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SnTe is an important material because of its applications in mid-infrared photo-detectors. In the present work, the effects of film thickness on scaling law and surface properties (i.e., morphologies and optical properties) of SnTe thin films have been investigated. SnTe thin films of different thicknesses are prepared by means of e-beam evaporation technique. The surface morphology of each film is analyzed by atomic force microscopy (AFM) as well as a scanning electron microscope. The crystallinity of the films is found to increase with increasing film thickness, as confirmed by x-ray diffraction and Raman measurements. Fractal analysis is performed on AFM images to investigate the irregularity of surfaces. It is found that the surface of the thicker sample is rougher than the thinner sample. The autocorrelation function is applied to investigate the self-affine fractal nature of surfaces. The average roughness, interface width, lateral correlation length, local surface slope, and fractal dimension increased with film thickness. The values of roughness exponent, growth exponent, dynamic exponent, and steepening exponent are calculated and found to be α = 0.76 - 0.96 , β = 0.75 , z = 1.92 , and λ = 0.35 - 0.25 , respectively. The scaling exponents together with the other parameters such as the local surface slope indicate that the growth is quasi-3D island/mound type with rapid surface roughening behavior and obeys anomalous scaling. The multiple scattering cross sections of light together with Fourier transform infrared spectroscopy data analyses suggest that the higher crystalline film with a smaller number of defects is infrared-sensitive and may be more suitable for advanced mid-infrared detector applications. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate an enhancement of the measured spin Seebeck coefficient in Fe3O4/Pt bilayer films due to an increase in Fe nanodroplets formed by pulsed laser deposition. Four bilayer films were deposited at the same time from a highly textured target, resulting in a general increase in droplet formation that was confirmed to be Fe rich by scanning electron microscope and transmission electron microscope-dispersive x-ray spectroscopy. Of these four films, there were two distinct groupings with differing density of α-Fe droplets, where the bilayer with higher droplet density exhibited a 64% increase in the measured spin Seebeck coefficient from 38 to 63 nV m/W. [ABSTRACT FROM AUTHOR]

Compared to the bulky ceramic counterparts, antiferroelectric (AFE) thin films exhibit higher energy-storage performance. It has been demonstrated that the performance of the AFE thin films is strongly affected by the thickness. However, possible changes in the phase structures and microstructures accompanied by varying thicknesses have been less known, which makes it hard to fully understand the physical insight of the thickness effect. Herein, we fabricate a series of PbZrO3 (PZ) thin films by chemical solution deposition whose thickness is approximately proportional to the number of deposition layers, i.e., one to four layers with each layer of about 60 nm in thickness. The detailed structural characterization has been performed by using x-ray diffraction, a scanning electron microscope, and a transmission electron microscope. The films are composed of nanorods oriented normal to the films in which each nanorod maintains single crystalline though segmented by the horizontal interfaces between each of the two neighboring layers, suggesting nearly perfect epitaxy during multilayer growth. The multidomain state is found in three-/four-layer PZ thin films while the one-/two-layer PZ films always present a monodomain state. Meanwhile, incommensurate phases with different modulation periods have been observed in the four-layer PZ films. By comparing the as-observed structural features with the measured electrical properties of different films, it seems that microstructural evolution with the film thickness should not be negligible in evaluating the structure–property relation of PZ-based thin films. [ABSTRACT FROM AUTHOR]

We show that secondary electrons in a scanning electron microscope can provide important information about spatial dopant distribution in p-i-n GaN structures, with the highest contrast observed for a primary electron beam accelerating voltage in the range of 1 to 2 kV. The current through the specimen is used to determine the total backscattered and secondary electron yield. We establish a correlation between the secondary electron emission intensity and the doping characteristics of the material. The secondary electron emission intensity was found to be highest for p-type GaN, intermediate for n-type GaN, and lowest for undoped GaN. Specimen currents are found to have a strong correlation with the Mg concentration in p-GaN films. The contrast associated with dopants is shown to depend on experimental parameters such as primary electron beam voltage, total electron beam exposure, and specimen surface history. This technique can serve as a powerful tool for the development and characterization of thin films for GaN power electronics. [ABSTRACT FROM AUTHOR]

