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• Activation temperature of B-doped Si in sputter epitaxial growth is investigated. • B activation temperature depends on the crystallographic orientation of Si targets. • B activation begins at 560 °C with a (001) target and at 680 °C with a (111) target. • P activation begins at around 250 °C, regardless of the (001) and (111) targets. We have investigated the effect of the crystallographic orientation of B-doped Si (p-Si) crystalline targets on the activation temperature of B dopants in Si epitaxial layers grown on Si(001) substrates by the sputter epitaxy method. Specifically, we compared p-Si targets with two different surface orientations, (001) and (111). We found that the activation temperature depended on the crystallographic orientation of the B-doped p-Si target and B impurities began to be activated at a growth temperature of 680 °C when using the p-Si(111) target and at 560 °C, which is 120 °C lower, when using the p-Si(001) target. This phenomenon is discussed in this paper in terms of the difference in the level of crystallographic plane matching between the growth and target surfaces and the associated energetic barrier to B-atom activation. The case of P-doped Si (n-Si) was also compared, which showed no indication of target crystallographic orientation dependence, when comparing n-Si(001) and n-Si(111) targets, and the P activation began at around 250 °C. These findings are considered associated with P being more easily incorporated into Si lattice than B. The hole Hall scattering factors and estimated drift mobilities obtained with the p-Si(111) target were comparable to previously reported values, whereas those obtained with the p-Si(001) target were 0.17 and 15–23 % lower, respectively, suggesting that the p-Si layers grown using the p-Si(001) target had slightly more defects, possibly owing to lower growth temperatures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Feathery nanoporous Mg, consisting of submicron pores and nanopores, was successfully synthesized by ethyl alcohol assisted physical vapor deposition. • The introduction of ethyl alcohol vapor under vacuum condition is crucial for the formation of feathery nanoporous Mg. • A vacancy-assisted formation mechanism is proposed to explain the formation of feathery nanoporous Mg. Nanoporous magnesium exhibits outstanding performance in hydrogen absorption and desorption, rendering it a promising candidate for hydrogen storage applications. Nevertheless, there is limited discussion on the preparation method and growth mechanism of nano-porous magnesium. In this paper, a novel nanoporous magnesium material characterized by a feathery morphology was successfully synthesized at 823 K for 2 h under a vacuum pressure of 3 Pa, assisted by ethanol vapor through the physical vapor deposition method. The ethanol vapor was identified as the crucial factor in the synthesis of the feathery nanoporous magnesium. A vacancy-assisted formation mechanism is proposed to elucidate the creation of feathery nanoporous magnesium, whereby the ethanol vapor occupies specific positions within the magnesium vapor, resulting in the formation of nano and submicron pores. [ABSTRACT FROM AUTHOR]

• BiI 3 -graphene structure was grown via nucleation and post-growth from the vapor. • Uniform and aligned structures few nanometers in thickness were obtained. • At nanometers thicknesses, the (0 0 3) reflection shifts to smaller angles and broadens. • The band gap of the thinnest structures agrees with the theoretical prediction. • The BiI 3 -gr fits into the 2D material universe, similar to other materials. In recent years, a multitude of 2D materials has been extensively studied, and new ones continue to emerge. Among these, bismuth tri-iodide-graphene material has been reported in both theoretical and experimental studies, displaying intriguing properties. These findings suggest potential photovoltaic applications for BiI 3 layers and van der Waals superstructures. In this context, the present work explores the growth of van der Waals superstructures BiI 3 –graphene, obtained through physical vapor deposition. These structures are achieved by nucleating BiI 3 and allowing it to grow on graphene-covered TEM grids and ultra-flat silicon substrates. When the structures are directly grown on grids and substrates covered with graphene, twisted BiI 3 structures are formed, leading to Moiré interference, indicating the presence of two or more BiI 3 layers and non-uniformity. However, when the structures are grown on grids pre-treated with UV/O 3 , and then subjected to annealing and post-growth, they become more uniform and aligned, without observable twisting. Structures obtained on substrates with this treatment and post-growth result in thinner layers, as thin as 7.59 ± 0.16 nm, with a roughness of 0.435 ± 0.018 nm. As the thickness decreases, the position of the (0 0 3) reflection peak in the diffraction pattern shifts to lower values and broadens, indicating an expansion of the cell along the c -axis. The obtained bandgap values, ranging from 1.55 ± 0.04 to 1.62 ± 0.04 eV, closely align with theoretical predictions. The obtained structures become part of the 2D universe of other similar materials, such as TMDs-graphene, and open up exciting possibilities for new properties and applications. [ABSTRACT FROM AUTHOR]

Ordered arrays of self-assembled ErSi2-x, SmSi2-x, and DySi2-x nanowires aligned along Si [110] have been grown at 600°C on Si(001) vicinal substrates. The nanowires grow perpendicular to the Si dimer rows and are 1.5-5nm wide, approximately 2 monolayers high and up to 1μm long. These nanowires were characterized in situ with scanning tunneling microscopy. © 2002 Elsevier Science B.V. All rights reserved.

