Magnetic properties and relaxation of the magnon populations in the super lattice [Fe/GaAs]

In the present work we study the properties of elementary excitations in a magnetic super lattice [Fe/GaAs] which is described in framework of the ferromagnetic Heisenberg system where the exchange and the dipolar interactions, the magneto-crystalline and surface anisotropies are all taking into account. The corresponding Hamiltonian is treated by the Green’s function method. The analytical expressions of the excitation spectrum and the magnetization per spin are obtained when the exchange is present alone. A good adjustment of calculated magnetization with the experimental results is obtained for various magnetic layer thickness . The deduced exchange integrals are in agreement with previous studies. The combined effect of dipolar interactions and surface anisotropy is studied numerically

Preparation And Characterisation Of Zno Thin Films Deposited By SILAR Method

Zinc oxide (ZnO) thin films were grown on glass and copper substrates by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique. ZnO films are obtained by successive immersion of a substrate in an aqueous solution containing: ZnSO4 with different molarities, 6ml/100ml 13.15 M aqueous ammonia solution and in deionised water heated at different temperatures. We studied the structural, morphological and optical properties with the deposition parameters (pH, bath temperature, number of cycles…) The structural, morphological surface and optical properties of the films have been studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-VIS-spectrophotometer. Effects of experimental parameters and heat treatment on the structural and optical properties were discussed. The X-ray diffraction analysis shows that the films are polycrystalline with zincite hexagonal structure with the preferential orientation of (002) plan. The study of surface morphology reveals that deposited ZnO films take many shapes: nanorods, nanoprisms, flower-like, needles, spindles and hexagonal structures. Obtained ZnO films exhibit a high transmittance of 90% in visible band, and optical band gap of 3.27 eV.Zinc oxide (ZnO) thin films were grown on glass and copper substrates by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique. ZnO films are obtained by successive immersion of a substrate in an aqueous solution containing: ZnSO4 with different molarities, 6ml/100ml 13.15 M aqueous ammonia solution and in deionised water heated at different temperatures. We studied the structural, morphological and optical properties with the deposition parameters (pH, bath temperature, number of cycles…) The structural, morphological surface and optical properties of the films have been studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-VIS-spectrophotometer. Effects of experimental parameters and heat treatment on the structural and optical properties were discussed. The X-ray diffraction analysis shows that the films are polycrystalline with zincite hexagonal structure with the preferential orientation of (002) plan. The study of surface morphology reveals that deposited ZnO films take many shapes: nanorods, nanoprisms, flower-like, needles, spindles and hexagonal structures. Obtained ZnO films exhibit a high transmittance of 90% in visible band, and optical band gap of 3.27 eV

Magnetic and non magnetic thickness effect on the exchange integrals in Co/Pt multilayers

In this paper, we report a theoretical study of elementary magnetic excitation properties of Co(tCo)/Pt(tPt) multilayers. We establish the corresponding spin hamiltonian by including exchange interactions, surface anisotropy and dipolar interactions. This hamiltonian is treated by Green’s function method. The calculated magnetization for various values of the magnetic layer thickness (tCo) as well as those of the non-magnetic one (tPt) according to the temperature is in good agreement with the experimentally measured one for these thicknesses and temperature. The deduced exchange integral values are satisfactory in agreement with the values known for 3d transition metals like cobalt

Physical properties of CdSexTe1-x thin films prepared by electrodeposition

The cadmium chalcogenides CdSexTe1-x (0≤x ≤1 ) thin films have been electrodeposited onto ITO coated glass substrates from an acid sulphate solution at 90 °C. The structure, the composition and the morphology have been studied as a function of the x coefficient by XRD, EDAX, optical absorbance and AFM techniques. All deposits have a cubic structure with a preferred orientation along the (111) direction. The composition in the films is found to vary linearly with the composition in the solution. The increase of the amount of tellurium in the CdSexTe1-x films decreases the band gap down to 1.35 eV and increases the lattice constant. The photoelectrochemical studies in a polysulfide electrolyte show that CdSexTe1-x thin films behave as n-type semiconductors.The cadmium chalcogenides CdSexTe1-x (0≤x ≤1 ) thin films have been electrodeposited onto ITO coated glass substrates from an acid sulphate solution at 90 °C. The structure, the composition and the morphology have been studied as a function of the x coefficient by XRD, EDAX, optical absorbance and AFM techniques. All deposits have a cubic structure with a preferred orientation along the (111) direction. The composition in the films is found to vary linearly with the composition in the solution. The increase of the amount of tellurium in the CdSexTe1-x films decreases the band gap down to 1.35 eV and increases the lattice constant. The photoelectrochemical studies in a polysulfide electrolyte show that CdSexTe1-x thin films behave as n-type semiconductors