Taking advantage of electron diffraction based measurements, in a scanning electron microscope, can deliver non-destructive and quantitative information on extended defects in semiconductor thin films. In this work, we have studied a (11-22) semi-polar GaN thin film overgrown on regularly arrayed GaN micro-rod array templates grown by metal organic vapour phase epitaxy. We were able to optimise the diffraction conditions to image and quantify basal plane stacking faults (BSFs) and threading dislocations (TDs) using electron channelling contrast imaging (ECCI). Clusters of BSFs and TDs were observed with the same periodicity as the underlying micro-rod array template. The average BSF and TD densities were estimated to be ≈4 × 104 cm−1 and ≈5 × 108 cm−2, respectively. The contrast seen for BSFs in ECCI is similar to that observed for plan-view transmission electron microscopy images, with the only difference being the former acquiring the backscattered electrons and the latter collecting the transmitted electrons. Our present work shows the capability of ECCI for quantifying extended defects in semi-polar nitrides and represents a real step forward for optimising the growth conditions in these materials. [ABSTRACT FROM AUTHOR]

The electronic spins of rare-earth materials are attractive candidates for spin qubits and quantum memories. To access individual spins, tuning of the g-factor is desirable. Here, we report on local strain-dependent g-factors of the 5D0–7F2 transitions of Eu3+ centers in GaN:Eu thin films. We have found a clear correlation between the effective g-factor and the emission energy shift induced by the local strain. The combination of micro-photoluminescence and scanning electron microscope/electron backscattering diffraction measurements has revealed that the compressive strain of 0.2%–0.4%, relative to a surrounding reference point, induces an energy shift of about 3 meV. The strain decreases the g-factor of the emission at 1.991 eV from 2.5 to 1.5, while the strain increases the g-factor of the emission at 1.994 eV from 1.1 to 1.7. The result suggests that the g-factor can be tuned by the local strain. On the basis of the strain-induced energy shift and the g-factor, we have identified the optical sites. The 5D0–7F2 transitions observed in this study consist of three optical sites with C3v symmetry and one site with C1h symmetry. [ABSTRACT FROM AUTHOR]

Thin films of silver were deposited on nonalkali glass substrates at substrate temperatures ranging from room temperature (28 °C) to 150, 200, 300, 400, and 500 °C at discharge pressures of 0.40, 1.20, and 2.00 Pa using direct current magnetron sputtering. On the basis of the measured cross-sectional and surface morphologies, crystallographic structures, and film properties, I discuss the dependence of the film structure and properties on the substrate temperature. The x-ray diffraction measurements showed that the <111> orientation was preferred for all deposition conditions. Scanning electron microscope observations revealed a microstructure of convex-shaped fine grains for a substrate at room temperature, while laterally growing, mound-shaped grains with flat-topped surfaces appeared at substrate temperatures of 400 and 500 °C. Atomic force microscopy also showed an increase in the lateral size and height of the mound-shaped structures with increasing substrate temperature. The lateral grain size evaluated from the areal particle density obtained from atomic force microscopy increased significantly with increasing substrate temperature, reaching 600–800 nm at a substrate temperature of 500 °C. The film stress also changed from compressive to tensile with increasing substrate temperature. The relative density, defined as the ratio of the deposited amount-of-substance to the physical-thickness, decreased significantly with increasing substrate temperature and, at a substrate temperature of 500 °C, was approximately 0.6 times as large as that obtained for thin films deposited at room temperature. The high surface diffusivity of the Ag adatoms induces the growth of laterally growing, mound-shaped grains. Besides, the energy accumulated in the thin films during sputter deposition induces the void formation to increase the efficiency of energy release in the form of heat. [ABSTRACT FROM AUTHOR]