• The highly crystalline tellurium doped ZnO nanowires photodetector is fabricated. • The PL studies of these nanowires showed a strong emission peak in the green region. • The photoconducting measurement was performed under field effect transistor principles. • Photodetector showed the dynamic response of an on/off current ratio of around 102. • Carrier concentrations change in fixed V G increased by 1.27 × 1018 cm−3 in 500 nm light. In this paper, the stable and reproducible tellurium doped ZnO nanowires (Te-ZnO NWs) photodetector with intensive responsively is presented. The Te-ZnO NWs were fabricated by physical vapor deposition (PVD) growth mechanism. Field emission scanning electron microscope (FESEM) images showed that the fabricated nanowires were 50 nm in diameter and several microns in length. The high resolution transmission electron microscopy indicated that the synthesized nanowires were crystalline and their phase characterization was validated by the X-ray diffraction (XRD). The photoluminescence (PL) studies of these nanowires showed a strong photoluminescence (PL) emission peak in the green region. It was verified that the optical band gap of the NWs films increased as the Te concentration increased. The photo-conducting measurements were performed under field effect transistor principles. The tellurium doped ZnO nanowires photodetector showed the dynamic response of an on/off current contrast ratio of around 102. The carrier concentrations change in the fixed gate voltage was increased by 1.27 × 1018 cm−3 after 500 nm wavelength light illumination. The photocurrent studies of the samples showed that tellurium doped ZnO nanowires were the suitable photodetector. [ABSTRACT FROM AUTHOR]

• Ag particles in decahedral (D 5 h symmetry) and icosahedral (I h symmetry) habits were grown from vapor. • The possible mechanisms for the formation and morphology evolution were discussed. • Icosahedral Ag particle of perfect symmetrical morphology was grown up to a size of ∼15 μm. • Ten distinct morphology evolution pathways have been identified. Five-fold symmetry is prohibited in crystals following the crystallographic restriction theorem, but tiny particles of materials such as some noble metals formed via vapor condensation are often found in icosahedral or decahedral habits since nucleation occurs around a local center, and the point groups I h and D 5 h are close to the spherical symmetry. This inconsistency then has to be resolved by the growing particles. Here we report the growth of decahedral (D 5 h symmetry) and icosahedral (I h symmetry) twinned silver particles from vapor phase, and identification of morphology evolution pathways on the way growing from roughly 0.1 μm up to 15 μm as a consequence of competition between intrinsic strain mainly out of symmetry misfit and extrinsic surface energy of different facets. The possible detailed mechanism for the individual morphology evolution pathways is discussed. Our results may help clarify the growth mechanism of five-fold twinned crystallites and improve the morphology control of such noble metal particles for targeted applications. [ABSTRACT FROM AUTHOR]

• The structure of the first monolayer depends on the preparation process. • In case of spin coating the nucleation is mediated by edges of the monolayer. • For vapor deposition the nucleation is mediated by confinement with the substrate. • The mosaicity of the thin film crystals are determined by the nucleation process. The benzothieno-benzothiophene derivatives are among the best-performing organic semiconductor materials. Their triumphant application in electronic devices is correlated to their capability to form well-defined thin film structures featuring crystalline order at the substrate–organic interface. Thin films of the molecule 2,7-bis(2-(2-methoxy ethoxy)ethoxy) benzo[b]-benzo[4,5]thieno[2,3-d]thiophene (OEG-BTBT) are prepared by spin coating and physical vapor deposition using different experimental conditions. Atomically flat silicon oxide surfaces with defined surface energies are used as substrates. The crystalline morphology is studied for the monolayer regime up to thick films by X-ray reflectivity, grazing incidence X-ray diffraction and atomic force microscopy. Depending on the preparation process, substantial variations are found in the structure of the first monolayers. The highly flexible oligoethylene glycol side chains allow different monolayer formation processes. Also, the subsequent crystal growth strongly depends on the nucleation in the monolayer regime. Here, we observe two distinct nucleation scenarios, one directly at the substrate surface and one at the edges of sub-monolayer terraces. As a consequence, the mosaicity of the crystallites in thick films is strongly affected by the growth type. This work illustrates that different thin film preparation processes can result in different nucleation mechanisms for subsequent crystallization. Consequently, variations in the crystallographic order in device relevant films are observed. [ABSTRACT FROM AUTHOR]

• Magnesium physical and chemical vapor sources can intercalate epitaxial graphene. • Chemical vapor deposition reduces graphene surface metal contamination. • Physical vapor deposition allows greater intercalated metal quantities. • Magnesium is an air stable n-type dopant of epitaxial graphene. Intercalation of Mg into epitaxial graphene was investigated using chemical vapor deposition (CVD) and physical vapor deposition (PVD) for the formation of n-type doped graphene. Scanning electron microscopy and atomic force microscopy indicate PVD has significantly greater metal deposition and surface roughness compared to the CVD process. Findings from x-ray photoelectron spectroscopy infer the formation of Mg intercalated quasi-freestanding epitaxial graphene indicated by shifting of the SiC peak in C 1s spectra. This is substantiated by visual evidence from scanning tunneling electron microscopy of one or more layers of Mg residing underneath EG. Furthermore, an invariant 2D peak position in Raman spectra taken over a 7-day period in ambient conditions support arguments of the stability of electron doped Mg-intercalated epitaxial graphene. CVD offers a cleaner and smoother surface compared to PVD due to improved control over when the substrate is subjected to Mg exposure, but PVD allows for greater Mg concentrations per minute that may increase the amount of intercalated metal. [ABSTRACT FROM AUTHOR]

Highlights • Growth of Al 1−x Sc x N bulk single crystals. • Substrate for AlGaN based UVB optoelectronic devices. • Sublimation by physical vapor transport (PVT). • Aluminum scandium nitride alloy growth. Abstract We describe the preparation of wurtzite Al 1−x Sc x N bulk single crystals by physical vapor transport by introducing scandium to the aluminum nitride (AlN) source material. The Al 1−x Sc x N single crystals obtained exhibit a maximum scandium atomic concentration of about x = 0.55% in axial c-direction while being uniform within the c-plane. The high structural quality as determined by high resolution x-ray diffraction is comparable to that of AlN bulk crystals. However, the incorporated scandium concentration is about 15 times lower than expected from thermodynamic considerations. This behavior is ascribed to a pronounced scandium segregation or agglomeration in the gas phase and parasitic deposition/loss of ScN during growth. [ABSTRACT FROM AUTHOR]

