Narrow Results

Magnetic susceptibility of the Co–Ni suck-cast plates underwent an abrupt change at 32 at% Ni due to phase transformation. Strain value of Co-32 at% Ni cast plate increased from 54 to 850 με as temperature decreased to 150 K. Phase formation of thin film is dependent upon deposition condition.

X-ray photoelectron spectroscopy (XPS) analysis of amorphous carbon (a-C)-based nanocomposite films has been carried out. Four bonding types of carbon are revealed from the C 1s spectra: C–Csp² and sp³ bonding, C–O and C–Ti bonding. With the introduction of Ti and Al into the a-C matrix, the carbon sp³/sp² ratio decreases significantly. XPS results also confirm that the Al doped in the film basically exists as an elemental Al in the a-C matrix, and the titanium is mostly bonded with carbon to form nc-TiC.

Gold nanoparticles (AuNP)-embedded indium oxide and indium tin oxide thin films were prepared by DC and DC magnetron reactive co-sputtering techniques. The concentration and size distribution of AuNP were changed by deposition conditions. The nanoparticles-embedded films were characterized by X-ray diffraction, transmission electron microscopy, and optical spectrophotometry. The X-ray diffraction data showed the polycrystalline nature of indium oxide and indium tin oxide along with the Au (111) peak confirming the presence of elemental AuNP in the matrices. The transmission electron microscope studies revealed that AuNP are distributed in the matrices in different shapes and sizes with the average sizes as 40 nm and 10 nm, respectively for DC-sputtered and DC magnetron-sputtered films. The optical absorbance measurements showed the SPR peak due to AuNP to be around 600 nm. The position and intensity of the SPR peak could be tuned from 650 to 570 nm by changing the concentration of AuNP and annealing the films in oxygen and Ar for different durations.

We have grown metal catalyst free, straight Si nanowires (NWs) with high aspect ratio of about 130 on Si(100) substrate using radio frequency magnetron sputtering. Thin Si seed layer on thermally oxidized substrate was used for catalyst-free growth. Then Si deposition was done on that substrate using sputtering technique followed by heat treatment at different temperatures (900°C–1100°C). Sample heated at 1000°C results in straight, long, and uniform cylindrical shaped Si NWs with diameter 62–74 nm and length up to 8 μm, whereas sample heated above 1000°C transformed toward nanorods with larger diameter. However, no significant growth of Si NWs took place at 900°C. Sputter deposition technique provides an alternate fabrication route for Si NW synthesis. For comparison, we have also grown Au catalyst assisted Si NWs on Si(100) substrate by similar process. These nanowires also show similar morphology with diameter 48–65 nm and aspect ratio about 165. Growth mechanism and effect of growth temperatures on the structure and morphology of Si NWs are discussed.

Titanium oxide films were deposited on Si and quartz substrates by RF magnetron sputtering of titanium target under various oxygen partial pressures. The films were annealed in air at different temperatures and the influence of annealing temperature on the structural and optical properties was studied. The XPS studies revealed that the films formed at oxygen partial pressure of 2 × 10^-2 Pa were nearly stoichiometric. The as-deposited films were amorphous, the films annealed at 573 K were anatase, while those annealed at 973 K were mixed anatase and rutile phases of TiO₂. The as-deposited films showed an optical bandgap of 3.32 eV while those annealed at 973 K was 3.19 eV.

Undoped and phosphorus doped nanocrystalline nickel oxide thin films have been synthesized on silicon and glass substrates by RF magnetron sputtering technique in pure Ar atmosphere. Proper phase formation was confirmed by X-ray diffraction analysis. Energy band gaps were determined using UV-Vis spectra. Formation of NiO nanoparticle of dimension ~15 nm was confirmed using HRTEM. Doping of phosphorus as an impurity was confirmed from EDX spectra and XPS studies. Spectroscopic ellipsometric studies were performed on such films and the spectra were analyzed with a suitable model. Optical constants were determined and refractive indices were found to increase with increase of phosphorus doping percentages.

This paper presents the growth of bismuth ferrite (Bi₂Fe₄O₉) thin film by radio frequency magnetron reactive sputtering on p-Si (100) substrate and the characterization of the grown thin film. The deposited thin film is characterized by X-ray diffraction (XRD), field emission scanning electron micrograph (FESEM), energy dispersive X-ray analysis (EDAX), dielectric measurements and vibrating sample magnetometer (VSM) analysis. The XRD study reveals the orthorhombic structure of the crystallites and the particle size is calculated as 45 nm. The FESEM result confirms that the film has smooth surface and uniform distribution of nanoclusters. The percentage of chemical compositions of the film is confirmed by EDAX measurement. The dielectric behavior of the film is examined in terms of the dielectric constant and the dielectric loss as a function of frequency. The magnetic behavior of the film is measured using VSM with the applied magnetic field of about 1 Tesla and the result shows the ferromagnetic behavior of the sample at room temperature.