In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90 K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100 F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT. [ABSTRACT FROM AUTHOR]

Thin films of polycrystalline gallium antimonide (GaSb) were grown on widely available mica substrates using the physical vapor deposition method. The as-grown films contain grains of nano-scale with regular symmetries, as identified by x-ray diffraction and scanning electron microscope analysis. Two-terminal devices with coplanar electrodes were fabricated from the polycrystalline GaSb films; thus, the time dependent photoresponse property of the films was investigated by measuring the current density–voltage characteristics of devices. A significant photoresponse of the device was revealed by the linear dependence of the applied bias. Additionally, the transient behavior of the GaSb thin films was used to optimize growth temperatures of the films. This study shows that polycrystalline GaSb thin films on mica at 500 °C are suitable for high photoresponse and low noise IR photodetectors, thus proving to be a low cost solution for IR photodetectors. [ABSTRACT FROM AUTHOR]

The SnO2:F transparent conductive oxide (TCO) layers with submicron-size textured structures have been characterized using spectroscopic ellipsometry (SE). By applying the Drude model to the SE analysis, the optical carrier concentration, mobility, and sheet resistance of the textured SnO2:F layers have been estimated, in addition to the detailed layered structures. The excellent agreement has been observed between the results obtained from SE and other characterization techniques including scanning electron microscope, atomic force microscope, and Hall measurements, confirming that SE is a reliable measurement technique even for the textured structures. Nevertheless, the electron mobility obtained from SE is lower than that deduced electrically from the Hall measurement, although the carrier concentrations estimated from these techniques are quite similar. From the SE analysis, the optical constants of the textured SnO2:F layers have been extracted, and the free carrier absorption in the SnO2:F layers increases drastically with decreasing optical mobility. The SE technique developed in this study can be applied further to perform the nondestructive mapping characterization of large-area TCO textures incorporated into thin-film solar cell modules. [ABSTRACT FROM AUTHOR]

The crystal structure and surface/interface morphology of zinc-octaethylporphyrin [Zn(OEP)] films deposited on an indium tin oxide (ITO) substrate spin coated with 3,4- polyethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) have been investigated using x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. XRD results indicated that there are two kinds of grains with their sizes of approximately 20 nm that is independent of film thickness and substrate temperature. One has a diffraction plane with an interplanar distance of 1.12 nm and with its orientation parallel to the substrate, whereas the other has a diffraction plane with an interplanar distance of 1.24 nm and with that inclined mainly by 60° to the substrate. The abundant ratio of the two grains was controlled to some extent by varying film thickness and substrate temperature. Cross-sectional SEM images showed that a part of Zn(OEP) molecules are incorporated into PEDOT:PSS for its film thickness smaller than 130 nm, while that Zn(OEP) whiskers begin to grow for its film thickness exceeding 130 nm. [ABSTRACT FROM AUTHOR]

Structural and surface characterizations of the ZnO:Al nanostructured films were achieved by means of x-ray diffraction, scanning electron microscope, atomic force microscope, and nanoindentation measurements. The films exhibited hydrophobic behavior with contact angles of about 133.2°–142.7°, and a decrease in the hardness and Young’s modulus with decreasing indentation depths. Buckling behavior took place during the indentation process, and the fracture strength of the films was also investigated. The results show that the phase transformation from zinc blende to wurtzite structure. Also, it should be correlated with belongs to chairtype Peierls distortion with up to 38° tilting (001) rock-salt structure along the [formula] plane and followed tilting along the [formula] plane by about 32° for a fair match with [formula] Zn. A nanogenerator with ZnO nanorods was then fabricated to define its piezoelectric characteristics. The power density per unit substrate area is about 18.3 μW/mm2. [ABSTRACT FROM AUTHOR]