N-type 4H-SiC crystals were grown by the physical vapor transport (PVT) method with nitrogen and aluminum (N–Al) co-doping. By using aluminum carbide powder preannealed in nitrogen gas atmosphere as an aluminum doping source, we obtained highly N–Al co-doped crystals with a nitrogen concentration higher than that in nitrogen-only-doped crystals. The dislocation densities of N-Al co-doped crystals with a high aluminum concentration (>1 × 10 19  cm −3 ) were found to become higher than those with a low aluminum concentration (<1 × 10 19  cm −3 ). Moreover, we investigated the expansion velocities of double Shockley-type stacking faults (DSFs) in the N–Al co-doped and the nitrogen-only-doped crystals. We found that the DSF expansion velocities in the N–Al co-doped crystals were lower than those in the nitrogen-only-doped crystals. This difference in the DSF expansion velocity is discussed with respect to the quantum well action model. [ABSTRACT FROM AUTHOR]

The growth of n-type 4H-SiC crystals has been performed by physical vapor transport (PVT) growth method, with nitrogen and boron (N-B) co-doping. It was revealed that, in the growth of 4H-SiC with N-B co-doping, the generation of double Shockley-type stacking faults (DSSFs) was suppressed, as in the case of the nitrogen and aluminum co-doping. The resistivity of the N-B co-doped 4H-SiC was as low as 5.5 mΩcm. In addition, we investigated the expansion velocities of DSSFs, which were intentionally caused by indention of crystal surfaces with a diamond indenter, while the crystals were annealed for 2 h at 1000 °C. The DSSF expansion velocities of the N-B co-doped crystals were found to be lower than the velocities of nitrogen doped crystals. The difference in expansion velocities is discussed in terms of the quantum well action model. [ABSTRACT FROM AUTHOR]

We propose a crystalline film growth technique for organic materials called vaporized film deposition (VFD). This method consists of two simple step: vapor-depositing a microcrystalline film on a substrate, then transferring it on another substrate by heating in vacuum. In this study, we used a cyano-substituted π-conjugated oligomer, 5,5’-bis(4’-cyanobiphenyl-4-yl)-2,2’-bithiophene (BP2T-CN). By placing the two substrates with a spacing of <1 mm at 250 °C, the BP2T-CN film was vaporized and transferred into a polycrystalline film composed of single-crystal grains with a size of 5–20 µm. This method enabled us to fabricate homogeneous polycrystalline films under controlled thickness. Consequently, we observed optically pumped lasing from this polycrystalline film based on light confinement in each grain. [ABSTRACT FROM AUTHOR]

Effects of the nature of substrates, either crystalline or non-crystalline, on the structure and properties of ZnO films deposited by sputtering were investigated. This study focuses mainly on the role of the external electric bias applied to substrates during magnetron sputtering deposition in controlling crystalline polarity, i.e., Zn-face or O-face, and the resulting film properties. It was found that polarity control was achieved on silica and silicon substrates but not on sapphire substrates. The substrate bias did influence the lattice parameters in the structural formation; however, the selection of the substrate type had a significant influence on the defect structures and the film properties. [ABSTRACT FROM AUTHOR]

We recently reported on the formation of overlapping rhombus-shaped stacking faults from scratches left over by the chemical mechanical polishing during high temperature annealing of PVT-grown 4H–SiC wafer. These stacking faults are restricted to regions with high N-doped areas of the wafer. The type of these stacking faults were determined to be Shockley stacking faults by analyzing the behavior of their area contrast using synchrotron white beam X-ray topography studies. A model has been proposed to explain the formation mechanism of the rhombus shaped stacking faults based on double Shockley fault nucleation and propagation. In this paper, we have experimentally verified this model by characterizing the configuration of the bounding partials of the stacking faults on both surfaces using synchrotron topography in back reflection geometry. As predicted by the model, on both the Si and C faces, the leading partials bounding the rhombus-shaped stacking faults are 30 ° Si-core and the trailing partials are 30 ° C-core. Using high resolution transmission electron microscopy, we have verified that the enclosed stacking fault is a double Shockley type. [ABSTRACT FROM AUTHOR]

Synchrotron X-ray Topography is a powerful technique to study defects structures particularly dislocation configurations in single crystals. Complementing this technique with geometrical and contrast analysis can enhance the efficiency of quantitatively characterizing defects. In this study, the use of Synchrotron White Beam X-ray Topography (SWBXT) to determine the line directions of threading dislocations in 4H–SiC axial slices (sample cut parallel to the growth axis from the boule) is demonstrated. This technique is based on the fact that the projected line directions of dislocations on different reflections are different. Another technique also discussed is the determination of the absolute Burgers vectors of threading mixed dislocations (TMDs) using Synchrotron Monochromatic Beam X-ray Topography (SMBXT). This technique utilizes the fact that the contrast from TMDs varies on SMBXT images as their Burgers vectors change. By comparing observed contrast with the contrast from threading dislocations provided by Ray Tracing Simulations, the Burgers vectors can be determined. Thereafter the distribution of TMDs with different Burgers vectors across the wafer is mapped and investigated. [ABSTRACT FROM AUTHOR]

Bi 2 Se 3 thin films were grown on c -plane sapphire substrates by hybrid physical-chemical vapor deposition (HPCVD) using trimethyl bismuth (TMBi) and Se pellets. A Se-rich environment is created by evaporating Se pellets in the vicinity of the substrate, which is used to suppress the formation of Se vacancies. The effects of pre-cracking temperature and substrate/Se temperature on the growth rate, structural and electrical properties of the Bi 2 Se 3 films were investigated. C -axis oriented films were obtained which show a reduction in the carrier concentration as pre-cracking temperature was increased from 290 °C (1.6×10 19 cm −3 ) to 350 °C (8.4×10 18 cm −3 ). An additional reduction in carrier concentration (7.28×10 18 cm −3 ) was observed on increasing the substrate temperature from 200 to 260 °C. [ABSTRACT FROM AUTHOR]

