heat treated, it is normally placed on a supporting material. Such physical contact is not expected to affect the microstructure evolution of the sample. In this study, however, the physical contact between Fe-1%Si sheet and the Al2O3 plate was found to have a strong effect on the evolution of a cube-on-face texture during heat treatment, producing as much as 76.0% when determined by the orientation within {100} ±15o. The similar result was obtained for the tungsten and quartz plates. The results provide a promising method to produce the high efficiency Si steel with a cube-on-face texture.