Pure Ag films were deposited on SiO2/Si with and without introduction of W0.7Ti0.3 barrier layers. The films were annealed in vacuum for 1 h at temperatures up to 650 °C. X-ray diffraction pole figure analysis was used to investigate the texture information in as-deposited and annealed films. After annealing, the {111} texture in Ag films increased; however, the degree of increase was significantly higher in Ag/W–Ti/SiO2. In Ag/SiO2 structures, the {200} texture also increased. In Ag/W–Ti/SiO2 structures, no significant increase in {200} texture was observed; however, {111} twin related {511} texture evolved. In as-deposited samples, {111} pole figure revealed that {111} absolute intensity was higher in Ag/SiO2 than in Ag/W–Ti/SiO2. After annealing, Ag {111} intensity was always higher in Ag/W–Ti/SiO2. Sources for the texture evolution were discussed in detail. Field emission scanning electron microscope showed the presence of twins and abnormal grain growth. After annealing at 650 °C, both the roughness and resistivity of Ag increased significantly. [ABSTRACT FROM AUTHOR]

The electronic and structural properties of copper phthalocyanine deposited onto multiwalled carbon nanotubes were studied as a function of the deposition thickness. The valence band and core level spectra were investigated using photoemission spectroscopy. A shift of the organic highest occupied molecular level toward the Fermi level was observed for very thin film, together with a small shift of the nitrogen and copper core level peak positions. Scanning electron microscope images showed the formation of small particles around the nanotubes, forming a thin overlayer decorating the nanotube walls. An x-ray diffraction analysis reported that these particles present both the α and β crystalline phases. [ABSTRACT FROM AUTHOR]

Ferroelectric Cr-doped BiFeO3 (BFCr) thin films having a rhombohedrally distorted simple perovskite structure were fabricated on the p-type Si (100) substrate by the chemical solution deposition technique. The microstructures and the surface morphologies of BFCr thin films on the p-type Si (100) annealed at 550 °C for 30 min in nitrogen atmosphere were examined by an x-ray diffractometer and a scanning electron microscope, respectively. The capacitance-voltage (C-V) curves for BFCr thin film as the clockwise ferroelectric hysteresis loop were observed. Furthermore, the C-V characteristics for the metal-ferroelectrics-semiconductor structured BFCr thin films were measured as functions of the voltage and the frequency. From these results, the fixed charge density Nfc was calculated as 5.3×1011 cm-2. The leakage current characteristics of BFCr thin films were also measured by a thermally stimulated current measurement. Using the current-voltage curves, the current conduction mechanism of BFCr thin films on the p-type Si (100) capacitor was found to be dominated by the ferroelectric Schottky emission with a barrier height [lowercase_phi_synonym]B of 0.45±0.02 eV. [ABSTRACT FROM AUTHOR]

The ferroelectric properties and leakage current mechanisms of preferred oriented Bi3.25La0.75Ti3O12 (BLT) thin films deposited on La0.5Sr0.5CoO3 by the polymeric precursor method were investigated. These films showed excellent ferroelectric properties in terms of large remnant polarization (2Pr) of 47.6 μC/cm2 and (2Ec) of 55 kV/cm, fatigue-free characteristics up to 1010 switching cycles, and a current density of 0.7 μA/cm2 at 10 kV/cm. X-ray diffraction and scanning electron microscope investigations indicate that the deposited films exhibit a dense, well-crystallized microstructure having random orientations and with a rather smooth surface morphology. The improved ferroelectric and leakage current characteristics can be ascribed to the platelike grains of the BLT films, which make the domain walls easier to be switched under external field. [ABSTRACT FROM AUTHOR]