Single crystals of mercurous halide were grown by physical vapor transport method (PVT). The orientation and the crystalline quality of the grown crystals were determined using high resolution x-ray diffraction (HRXRD) technique. The full width at half maximum (FWHM) of the grown mercurous bromide crystals was measured to be 0.13 degrees for (004) reflection, which is the best that has been achieved so far for PVT grown mercurous halide single crystals. The extended defects of the crystals were also analyzed using high resolution x-ray diffraction topography. Preliminary studies were carried out to evaluate the performance of the crystals on acousto-optic modulator (AOM) and gamma-ray detector applications. The results indicate the grown mercurous halide crystals are excellent materials for acousto-optic modulator device fabrication. The diffraction efficiencies of the fabricated AOM device with 1152 and 1523 nm wavelength lasers polarizing parallel to the acoustic wave were found to be 35% and 28%, respectively. The results also indicate the grown crystals are a promising material for gamma-ray detector application with a very high energy resolution of 1.86% FWHM. [ABSTRACT FROM AUTHOR]

The pigment 6,6′-dibromoindigo (Tyrian purple) shows strong intermolecular hydrogen bonds and the film formation is, therefore, expected to be influenced by the polar character of the substrate surface. Thin films of Tyrian purple were prepared by physical vapor deposition on a variety of substrates with different surface energies: from highly polar silicon dioxide surfaces to hydrophobic polymer surfaces. The crystallographic properties were investigated by X-ray diffraction techniques such as X-ray reflectivity and grazing incidence X-ray diffraction. In all cases, crystallites with “standing” molecules relative to the substrate surface were observed independently of the substrate surface energy. In the case of polymer surfaces, additional crystallites are formed containing “lying” molecules with their aromatic planes parallel to the substrate surface. Small differences in the crystallographic lattice constants were observed as a function of substrate surface energy, the corresponding small changes in the molecular packing are explained by a variation of the hydrogen bond geometries. This work reveals that despite the limited influence of the surface energy on the molecular orientation, the crystalline packing of Tyrian purple within thin films is altered and slightly different structures form. [ABSTRACT FROM AUTHOR]

High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi 2 Te 3 and Bi 2 Se 3 . However, ternary phases of Bi 2 Te 3− y Se y with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi 2 Te 2.9 Se 0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi–Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form. [ABSTRACT FROM AUTHOR]

The continuous laterally aligned growth of In 2 O 3 nanocrystal networks extended with nanowire and pyramid connections under annealing influence has been reported. These nanostructures have been grown on Si substrate by using oxygen-assisted annealing process through PVD growth technique. The formation of In 2 O 3 nanocrystals has been achieved by the successive growth of critical self-nucleated condensation in three orientations. The preferred direction was the route between two pyramids especially in the smallest surface energy. The effects of substrate temperature in annealing process on the morphological properties of the as-grown nanostructures were investigated. The annealing technique showed that by controlling the surface energy, the morphology of structures was changed from unregulated array to defined nanostructures; especially nanowires 50 nm in width. The obtained nanostructures also were investigated by the (transmission electron microscopy) TEM, Raman spectrum and the (X-ray diffraction) XRD patterns. They indicated that the self-assembled In 2 O 3 nanocrystal networks have been fabricated by the vapor–solid (VS) growth mechanism. The growth mechanism process was prompted to attribute the relationship among the kinetics parameters, surface diffusion and morphology of nanostructures. [ABSTRACT FROM AUTHOR]

Magnesium nanowires were successfully prepared by a physical vapor deposition method, and influence factors on the formation of magnesium nanowires were discussed based on the evaporation/deposition temperature, vacuum level, magnesium vapor concentration and deposition time. The results show that the formation of magnesium nanowires occurs within a specific evaporation/deposition temperature range. Magnesium nanowires become thicker and longer and finally convert into magnesium micronparticles with the increase of evaporation temperature or decrease of deposition temperature. The vacuum level also plays a decisive role in the formation of magnesium nanowires that magnesium nanowires can only be prepared in a high vacuum level. The magnesium vapor concentration and deposition time also have significant influences on the formation of magnesium nanowires. A distribution map of magnesium nanowire is set up based on our experimental results and a criterion of supersaturation of magnesium vapors is proposed in the explanation of the formation of magnesium nanowires. [ABSTRACT FROM AUTHOR]

Surface morphologies on the (000 1 ¯ ) C facet of 4H–SiC boules grown using the physical vapor transport method were examined in various scales (from millimeter to nanometer) using different types of microscopies such as differential interference contrast (DIC) optical microscopy and atomic force microscopy (AFM). DIC optical microscopic observation revealed that there are three distinct morphological regions at the growth front of the 4H–SiC boules: the facetted region, non-facetted region and intermediate region between them. The local inclination of the facet surface from the {0001} basal plane increases toward the edge of the facetted region and then decreases in the intermediate region. AFM observations revealed that characteristic step structures were established in these two regions and that nitrogen doping significantly influenced the stability of the step structures. Based on the results, the formation mechanism of surface morphologies on the (000 1 ¯ ) C facet of 4H–SiC boules is discussed. [ABSTRACT FROM AUTHOR]

Temperature-dependent molecular orientations in the initial growth processes of pentacene on amorphous SiO 2 surface with different substrate temperatures have been investigated using molecular dynamics simulations. As the substrate temperature ranges from 270 K to 600 K, there exists a transition behavior for pentacene cluster from the normal-oriented, ordered configuration to the lateral-oriented, disordered one as measured by the decreased average orientation angle and order parameter, showing the significant effect of the substrate temperature on the molecular orientation. The transition behavior is related to the strength relationship between molecule–molecule interactions and molecule–substrate interactions. During the optimal temperature range between 300 K and 350 K, the pentacene molecules tend to form the normal-oriented, well-ordered cluster driven by the dominant molecule–molecule interactions, which is affected by the substrate temperature in a greater degree than the molecule–substrate interactions. When the temperature is lower than 300 K, the ordering of pentacene cluster becomes a little worse. A higher substrate temperature results in the lateral orientation with the weakening of the molecule–molecule interactions. Then the further intensification of molecular thermal motion gradually makes the molecules separate from the cluster or the substrate surface, resulting in the appearance of the undesirable separated configuration. [ABSTRACT FROM AUTHOR]

