A. Sivasankar Reddy

Preparation and characterization of Nickel Oxide thin films by direct current reactive magnetron sputtering at different substrate temperatures

The influence of substrate temperature on the properties NiO films, prepared by dc reactive magnetron sputtering technique, is studied by various characterization methods. X-ray diffraction studies revealed that the crystal structure is highly influenced by the substrate temperature. The optical results indicated that the optical transmittance and band gap of the films increased with the increase of substrate temperature up to 523 K. The optical band gap of NiO films decreases from 3.82 to 3.70 eV with the increase of substrate temperature from 523 to 723 K. The electrical resistivity decreased with the increase of substrate temperature from 303 to 723 K, whereas carrier concentration and Hall mobility increased with increasing the substrate temperature.

Influence of substrate temperature on the electrical, morphological and structural properties of electron beam evaporated LBMO thin films

La0.7Ba0.3MnO3 (LBMO) thin films were deposited on Si substrates at various substrate temperatures (Ts) ranging from 823 K to 1023 K using electron beam evaporation (EBE), and studied the structural, composition and electrical properties of the films as a function of deposition temperature were studied. X-ray diffraction (XRD) studies revealed the epitaxial growth in the films. The surface morphology of the films were characterized by atomic force microscopy (AFM). The elemental composition analysis investigated by energy dispersive spectroscopy (EDS) confirmed the stoichiometry. The films deposited at higher substrate temperatures (1023 K), showed lower resistivity with a higher temperature coefficient of resistance (TCR). A TCR of 4.09%/K obtained in the present investigation is suitable for bolometric applications near to the room temperature.

Analysis of the Effect of Temparature on the Resistivity of Nanocrystalline La0.7 Ba0.3MnO3 Powders

A Systematic investigation on structural, electrical, microstructure and compositions properties of La0.7Ba0.3MnO3 powder, prepared by a standard solid state reaction method, has been undertaken. The XRD pattern showed that the as prepared LBMO material was in single-phase rhombohedral structure. The electrical properties of as grown powders were carried out using standard four probe technique. The influence of dc biasing current on temperature dependence of resistance of La0.7Ba0.3MnO3 powder was reported. From electrical data it was observed that the electrical resistance decreased with bias current indicating the alignment of spins and increase in spin stiffness coefficient and decreasing the resistance at metal-insulator transition temperature (TMI). The surface morphology of the samples was studied by scanning electron microscope. From scanning electron micrographs, granular features were observed with average grain size of ~20nm.

Structural and morphological properties of sputtered NiO thin films at various sputtering pressures

Nickel oxide thin films were successfully deposited on glass substrates at different sputtering pressures in the range of 3 × 10−2 to 5 × 10−2 mbar. It was observed that sputtering pressure influenced the structural and morphological properties. Structural properties were studied with X-ray diffractometer. All the deposited films were polycrystalline and exhibited cubic structure with preferential growth along (220) plane. From morphological studies it was observed that fine and uniform grains with RMS roughness of 9.4 nm were obtained when the films deposited at a sputtering pressure of 4 × 10−2 mbar,. The grain size and the surface roughness decreased at higher sputtering pressures. The surface mobility of the adatoms decreased after series of collisions resulting in the decrease of grain size at high sputtering pressures.

Oxygen Partial Pressure Dependent Properties of Nanocrystalline Nickel Oxide Films

Nickel oxide thin films have been successfully deposited by dc reactive magnetron sputtering technique on glass substrates at different oxygen partial pressures. X-ray diffraction analysis revealed that the preferred orientation changed from (200) to (220) with increasing oxygen partial pressure. Fine grains with RMS roughness of 9.4 nm were observed at an oxygen partial pressure of 6 × 10−4 mbar.

Influence of substrate bias voltage on the properties of sputtered nickel oxide thin films

Nickel oxide (NiO) thin films were deposited on glass substrates at various substrate bias voltages by dc reactive magnetron sputtering technique. The effect of substrate bias voltage on the structural, morphological and compositional properties was systematically investigated by X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) and Energy Dispersive Spectroscopy (EDS) respectively. From XRD studies it was observed that all the deposited films were polycrystalline with preferential growth along (200) reflection. The RMS roughness of the films was increased as substrate bias voltage increased. Energy Dispersive Spectroscopy studies revealed that all the deposited films consists of nickel and oxygen.

Structural, Morphological and Composition Analysis of Nanocrystalline La0.67Ba0.33MnO3 Powder

La0.67Ba0.33MnO3 powders were successfully prepared by a standard solid state reaction method, and systematically investigated the influence of the sintering temperature on the structural, microstructure, composition properties. The XRD pattern showed that the as prepared LBMO material was in single-phase with rhombohedral structure. From the scanning electron micrographs, it was observed that the grain size increased with sintering temperature and the average grain size was ~40nm.The surface roughness was measured by atomic force microscope and the RMS roughness of samples was in the range 48 to 85 nm. The as prepared samples exhibited nearly the same composition of the base material.