The ferroelectric properties and leakage current mechanisms of polycrystalline SrBi2(V0.1Nb0.9)2O9(SBVN) thin films, which were deposited on Pt/SiO2/n-Si substrate by rf-magnetron sputtering and then annealed at 700°C for 60 min in air, were investigated. These SBVN films showed excellent ferroelectric properties in terms of a large remnant polarization (2Pr) of ∼25 μC/cm2 (2Ec∼200 kV/cm), fatigue free characteristics up to >=108 switching cycles and a low current density of 10-8 A/cm2 at 100 kV/cm. X-ray diffraction and scanning electron microscope investigations indicate that the sputtered films exhibit a dense, well crystallized microstructure having random orientations and with a rather smooth surface morphology. The improved ferroelectric and leakage current characteristics obtained at the low processing temperature are attributed to the larger polarizability attained through increased rattling space in the distorted Nb(V)O6 of the perovskite block due to the partial substitution of Nb with smaller V ions. The leakage current density of the SBVN thin films was studied at higher temperatures and the data were fitted with the Schottky and Poole-Frenkel emission models. [ABSTRACT FROM AUTHOR]

We report on the roles of hydrogen dilution on the microstructural and optoelectronic properties of boron-doped nanocrystalline silicon thin films grown by plasma-enhanced chemical vapor deposition on glass substrates, through x-ray diffraction, scanning electron microscope, Raman scattering, optical transmission, temperature-dependent dark conductivity, and elastic recoil detection analysis (ERDA) measurements. The grain size, crystallinity, absorption coefficient, refractive index, and conductivity are found to decrease basically with increasing hydrogen dilution ratio ΔH. The Tauc’s optical band gap is found to increase with ΔH due to the quantum size effect. By the aid of hydrogen ion bombardment effect [J. Appl. Phys. 93, 1262 (2003)] as well as the hydrogen-induced annealing effect, the clear increase of hydrogen content with ΔH and the different hydrogen distribution from ERDA help us to elucidate the correlation of hydrogen dilution with the crystallinity and grain size. The argument has been further supported by a simple absorption model and the yielded refractive index and absorption coefficient. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that examined yttrium compound superconducting thin films by using laser-deposition. Information on the structure and morphology of the films; Discussion on the surface morphology and electron channeling patterns of the thin films; Use of scanning electron microscope and atomic force microscope.

Presents a study that investigated thin films of lithium-niobium-oxygen (LiNbO). Morphology of the films; Use of scanning electron microscope and x-ray diffraction; Background on LiNbO; Description of methods for fabricating thin films; Schematic drawing of radio frequency sputtering apparatus.

We report an orientation-controlled FePt thin films grown nonexpitaxially on oxidized Si substrates without using any underlayers. After 700 °C annealing, the FePt single layer with thickness less than 10 nm shows good (001) texture and perpendicular anisotropy. The scanning electron microscope images indicate that these films are composed of isolated islands. For the films thicker than 20 nm, the films become continuous and (111) orientation appears. The transition of film texture relates to the change of morphology of the films. Finally, a theoretical mode based on minimizing surface energy is proposed to explain the texture variation in the films. [ABSTRACT FROM AUTHOR]

In this paper, the authors introduced a novel method for the fabrication of microdevices on freestanding Si3N4 thin-film windows with a single-side mask aligner. A thin-film microdevice located on the front surface of such a freestanding window was demonstrated, where the backside of Si wafer was performed with KOH wet etching. The results showed that an alignment error could be controlled in condition less than 20 lm. By using the freestanding device, a weak change in local temperature under an e-beam in a scanning electron microscope (FEI QUANTA 600F) was detected with better sensitivity. [ABSTRACT FROM AUTHOR]

Presents a study that calculated energy deposition in thin films using electron transport theory. Transport equation in the geometry of scanning electron microscope; Diagram for the specimen and coordinate system; Behavior of amorphous carbon films at very low energies.

Studies the overwrite characteristics of terbium compound thin films using magnetic field modulation using scanning laser microscope. Details on the scanning laser microscope used in the study; Procedure of the experiment; Discussion on the results of the study.