We demonstrate tin (Sn) nanowires growth enhanced by Selenium (Se) atoms via physical vapor transport (PVT) method. The Raman spectroscopy, X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy show that Sn nanowires are synthesized with a large quantity, good quality and high purity of Sn. The growth of Sn nanowires is attributed to Solid–Vapor–Liquid mechanism. The effects of gold nanoparticles catalyst, Si substrate, and Se atoms on Sn nanowires growth are discussed in detail. We find that Se atom plays a key role in the growth of Sn nanowires. The gaseous Sn atoms are absorbed by the eutectic alloy droplets of Se–Au at first. Then Sn atoms precipitate at the liquid–solid phase interface due to a supersaturated solution and form a one-dimensional nanostructure. In all, this PVT method could provide a simple and quick way to synthesize monocrystalline Sn nanowires with an advantage in both quality and quantity. The optical transmittance of Sn nanowires thin film with 2 μm 2 density approaches 85–90% in visible wavelength. Therefore, the Sn nanowires thin film can be applied to transparent electrode along with their metallic property. [ABSTRACT FROM AUTHOR]

While it is being debated whether Cd vacancy is an effective p-dopant in CdTe, and whether CdTe thin film in solar energy application should be Cd-deficient or Cd-rich, in the theory of CdTe physical vapor deposition (PVD) it has been assumed that both the source material and the thin film product is stoichiometric. To remediate the lack of effective theory, a new PVD model for CdTe photovoltaic (PV) modules is presented in this work, in which the composition of the CdTe thin film under growth is a parameter determined by the source CdTe composition as well as the growth condition. The solid phase Cd 1− δ Te 1+ δ compound under deposition temperature is treated as a solid solution with a mole of excess pure Te or Cd as solute and one mole of congruently grown CdTe as solvent. Assuming that the vapor pressure of Te 2 can be calculated by using the law of solid solution P Te = H 0 + aH 1 + a 2 H 2 round the congruent composition, where the molar number a and the constants H 0 , H 1 and H 2 as functions of temperature T are extracted from the experimental data. Thus, the mole fraction of solute in the grown CdTe thin film as well as the growth rate, as a function of the solute mole fraction in the source CdTe can be determined. [ABSTRACT FROM AUTHOR]

X-ray diffraction imaging (topography) has been used in monochromatic beam mode to demonstrate that 100 mm diameter ZnTe crystals, several millimetres thick, and grown by the multi-tube physical vapour transport technique on (001) and (211B) GaAs substrates, have very high crystal perfection. Images taken in the Bragg geometry from planes containing the growth direction show evidence of cellular dislocation structure and give strong contrast from the whole, several mm 2 , sample area. Rocking curves taken from small areas show only moderate broadening from that expected from a perfect crystal, indicating dislocation density of typically 3.5×10 6 cm −2 close to the seed and 3.3×10 5 cm −2 at the top of the grown crystal. At the top surface, planes parallel to the seed show biaxial concavity, a feature attributed to the ZnTe boule bowing under tensile strain generated at the substrate-crystal interface due to the mismatch in thermal expansion coefficients of GaAs and ZnTe. Crystals grown on (211B) substrates are of {331} orientation, showing no evidence of twin boundaries, suggesting that {331} growth is initiated at, or very close to, nucleation. [ABSTRACT FROM AUTHOR]

Scandium is introduced into bulk SiC during the physical vapor transport (PVT) growth. SiC crystals grown with different Sc contents (from 0.5 wt% up to 2.5 wt%, added to the SiC source material) are studied. Magnetic properties of SiC doped with scandium during the PVT growth are reported for the first time. The presence of antiferromagnetic interactions between magnetic moments of Sc ions is concluded from the temperature dependence of magnetic susceptibility. Detailed PL spectra of 4H-/6H-SiC:B and 4H-/6H-SiC:Sc crystals are presented. A new energy level of 35–37 meV is found on SiC:Sc samples and its possible assignment to a complex defect, consisting of nitrogen donor and scandium acceptor, is proposed. [ABSTRACT FROM AUTHOR]

Indium monotelluride (InTe) crystals were grown from vapour phase under different temperature gradients by employing physical vapour deposition (PVD) method. The morphology of these crystals such as whiskers, needles, platelets etc., strongly depends on the temperature distribution in the horizontal dual zone furnace. InTe platelets were deposited by setting the temperature of the charge ( T C ) and growth ( T S ) zones at 1073 K and 773 K (Δ T =300 K), respectively, for different growth periods (24 h, 48 h, 72 h and 96 h). The surface growth features have been analyzed by scanning electron microscopes, which indicate layer growth mechanism for all the crystals. Various crystals grown under Δ T =200 K and 300 K (retaining T S invariant) were examined by X-ray diffraction and elemental analysis. InTe samples exhibited consistent lattice parameters, density and atomic percentage, establishing stoichiometry and chemical homogeneity. The results obtained for Seebeck coefficient, electrical conductivity, power factor, dislocation density and microhardness are found to be reproducible as well. The vapour deposited InTe platelets are mechanically stable and possess high value of TEP, which ensure their practical application in thermoelectric power generation. [ABSTRACT FROM AUTHOR]