ONE STEP ELECTRODEPOSITION OF CuInSe2 THIN FILMS

Formation of CuInSe2 (CIS) thin films from aqueous solution containing citrate as complexing agent is reported. The surface morphology and the composition of the deposited films are characterized by scanning electron microscopy (SEM). The texture of the deposits and their compositions are analyzed by X-ray diffraction and transmission electron microscopy (TEM). Annealing of the films at 350°C in flowing argon electrodeposited at potentials in the range [-0.24, -0.4 (V vs Ag/AgCl)] resulted in the formation of alpha-Cu 2 Se (JCPDS 24-1131) and CuSe (JCPDS 6-0427). On the contrary, annealing in the same conditions of the films electrodeposited between -0.4 and -0.6 V vs Ag/AgCl led to the formation of chalcopyrite CuInSe 2 (JCPDS 23-209) with alpha-Cu 2 Se (JCPDS 24-1131) as secondary phase. The formation of CuInSe 2 films with a chalcopyrite structure and good stoichiometry is observed.Formation of CuInSe2 (CIS) thin films from aqueous solution containing citrate as complexing agent is reported. The surface morphology and the composition of the deposited films are characterized by scanning electron microscopy (SEM). The texture of the deposits and their compositions are analyzed by X-ray diffraction and transmission electron microscopy (TEM). Annealing of the films at 350°C in flowing argon electrodeposited at potentials in the range [-0.24, -0.4 (V vs Ag/AgCl)] resulted in the formation of alpha-Cu 2 Se (JCPDS 24-1131) and CuSe (JCPDS 6-0427). On the contrary, annealing in the same conditions of the films electrodeposited between -0.4 and -0.6 V vs Ag/AgCl led to the formation of chalcopyrite CuInSe 2 (JCPDS 23-209) with alpha-Cu 2 Se (JCPDS 24-1131) as secondary phase. The formation of CuInSe 2 films with a chalcopyrite structure and good stoichiometry is observed

Effect of heat treatment with CdCl2 on the electrodeposited CdTe/CdS heterojunction

CdS/CdTe heterojunction was subjected to chemical treatment commonly used in photovoltaic device fabrication to determine the resulting microscopic effect on the morphology and structure. CdS and CdTe thin films were electrodeposited successively onto indium tin oxide (ITO) from aqueous solution. Containing CdCl2 and Na2S2O3 for the deposition of thin film windows, the ITO/CdS resulting substrates was then used for the deposition of CdTe thin film absorber using aqueous solution of CdSO4 and TeO2. Next CdCl2 dip followed by 400°C heat treatment was used to modify the CdTe/CdS surface and interface. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) were used to evaluate the resulting surface morphology. X-ray diffraction analysis reveals that the heat treatment enhances the recrystallisation and shifts the CdTe peaks towards a smaller lattice parameter.CdS/CdTe heterojunction was subjected to chemical treatment commonly used in photovoltaic device fabrication to determine the resulting microscopic effect on the morphology and structure. CdS and CdTe thin films were electrodeposited successively onto indium tin oxide (ITO) from aqueous solution. Containing CdCl2 and Na2S2O3 for the deposition of thin film windows, the ITO/CdS resulting substrates was then used for the deposition of CdTe thin film absorber using aqueous solution of CdSO4 and TeO2. Next CdCl2 dip followed by 400°C heat treatment was used to modify the CdTe/CdS surface and interface. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) were used to evaluate the resulting surface morphology. X-ray diffraction analysis reveals that the heat treatment enhances the recrystallisation and shifts the CdTe peaks towards a smaller lattice parameter

Nonradiative recombination and band bending of p Si 100 surfaces during electrochemical deposition of polycrystalline ZnO

In this study, zinc oxide ZnO thin films were cathodically deposited from aqueous zinc chloride solutions in the presence of oxygen on p Si 100 substrates using an electrochemical reaction. The change in nonradiative recombination and band bending of the Si surface was investigated in situ by pulsed photoluminescence and pulsed photovoltage techniques during the electrochemical deposition. The layers consisted of ZnO, small amounts of OH groups from Zn OH 2 and water and chloride ions. The morphology of the layers depend on the electrolyte composition, current density i.e. illumination intensity and applied potential. Low current densities lt; 0.5 mA cm2 lead to smooth and polycrystalline ZnO layers on p Si, where no SiOx interlayer has been observed. The band bending of p Si 100 was reduced by about 70 mV and nonradiative recombination increases only slightly during the deposition process with respect to the hydrogenated Si 100 surface

Influence of citrate ions as complexing agent for electrodeposition of CuInSe2 thin films

SCOPUS: ar.jinfo:eu-repo/semantics/publishe