Electrical properties of a ZnO microwire grown by carbo-thermal evaporation, a ZnO thin film grown by pulsed-laser deposition and a hydrothermally grown ZnO bulk crystal are compared. Deep defects were investigated by means of deep-level transient spectroscopy. The defect level E3 was observed in all samples investigated. Additionally, a defect labelled T2 that preferentially forms under Zn-rich condition was detected in the microwire, the thin film and the bulk sample. Our results indicate that VZn is likely involved in this defect. [ABSTRACT FROM AUTHOR]

The fabrication of next-generation devices via roll-to-roll (RTR) nanoimprinting has received considerable attention due to the high throughput and resolution associated with the process. In particular, RTR nanoimprinting with ultraviolet (UV)-curable resin is expected to be useful for the fabrication of large-area devices such as nonreflective films, transparent conductive sheets, and organic solar cells. In order to improve the resolution of such devices, the roll mold must be able to produce seamless fine patterns. Generally, a roll mold for nanoimprinting is made by attaching a planar mold replicated from the master mold via a nickel electroforming technique. However, this method produces seams, which reduces the product yield. In order to resolve these issues, the authors have developed a direct writing method using electron beam (EB) lithography on a rotating cylindrical substrate. In this study, the authors examined the potential for fabricating a seamless roll mold using high-resolution inorganic EB resist and the pattern shrink effect from postexposure bake (PEB). The authors used the dip-and-pull method to form the EB resist layer on the roll mold substrate (32 mm diameter, made of brass). The cleaned roll mold was dipped in the inorganic EB resist and then pulled out at a constant speed. The resulting sample was cured at 300 °C for 1 h. Next, the sample was mounted on rotating equipment and placed in a scanning electron microscope (SEM) equipped with an EB writing system, and the roll substrate was exposed to 10 kV EB while rotating at a constant speed. The revolution speed was set to ten turns per line pattern. Subsequently, PEB was carried out at 200 °C for 10 min in air. After the sample was cooled to room temperature, the EB-exposed area of the EB resist layer was developed using buffered HF. The obtained pattern on the roll mold was examined with the same SEM used for writing. Finally, RTR nanoimprinting using the obtained roll mold was carried out using UV-photocurable resin. At that time, the sample was coated with an antisticking layer of fluorinated silane coupling agent. As a result, a seamless line pattern 190 nm wide was obtained on a polyethylene terephthalate film over a length of 10 cm. [ABSTRACT FROM AUTHOR]

An electrostatic force microscope system in a scanning electron microscope specimen chamber was developed to measure the surface potential of an insulator film on a conductive substrate irradiated by an electron beam. As the accelerating voltage varies with the constant beam current, the surface charges positively if the voltage is lower than 1 kV or higher than 3 kV but negatively if the voltage is between 1.1 and 2.7 kV. This positive-negative-positive potential alternation is explained by the relationship between the electron range and the film thickness, and verified by the Monte Carlo simulation of electron trajectories. By selecting the acceleration voltage as 30 kV to show less potential variation with time, the spatial potential distribution at the specimen surface is obtained, and a negative dip is observed around 50 μm from the edge of the irradiated area. The authors find that the depth of the dip increases with an increase in the electron dose, and the negative potential distribution spreads over 300 μm is obtained, which is almost 10 times larger than the primary electron range in the specimen. The characteristic variation in the distribution agrees with a hypothetically derived charge distribution obtained in a different experiment. [ABSTRACT FROM AUTHOR]

A UHV instrument is presented for in situ fabrication of nanostructures and in situ investigation of their magnetoresistance. Nanostructures of diverse shape and size are created from thin films utilizing a focused ion beam. The magnetic nanostructures are contacted via a micromanipulator, which makes it possible to address the individual structures. The system is additionally equipped with a scanning electron microscope column, which is used for damage-free navigation and control of the structuring and contacting. First magnetoresistance measurements of structures carved into a Permalloy film demonstrate the high sensitivity and the flexibility of the new setup. [ABSTRACT FROM AUTHOR]

The chemical and electronic surface structure of Cu2ZnSnS4 thin-film solar cell absorbers has been investigated by direct and inverse photoemission. Particular emphasis was placed on the impact of KCN etching, which significantly alters the surface composition and is best explained by a preferred etching of Cu and, to a lesser degree, Sn. As a consequence the surface band gap increased from (1.53 ± 0.15) eV, which agrees with optically derived bulk band gap values, to (1.91 ± 0.15) eV. [ABSTRACT FROM AUTHOR]