This study describes the transformation of molecular orientation which has a significant effect on the charge carrier mobility of organic thin film transistors. Theoretical analyses and molecular dynamics simulations are performed to uncover the mechanism of the orientation transformation of pentacene molecules on the amorphous SiO 2 surface during the early stage of the physical vapor deposition process, where the initially grown lateral-oriented cluster will transfer to the normal-oriented one at a critical size n c . The reorientation behavior is related to the competition between the molecule-molecule interactions and the molecule-substrate interactions. For small size clusters, the pentacene molecules are found to prefer to form a lateral-oriented cluster as driven by the molecule-substrate interactions, which can be increased by the existence of the sylanol groups on the amorphous SiO 2 surface. Furthermore, when the molecular number n is greater than n c , the normal orientation in the herringbone structure is gradually formed and becomes the stable configuration because the molecule-molecule interactions is dominant. [ABSTRACT FROM AUTHOR]

Crystals of ε-phase tris(8-hydroxyquinoline) aluminum (ε-Alq 3 ) were prepared by using physical vapor deposition (PVD) method in a double zone tube furnace. The structural properties of the ε-Alq 3 crystals were investigated by using an X-ray single crystal diffractometer (XSCD) and a high resolution scanning electron microscope (SEM). Large straight steps were observed from the side face of the pine needle-like crystals. The straight steps are parallel with each other like terraces and the widths of the steps are fixed, indicating that the ε - Alq 3 crystals may have layered structures. The photoluminescence (PL) spectra at different temperatures (7 K, 66 K, 220 K, 300 K and 350 K) and the absorption spectrum were also investigated. The optical band gap of the ε-Alq 3 crystals was calculated to be about 2.82 eV. This value is a little larger than that of amorphous mer -Alq 3 (about 2.7 eV), indicating a minimizing of impurities, grain boundaries and defects. [ABSTRACT FROM AUTHOR]

SiC crystals grown by a Physical Vapor Transport (PVT) method in the presence of varying Ce impurity contents (from 0.1 wt% up to 2.5 wt%) added to SiC source material are investigated. The presence of the cerium vapor in the growth atmosphere is confirmed by X-ray photoelectron spectroscopy measurements. Different electrical properties of SiC crystals are obtained while use was made of non-oxide (CeSi2) or oxide (CeO2) sources of Ce impurity. The impact of cerium on low concentrations of boron atoms in bulk SiC is reported. Presence of Ce in the vapor stabilizes the growth of the 4H-SiC polytype. [ABSTRACT FROM AUTHOR]

Ag modified thin films were grown by sputtering method using Ag/TiO2 target. Target was sintered using Spark Plasma Sintering (SPS) method from Ag and TiO2 powders. Sputtering was done on glass at room temperature using RF magnetron sputter. After deposition samples were calcined at 300 °C, 400 °C and 500 °C in order to obtain tetragonal structure, particularly anatase. Crystal structure properties were investigated using X-ray Diffractometry (XRD). X-ray Photoelectron Spectrophotometer (XPS) was used to analyze chemical composition and ionic state of elements in deposited films. Optical properties of obtained films were determined by UV-visible absorbance spectrophotometer. It was found that 300 nm thick films calcined at 500 °C improved the photocatalytical properties for photodegradation of Rhodamine B (RhB). [ABSTRACT FROM AUTHOR]

Abstract: Physical Vapour Deposition (PVD) provides stoichiometric crystals of different morphology, depending upon the materials, geometry of ampoules, temperature profiles, growth parameters and kinetics of crystallization. The crystal forms such as needles, platelets and spherulites of beta indium sesquitelluride (β-In2Te3) were produced by controlling the temperature of source and growth zones. The X-Ray Diffraction (XRD) and chemical analysis of the spherulitic crystals confirmed zinc blende structure with beta phase. Their resistivity (135.16Ωcm) at room temperature (300K) was determined by van der Pauw method. The temperature dependence of DC conductivity was investigated using the conventional two-probe technique. The variation of dielectric constant (ε 1) and dielectric loss (tan δ) with temperature has been studied for different frequencies (1kHz–1MHz). The AC conductivity, σ ac (ω) was found to vary with angular frequency as ω s , where s is the frequency exponent. The values of s lie very close to unity and show a slight decrease with increase in temperature, which indicate a Correlated Barrier Hopping (CBH) between centres forming Intimate Valence Alternation Pairs (IVAP). The activation energy for conduction ranges from 0.187eV to 0.095eV. The microhardness of β-In2Te3 spherulites is found to be 353.5kg/mm2, which is higher than that of other semiconducting chalcogenides. The results thus obtained on crystals grown from vapour phase open up ample possibilities for radiation detector applications. [Copyright &y& Elsevier]

• The first demonstration of the growth of EuVO 3 films by molecular beam epitaxy (MBE). • Epitaxial strain works effectively to reduce the electrical resistivity of EuVO 3. • Observation of the Eu3+ and V3+ valence states by X-ray absorption spectroscopy. We report the single-crystal thin film growth of EuVO 3 of a Mott insulator with V3+ ( d 2 , S = 1). We used the pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) methods and obtained the well-oriented epitaxial thin films with a pseudo-tetragonal crystal structure of EuVO 3 which is distinct from the orthorhombic structure in bulk. The high quality of EuVO 3 films is verified by the valence state of europium and vanadium ions with X-ray absorption near-edge structure (XANES) measurements showing clear signs from Eu3+ and V3+. The electrical resistivity exhibits the insulating temperature dependence; however, the magnitude of the resistivity is reduced from that of bulk EuVO 3 , possibly due to biaxial strain from substrates. [ABSTRACT FROM AUTHOR]

Abstract: Structural investigation of the seeding process for the physical vapor transport (PVT) growth of 4H–SiC single crystals was conducted by high-resolution x-ray diffraction (HRXRD) and synchrotron x-ray topography. Characteristic lattice plane bending behavior was observed in the near-seed regions of the grown crystals. The bending of the (112̄0) lattice plane was localized near the seed/grown crystal interface, and the (0001) basal plane bent convexly in the growth direction near the interface, indicative of the insertion of extra-half planes pointing toward the growth direction during the seeding process for PVT growth. This study discusses a possible mechanism for the observed lattice plane bending and sheds light on defect formation processes during the PVT growth of 4H–SiC single crystals. [Copyright &y& Elsevier]