Zinc oxide (ZnO) thin films have been deposited onto thoroughly cleaned stainless steel (AISI SS 304) substrates by reactive direct current (dc) magnetron sputtering and the films were doped with silver (Ag). The prepared thin films were analyzed using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) to investigate the structural and morphological properties. The thickness values of the films were in the range of 194 to 256nm. XRD results revealed that the films were crystalline with preferred (002) orientation. Grain size values of pure ZnO films were found to be 19.82–23.72nm. On introducing Ag into ZnO film, the micro-structural properties varied. Adhesion test was carried out with Staphylococcus aureus (S. aureus) in order to know the adherence property of the deposited films. Colony formation units (CFU) were counted manually and bacterial adhesion inhibition (BAI) was calculated. We observed a decrease in the CFU on doping Ag in the ZnO films. BAI of the film deposited at – 100 V substrate bias was found to be increased on Ag doping from 69 to 88%.

Thin film memristor behavior depends on the choice of top and bottom electrode material and metal oxide layer. In the present work, the influence of the top and bottom electrode layers on the electric field-induced resistance switching phenomena of TiO₂-based MIM was studied. Au/TiO₂/NiCr and NiCr/TiO₂/Au structures were fabricated by depositing TiO₂ active layer by reactive dc magnetron sputtering technique between thermally evaporated NiCr and Au electrodes. TiO₂ layer was sputtered with a cathode power of 150W keeping the other deposition parameters constant. TiO₂ films were analyzed by X-ray diffractometer, field emission scanning electron microscopy and UV–Visible spectrophotometer to investigate their structural, morphological and optical behavior. Structural studies of the films reveal that the samples were amorphous. And the $I$–$V$ analysis for the fabricated MIM structure was analyzed.

The present work deals with NiO/Si₃N₄ layers formed by depositing nickel oxide (NiO) thin films over silicon nitrate (Si₃N${}_4)$ thin films. NiO films were coated on Si₃N₄-coated Si substrate using magnetron sputtering method by changing duration of coating time and were analyzed using X-ray diffractometer, field emission-scanning electron microscopy, UV–Vis spectrophotometer and four-point probe method to study the influence of thickness on physical properties. Crystallinity of the deposited films increases with increase in thickness. All films exhibited spherical-like structure, and with increase in deposition time, grains are coalesced to form smooth surface morphology. The optical bandgap of NiO films was found to decrease from 3.31eV to 3.22eV with upsurge in the thickness. The film deposited for 30min exhibits temperature coefficient resistance of $-$1.77%/${}^{\circ }$C as measured at 80${}^{\circ }$C.

Zinc oxide (ZnO) thin films have been synthesized by thermally oxidizing the direct current magnetron sputtered zinc (Zn) films at 500${}^{\circ }$C for different annealing time periods (3–5h) in ambient air. Influence of annealing time on the structural, morphological, optical and electrical properties of ZnO films was studied using X-ray diffractometer, field emission-scanning electron microscopy (FE-SEM), UV–Vis spectrophotometer and two-probe method, respectively. ZnO films exhibited hexagonal crystal structure with (1 0 1) as preferential orientation plane, and the crystallite size of the films increased from 30nm to 83nm on increasing the annealing time. Pebble-like surface morphology was observed from the FE-SEM micrographs. Optical band gap of the films varied between 3eV and 3.5eV for different annealing times. Electrical resistance of the ZnO films was decreased with increase in the annealing time, which is due to the improvement in the crystallinity.

Zinc oxide (ZnO) films have been sputter coated over glass substrates at different cathode powers. Influence of cathode power on physical characteristics of ZnO samples was analyzed using X-ray diffractometer (XRD), field emission-scanning electron microscopy (FE-SEM), UV-Visible spectrophotometer and four-point probe (FPP) method. XRD patterns exhibited $c$-axis-oriented ZnO and enhanced crystallinity with increase in cathode power due to the increase in adatom mobility. Uniformly arranged spherical grains were observed from FE-SEM images. The grain size increased from 25 to 40nm with increase in power. All samples exhibited high electrical resistance (G$\mathrm{\Omega }$) which is compatible for piezoelectric application.

Metal nanostructures and noble metal-based nanostructures, in particular, exhibit plasmonic resonance in the visible region. The resonance absorption can be tuned by varying the size of nanoparticle and the external matrix in which the plasmonic materials are embedded. Mie’s theory has been used to demonstrate the shift in the plasmonic resonance in gold nanoparticles embedded in different dielectric media. Two model systems, viz. Au–ZnO and Au–Al₂O₃, prepared by sputtering on quartz substrates were used to study the optical absorption. The plasmonic peaks were observed to be red shifted in Au–Al₂O₃ and Au–ZnO, as is also supported by Mie formalism. The dielectric constant of the external matrix viz., Al₂O₃ and ZnO, estimated using the experimental and the Mie simulations are 3.05 and 1.83, respectively.