Application of the CuInSe2-based thin film for a near-infrared (NIR) photodetector (PD) has been demonstrated. The Cu(In,Al)Se2 (CIAS) was used as an absorption layer for NIR PD with comb-structured Al electrodes. X-ray diffraction spectrum and scanning electron microscope (SEM) micrographs show that the CIAS film is a single phased polycrystalline film with smooth surface and super large (2-5 μm) grains. Low temperature photoluminescence analysis indicates that the CIAS has a strong NIR excitation emission peak. The CIAS PDs are highly sensitive to the NIR spectrum with cut-off frequency near 790 nm and demonstrate four-orders of magnitude in photocurrent amplification. [ABSTRACT FROM AUTHOR]

Cu2ZnSnSe4 thin films grown by coevaporation are investigated in a wide temperature range and for different Se partial pressures during growth. At temperatures higher than 350 °C Sn is re-evaporating as SnSe from the surface whereas Zn is lost at temperatures higher than 430 °C. Moreover the Se partial pressure dramatically changes the Zn and Sn concentrations in the resulting film. Interrupted processes at 380 °C show that single-stage coevaporation intrinsically induces a secondary phase at the substrate/film interface. [ABSTRACT FROM AUTHOR]

This paper describes the sputter deposition and characterization of nickel titanium (NiTi) thin film shape memory alloy onto the surface of an optical fiber Bragg grating. The NiTi coating uniformity, crystallinity, and transformation temperatures are measured using scanning electron microscope, x-ray diffraction, and differential scanning calorimeter, respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e., a modified multiferroic material. [ABSTRACT FROM AUTHOR]

Mn1.56Co0.96Ni0.48O4 films with spinel structure were prepared on Al2O3 substrate by chemical solution deposition method. The microstructure of the films was studied by atomic force microscope and field-emission scanning electron microscope. The current-voltage characteristics showed Ohmic conductivity in the temperature range of 245–295 K. The conduction was described by a variable range hopping model for a parabolic density of states. The advantages of high characteristic temperature, as well as high transition temperature (201 K) between ferromagnetic and paramagnetic phases make the Mn1.56Co0.96Ni0.48O4 films very promising for infrared detection, especially for functional devices by integrating magnetic and electronic properties of the materials. [ABSTRACT FROM AUTHOR]

Single crystalline rectangular shape nanorods with an anatase or rutile TiO2 were synthesized by a soft-chemical process. These nanorods were highly dispersed in aqueous solutions and their surfaces have well-defined crystal faces, i.e., anatase (100) and rutile (110) faces. Highly oriented thin films with either an anatase and rutile phase were fabricated by facile spin coating of these colloidal solutions of nanorods without an annealing procedure. The surfaces of these films exhibited highly hydrophilic conversion under white fluorescent light bulb illumination. [ABSTRACT FROM AUTHOR]

The biaxial piezospectroscopic coefficient (i.e., the rate of spectral shift with stress) of the electrostimulated near-band-gap luminescence of gallium nitride (GaN) was determined as Π=-25.8±0.2 meV/GPa. A controlled biaxial stress field was applied on a hexagonal GaN film, epitaxially grown on (0001) sapphire using a ball-on-ring biaxial bending jig, and the spectral shift of the electrostimulated near-band-gap was measured in situ in the scanning electron microscope. This calibration method can be useful to overcome the lack of a bulk crystal of relatively large size for more conventional uniaxial bending calibrations, which has so far hampered the precise determination of the piezospectroscopic coefficient of GaN. The main source of error involved with the present calibration method is represented by the selection of appropriate values for the elastic stiffness constants of both film and substrate. The ball-on-ring calibration method can be generally applied to directly determine the biaxial-stress dependence of selected cathodoluminescence bands of epilayer/substrate materials without requiring separation of the film from the substrate. [ABSTRACT FROM AUTHOR]