Abstract: To dynamically model the plastic deformation of 4H–SiC single crystals during physical vapor transport (PVT) growth, the Alexander–Haasen model, originally proposed for the elemental semiconductor, is extended into IV–IV compound semiconductors. By fitting the model parameters to the experimental data, we show that the Alexander–Haasen model can describe the plastic deformation of 4H–SiC single crystals if the activation of the carbon-core partial dislocation is modeled in the high-temperature region (above 1000°C) and the silicon-core partial dislocation is modeled in the low-temperature region (below 1000°C). We then apply the same model to the dynamical deformation process of a 4H–SiC single crystal during PVT growth. The time evolution of the dislocation density is shown, and the effects of the cooling time on the final dislocation density, residual stress and stacking faults are also examined. [Copyright &y& Elsevier]

Abstract: The effect of nitrogen and aluminum as doped impurities on the stability of SiC polytypes (C- or Si-face 4H and 6H substrates) formed by physical vapor transport (PVT) was investigated. The stability of the polytypes was analyzed using classical thermodynamic nucleation theory with numerical results obtained from a global model including heat, mass and species transfer in a PVT furnace. The results reveal that the formation of 4H-SiC was more stable than that of 6H-SiC when a grown crystal was doped with nitrogen using C-face 4H- and 6H-SiC as seed crystals. In contrast, formation of 6H-SiC was favored over 4H-SiC when Si-face 4H- and 6H-SiC seed crystals were used. Meanwhile, the formation of 4H-SiC was more stable than that of 6H-SiC when aluminum was the dopant and C- and Si-faces of 6H-SiC were used as seed crystals. Formation of 6H-SiC occurred over that of 4H-SiC in the cases of C- and Si-faces of 4H-SiC as seed crystals. [Copyright &y& Elsevier]

Abstract: The physical vapor transport (PVT) method is used to grow silicon carbide (SiC) crystals, which are difficult to be grown by other methods. In this paper, a field-coordination theory is involved to optimize the SiC PVT growth process. By using a finite volume-based computational method, we calculate the flow field as well as species concentration field before and after improvement of the thermal design, respectively. The shape of the SiC crystal grown using the improved thermal design is also shown. [Copyright &y& Elsevier]

Abstract: The effect of the presence of CeO2 in the source material on the properties of SiC crystals grown by Physical Vapor Transport (PVT) method is investigated. The doping efficiency and, indirectly, the presence of the cerium vapour in the growth atmosphere were examined by study of structural, electrical and optical properties of the crystals. X-ray photoelectron spectroscopy shows that Ce2O3 and CeO2 coexist on the SiC post-growth surfaces. A detectable Ce incorporation is observed only in the last grown part of the crystal. [Copyright &y& Elsevier]

Abstract: The current status of the development of the heavy metal iodides as photoconductors for direct and digital imaging is reviewed. The physical properties of these materials are first summarized as regards their application as photoconductors and the growth of their layers onto readout matrixes for digital imaging. A comparison of the results obtained for polycrystalline and oriented layers of mercuric iodide, lead iodide and bismuth tri-iodide, grown by Physical Vapor Deposition (PVD), is presented. The three materials were found to have similar behavior; the influence of layers orientation on electrical properties and on response to radiation is also evaluated. The best results (DQE, MTF, and actual images) reported for devices made with mercuric and lead iodide layers grown onto TFT and CMOS are remarked, and device performance is compared with the one of alternative materials such as a-Se and CdTe. Perspectives of the field such as using nanostructures as precursors for growing epitaxial layers, and possible future research, are also presented. [Copyright &y& Elsevier]

Abstract: We report the growth of highly crystalline GaS tubular structures directly on Ga metal from banana-leaf like structures via a facile catalyst free physical vapor deposition process. GaS microtube arrays with 1.5–2μm length were synthesized by promoting the intrinsic layered crystal structure of GaS during thermal evaporation where the thermal stress and interlayer interactions are mostly dominant. We monitored the growth process systematically to build a proper understanding of the formed tubular structures in this layered material. Microstructural analyses indicate that the GaS microtubes start with the formation of ultra-long, uniform banana-leaf like morphology that eventually splits into thinner flakes and starts rolling in nanometer size diameters. Final realization of GaS microtubes happened by the expansion of these intermediate rolled-up layers in their outer diameter by minimizing the strain energy in the system in a self-catalytic growth process. [Copyright &y& Elsevier]

Abstract: We studied dependence of process parameters, such as temperature of a seed, pressure in a furnace and surface polarity of a substrate, on polytypes of SiC in a process of physical vapor transport. The analysis was based on a classical thermodynamic nucleation theory in conjunction with numerical results obtained from a global model. We investigated which polytype was more stable in the nucleation stage by a comparison of nucleation energies of each polytype. The results show that the formation of 4H-SiC was more stable than that of 6H-SiC when we used C-face SiC as a seed. Furthermore, the most stable polytype could change from 4H-SiC to 6H-SiC in a condition of higher supersaturation, with a condition of higher temperature of a seed and lower pressure in a furnace. Meanwhile, the formation of 6H-SiC was more stable than 4H-SiC when Si-face of a seed was used. [Copyright &y& Elsevier]

Abstract: Growth by the Multi-tube Physical Vapour Transport technique and characterisation of bulk (Cd,Zn)Te is described. The crystalline perfection and uniformity of zinc content have been mapped by infra-red transmission and microscopy, X-ray diffraction and photoluminescence. X-ray double crystal rocking curve full widths at half maximum as low as 43in have been obtained and a mean zinc mole fraction of 0.03 has been found to vary by less than ±0.003 over the diameter of a 50mm boule. The material exhibits a resistivity in the 2×109 range and planar devices fabricated from this material have shown electron mobility lifetime products of 4.07×10−3 cm2 V−1. [Copyright &y& Elsevier]

