Ghassem Kavei

Thin films constituted by nano-size TiO2 particles were prepared by spray pyrolysis aerosol. The aerosol was generated ultrasonically, of titanium butoxide deposited on the substrate at 250° and 375°C temperature. As-deposited films were annealed at 600°, 700°, 800°, 900° and 1000°C, in atmospheric conditions. Raman and glancing angle X-ray diffrac...

(Bi0·25Sb0·75)2Te3 thermoelectric material is a well known p type of compound that has higher figure of merit than other stoichiometries. The crystal of this compound was prepared, pulverized in a particle size ratio of 64% with a mesh of 80 (200 μm2) and 36% with a mesh of 60 (250 μm2). The powder was sintered in a heat up to 350–500°C under press...

(Bi2Te3)x (Sb2Te3)1−x solid solutions with x = 0:2, 0.25 and 0.3 − p type thermoelectric compounds with an excess of Tellurium dopant up to 4 wt% were crystallized. By increasing the Bi2Te3 content in the Bi-Sb-Te system, the hole concentration decreased and in consequence caused an optimum Seebeck coefficient and a decrease in electrical conductiv...

(Bi2Te3)0.96(Bi2Se3)0.04 crystal, which is an n-type thermoelectric semiconductor, has many applications in thermoelectric cooling systems. Single crystal of this composition was grown by Traveling Heater Method. A sensible gradient in thermoelectric power factor was observed in the first quarter length of the prepared crystalline ingot. Characteri...

Indium tin oxide (ITO) was deposited on a glass (Soda Lime glass) by RF sputtering system at different sputtering gas (Argon/oxygen 90/10%) pressures (20–34 mTorr) at room temperature. The sputtering rate was depended on sputtering gas pressure. The optimum sputtering gas pressure of 27 mTorr provides homogenous and most favorable rate of depositio...

Thermal conductivity is an important characteristic of materials in particular semi-conductors and ceramics. Since it varies within a wide range and is measured in a variety of methods, no commercial device has, so far, been established to measure thermal conductivity. Hence, it sounds necessary to develop a device to meet all needs of scholars in...

P-type Sb2−x Bi x Te3 crystals with various chemical compositions (x = 0.40, 0.44, 0.47, 0.50, 0.53, 0.56 and 0.60) were fabricated by zone melting method. Transmission electron microscopy and energy dispersive X-ray microanalysis were performed to characterize the evolutions of defects on the sites of Bi, Te and Sb atoms in the lattice. Study o...

Indium tin oxide was deposited on a glass (soda lime glass) by radiofrequency sputtering system at different sputtering gas (argon/oxygen 90/10%) pressures (20-34 mTorr) at room temperature. The sputtering rate was affected by the sputtering gas pressure. The optimum sputtering gas pressure was found to be 27 mTorr. The samples at different thickne...

Empirical studies on the fabrication of thermoelectric element Bi2Te2.88Se0.12 undoped and doped by 0.08 wt.% CdCl2 or CdBr2 have been carried out. Zone melting method was employed to crystallize the solid solutions of the compounds. Structural characteristics of the grown crystals were examined by XRD technique. Measurements of thermoelectric para...

The effect of etching time scale of glass surface on its statistical properties has been studied using atomic force microscopy technique. We have characterized the complexity of the height fluctuation of a etched surface by the stochastic parameters such as intermittency exponents, roughness, roughness exponents, drift and diffusion coefficients an...

Indium tin oxide (ITO) thin films were deposited on glass substrates by RF sputtering system at different sputtering pressure (SP) (20–34 mTorr) and room temperature. The sputtering pressure effects on the deposition rate, electro-optical and structural properties of the as-deposited films were systematically investigated. The optimum sputtering pr...

In the present study, p-type (Bi2Te3) x(Sb2Te3)1-x crystals with various chemical compositions (x = 0-2, 0-22, 0-235, 0-25, 0-265, 0-28 and 0-3) were fabricated through the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ), thermal conductivity (Κ) and Hall constants, were measured at roo...

This research investigates the effect of ion implantation dosage level and further thermal treatment on the physical characteristics of chromium coatings on Si(1 1 1) substrates. Chromium films had been exposed to nitrogen ion fluencies of 1 × 1017, 3 × 1017, 6 × 1017 and 10 × 1017 N+ cm−2 with a 15 keV energy level. Obtained samples had been heat...

We have investigated the effect of bias voltage on sheet resistance, surface roughness and surface coverage of Co/NiOx magnetic bilayer. In addition, interface topography and corrosion resistance of the Ta/Co/Cu/Co/NiOx/Si(1 0 0) system have been studied for Co layers deposited at an optimum bias voltage. Atomic force microscopy (AFM) and four poin...

In this investigation, we have fabricated Co/Cu/Co/NiO/Si(100) magnetic multilayer structure using a combinative sputtering-evaporation technique. Nickel Oxide with a thickness of about 30 nm was deposited on Si(100) substrate by thermal evaporation method. Following the oxide deposition, cobalt and copper films with a thickness of about 3 and 2 nm...

We investigate the Markov property of rough surfaces. Using stochastic analysis, we characterize the complexity of the surface roughness by means of a Fokker-Planck or Langevin equation. The obtained Langevin equation enables us to regenerate surfaces with similar statistical properties compared with the observed morphology by atomic force microsco...

The spatial scaling law and intermittency of the $V_2 O_5$ surface roughness by atomic force microscopy has been investigated. The intermittency of the height fluctuations has been checked by two different methods, first, by measuring scaling exponent of q-th moment of height-difference fluctuations i.e. $C_q = < |h(x_1) - h(x_2)|^{q} >$ and the se...

The spatial scaling law and intermittency of the V2O5 surface roughness has been investigated by atomic force microscopy. The intermittency of the height fluctuations has been checked by two different methods, first, by measuring the scaling exponent of the q th moment of height-difference fluctuations i.e. Cq = |h(x1) − h(x2)|q , and second, by de...

The ejected-electron spectrum of potassium vapour has been observed at 50 degrees and 75 degrees with respect to an incident-electron beam of 30 to 400 eV incident energy. Ejected-electron energies are in the range 4 to 21.5 eV. A total of 84 autoionising states of K I are reported, of which 49 have been identified by comparison with ultraviolet ab...