Fabrication and characterization of a nanoelectromechanical switching device consisting of a suspended multiwalled carbon nanotube and self-aligned electrodes is reported. The device has a triode structure and is designed so that a suspended carbon nanotube is mechanically switched to one of two self-aligned electrodes by repulsive electrostatic forces between the nanotube and the other self-aligned electrode. Carbon nanotubes are dispersed on an SiO2 coated Si wafer and their locations recorded using a scanning electron microscope mapping process. Contact electrodes and self-aligned deflection electrodes are formed by a process comprising electron beam lithography, metallic thin film deposition, and lift-off. The electrical measurements show well-defined ON and OFF states with change of gate voltage. The measured threshold voltage for electromechanical switching is ∼3.6 V. [ABSTRACT FROM AUTHOR]

The Eu-doped GaN thin films (GaN:Eu) were deposited on the sapphire substrate by means of the rf magnetron sputtering method. The GaN:Eu films were characterized by x-ray diffraction, scanning electron microscope, and photoluminescence (PL). Although as-grown GaN:Eu films (2 mol % Eu in target) exhibited weak broad Eu-related red PL, the annealing in NH3 atmosphere (1000°C for 1 h) led to the remarkable enhancement of Eu-related PL lines. PL spectra of such annealed GaN:Eu films exhibited a series of sharp PL lines characteristic of substitutional Eu3+ ions at Ga sites in the GaN lattice (dominant PL line is at 622 nm for the 5D0-7F2 transition). On the other hand for GaN:Eu films (5 mol % Eu in target), as-grown films are amorphous and exhibited broad Eu3+-related PL lines. The annealing led to the crystallization of the films, the elimination of Eu3+-related PL lines, and the enhancement of the near-band-edge PL. The Eu-luminescent centers are considered to be removed during the crystallization. [ABSTRACT FROM AUTHOR]

Describes the use of a near-field scanning microwave microscope to quantitatively image the dielectric permittivity and tunability of thin film dielectric samples. Microscope's response to dielectric permittivity; Finite-element calculation of the rf electric field near the probe tip; Tunability of the dielectric properties at a fixed point on the sample.

Examines the maskless laser patterning of insulating thin films from salt solutions. Dimensions of the patterned films; Use of scanning electron microscope and electrical probing measurements to confirm the insulating nature of films; Absorption of laser radiation by the substrate.

Presents a technique for poling barium titanate thin films by electron beam irradiation. Use of scanning electron microscope to measure the enhanced second harmonic generation intensity of the materials; Comparison of irradiation with corona poling of the film at room temperature; Effectiveness of the method for nonlinear optical device fabrication.

Applicability of UV nanoimprint based on gas condensation to 45 nm line and space (L/S) patterning using a spin-coat UV curable resin was evaluated. Although high capillary pressure is generated in such fine L/S patterns when UV curable resin liquid comes in contact with the groove surface, the trapped air in those grooves is not completely compressed and results in the formation of bubble defects. Bubbles much larger than the pattern size were generated at the middle of the L/S patterns for a 108 nm thick, UV curable resin film, and incomplete filling may occur on a large area of the L/S patterns for a 19 nm thick film. Since nearly bubble-free L/S patterns have been fabricated for 48 nm thick, UV curable resin film, it might be possible to make bubble-free UV nanoimprint by prolonging the imprinting time. On the contrary, when UV nanoimprint was carried out in pentafluoropropane (PFP), no bubbles were created for all thicknesses of the UV curable resin films. Uniformity of residual layer looked quite good judging from the color uniformity of the area around the L/S patterns. It was found, from the residual layer measurement by a reflective thickness monitor, that bubble-free UV nanoimprint was carried out with a residual layer thickness of 15.2 nm. UV nanoimprinted samples were inspected with a scanning electron microscope and it was verified that UV nanoimprint using PFP is viable for the fabrication 45 nm L/S patterns. [ABSTRACT FROM AUTHOR]