Abstract: We have investigated the influence of carrier gas on grown gallium nitride (GaN) epitaxial layers deposited on n-Si (111) by a physical vapour deposition (PVD) via thermal evaporation of GaN powder at 1150°C. The GaN nanostructures were grown at a temperature of 1050°C for 60min under various gases (N2, H2 mixed with N2, and Ar2) with absence of NH3. The morphology, structure, and optical properties (SEM) images showed that the morphology of GaN displayed various shapes of nanostructured depending on the type of carrier gas. X-ray diffraction (XRD) pattern showed that the GaN polycrystalline reveals a wurtzite-hexagonal structure with [001] crystal orientation. Raman spectra exhibited a red shift in peaks of E2 (high) as a result of tensile stress. Photoluminescence (PL) measurements showed two band emissions aside from the UV emission. The ultraviolet band gap of GaN nanostructure displayed a red shift as compared with the bulk GaN; this might be attributed to an increase in the defect and stress present in the GaN nanostructure. In addition, the observed blue and green–yellow emissions indicated defects due to the N vacancy and C impurity of the supplied gas. These results clearly indicated that the carrier gas, similar to the growth temperature, is one of the important parameters to control the quality of thermal evaporation (TE)-GaN epilayers. [Copyright &y& Elsevier]

Abstract: The effect of ZnO underlayers on the crystal growth of MgO thin films was investigated. MgO single layers and double-layered coatings consisting of ZnO/MgO were deposited on unheated soda-lime silicate glass substrates by magnetron sputtering. X-ray diffraction measurement revealed that the MgO single layers were poorly crystallized even if the MgO thin films were deposited at various oxygen gas flow ratios and at various gas pressures. Moreover, it was observed that the ZnO/MgO coatings exhibited a preferred orientation along MgO(200) and that well-crystallized MgO thin films with very small thickness (10nm) could be obtained using ZnO underlayers. This improvement in MgO thin films should be caused by heteroepitaxial-like growth of MgO{100} on ZnO{001} crystal lattice planes. In addition, the possible mismatch between MgO and ZnO atomic arrangements was estimated to be 8.2%. [Copyright &y& Elsevier]

Abstract: (Cu, Al)-codoped ZnO films have been prepared by inductively coupled plasma enhanced physical vapor deposition (ICP-PVD) system at different substrate temperatures ranging from room temperature to 527°C. The electrical and magnetic properties, defect and chemical valence state were studied. Room-temperature ferromagnetism was observed in all of the (Cu, Al)-codoped ZnO films. It was found that Cu ions played an important role in the ferromagnetism origin and showed multiple roles in the semi-insulating and conductive regimes according to the Hall effect measurements. For the semi-insulating regime, Cu ions showed mixed valence states of +1/+2 and acted as local charge reservoirs. For the conductive regime, Cu ions showed dominant valence states of +2 and acted as magnetic ions. [Copyright &y& Elsevier]

Abstract: Epitaxial growth of LaB6 (100) thin films was examined on MgO (100) and sapphire (α-Al2O3) (0001) substrates with insertion of a 2–3nm-thick epitaxial SrB6 buffer layer by pulsed laser deposition in ultra-high vacuum. Reflection high-energy electron diffraction, X-ray diffraction, and the Raman scattering spectroscopy measurements proved that the heteroepitaxial structure of the LaB6 (100)/SrB6 (100)/MgO (100) substrate has a single-domain, while and that of the LaB6 (100)/SrB6 (100)/sapphire (0001) substrate have three domains. LaB6 thin films grown without the buffer layer were not epitaxial; instead, they developed as polycrystalline films with a random in-plane configuration. The buffer layer greatly affected the initial growth of the LaB6 thin films. Epitaxial LaB6 thin films exhibited metallic behavior with almost constant resistivities in the temperature range 12–300K. At room temperature, the resistivities of single-domain LaB6 (100) epitaxial thin films on MgO substrates were about 5 times smaller than those of the three-domain LaB6 (100) epitaxial thin films on the sapphire substrates. [Copyright &y& Elsevier]

Abstract: The structural properties of crystalline silicon (Si) films on bare and aluminum-doped zinc oxide (AZO)-coated glass substrates were comparatively investigated by X-ray diffractometer, Raman spectroscopy, and transmission electron microscope. It was observed that for the amorphous Si (a-Si) films on bare and AZO-coated glass substrates subjected to five-step rapid thermal annealing (RTA) at 750°C/60s, they were both polycrystalline in nature and, moreover, the Si characteristic peak intensity of Si films on AZO-coated glass was slightly higher than that of Si films on bare glass, while the crystalline volume fractions of Si films on both substrates were nearly similar. Furthermore, it was revealed that a-Si films on AZO-coated glass can be crystallized when subjected to five-step RTA 750°C/60s, while Zn2SiO4 new phase was formed at RTA temperature of 900°C or higher, which may influence the crystalline Si films property. [Copyright &y& Elsevier]

Abstract: Phenazine–chloranilic acid cocrystal thin films can be formed by vacuum evaporation of the component molecules onto cooled substrates. Fluxes of phenazine and chloranilic acid were provided from separate sublimation sources, from which the cocrystalline phase can be formed under a wide range of impingement rates of the component molecules. Substrates consisted of Au or Ni thin films on Si wafers, cooled to 100–140K during deposition. X-ray diffraction and scanning electron microscopy show that this process yields polycrystalline thin films of the cocrystal with voids between crystalline grains. The relative intensities of X-ray reflections differ from reported intensities of polycrystalline powders, suggesting that the films have an anisotropic distribution of crystallographic orientations. The cocrystalline thin films have an effective dielectric constant of 13 at room temperature, increasing at lower temperatures and exhibiting a broad maximum near 200K. The means to grow thin films of organic ferroelectric materials will allow the integration of new functionalities into organic electronic device structures, including capacitors and field-effect transistors. [Copyright &y& Elsevier]