Search

Barium strontium titanate (BST) (BaSrTiO) thin films have been extensively used in many dielectric devices such as dynamic random access memories (DRAMs). To optimize its characteristics, a microstructural control is essential. In this paper, BaSrTiO thin film has been deposited on the SiO/Si substrate by the pulsed laser deposition (PLD) technique at three different oxygen working pressures of 100, 220 and 350 mTorr. Then the deposited thin films at 100 mTorr oxygen pressure were annealed for 50 min in oxygen ambient at three different temperatures: 650, 720 and 800°C. The effect of oxygen working pressure during laser ablation and thermal treatment on the films was investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis methods. X-ray photoelectron spectroscopy analysis was used to determine the surface chemical composition of the samples. The results indicate that the deposited BST film at low working pressure (100 mTorr) in PLD chamber shows a lower surface roughness than other working pressures (220 and 350 mTorr). The as-deposited films show an amorphous structure and would turn into polycrystalline structure at annealing temperature above 650°C. Increase of temperature would cause the formation of cubic and perovskite phases, improvement in crystalline peaks and also result in the decomposition of BST at high temperature (above 800°C). In addition, rising of temperature leads to the increase in size of grains and clusters. Therefore more roughness was found at higher temperatures as a result of a more heterogeneous growth and less tensions. [ABSTRACT FROM AUTHOR]

Abstract: The morphological characteristics and electronic structure of the BaTiO3 films grown by pulsed-laser deposition technique have been investigated. AFM and FE-SEM images reveal columnar growth characteristic of these films. Utilizing spectrophotometer, optical band gap of the films were reckoned to be about 3.76eV. Both dα/dE and PL vs. E plots reveal numerous luminance states in the gap. Despite the presence of many luminance faults in the gap, cations manage to preserve their electronic states. [Copyright &y& Elsevier]

[Display omitted] • Cu 2 SnS 3 thin films were deposited using the spray pyrolysis deposition. • Stable basic molecular solution is used as spray precursor using ethylenediamine as capping agent. • The effect of the most important parameters including the substrate temperature and copper concentration was investigated. • Qualified thin films with suitable microstructure and composition could be deposited at 370℃. • Carrier concentration of the samples rise as the Cu/Sn ratio is enhanced and Cu/Sn = 1 show a semiconductor behavior. This work focused on the spray pyrolysis deposition of Cu 2 SnS 3 (CTS) thin films using a stable basic solution. The effect of the most important parameters including the substrate temperature and copper concentration on the structural, optical and electrical properties of as-deposited thin films was investigated. Qualified thin films with suitable microstructure and composition could be deposited at 370℃. XRD and Raman analysis while confirming the pure CTS film formation, show that as the Cu/Sn decreases, the crystal structure layers are changed from the tetragonal phase to the cubic phase mixed with Sn-rich phases. The optical study shows its band gap between 1.08 and 1.2 eV for different Cu/Sn ratios with the absorption coefficient being more than 10 4 cm - 1 . The Hall and Mott-Schottky measurements reveal that all samples show a p-type behavior and carrier concentration of the samples rise as the Cu/Sn ratio is enhanced. A full spray superstrate solar cell based on CTS (Cu/Sn = 1 with a semiconductor behavior) resulted in an efficiency of 0.63%. [ABSTRACT FROM AUTHOR]

Abstract: The electronic conductor-insulator transition in Ca-doped BiFeO3 films grown by pulsed-laser deposition technique has been investigated. Nature of the transition is resolved to be Mott type through the control of band-filling. Calcium resolved to have colossal effect on enhancing the electrical conductivity of BiFeO3, but it did not affect band gap of the mother phase perceptibly. UV-visible study yielded band gap of 2.72-2.81eV (at 300K) for different concentrations of calcium. Both UV-visible and photoluminescence spectra revealed sub-band gap transitions at 2.17 and 2.38eV, of which the latter might be ascribed to the oxygen vacancies. [Copyright &y& Elsevier]

• CZTS thin films were deposited by the PLD technique. • The effect of substrate temperature was investigated systematically. • Without the sulfurization process, the single-phase CZTS is prepared at a low temperature of 300 ℃. • The simulation was run to study the effect of substrate/Mo/MoSe 2 on the pure sulfide kesterite solar cells. • An improvement in conversion efficiency from 5.4% to 13.99% has been predicted. Targeting on the selenium free, pure sulfide kesterite compound (CZTS) allows retention of the higher band gap nontoxic absorber for a single-junction solar cell. In this work, CZTS thin films were deposited by the PLD method and the Structural/optical properties, as well as Mott–Schottky analysis, were studied at different substrate temperatures. Without undergoing the sulfurization process, the single-phase CZTS thin film is prepared at 300 ℃. In the second step, a numerical simulation is performed using the solar cell capacitance simulator to study the effect of the grading layer of MoS(Se) 2 on the rear side of pure sulfide kesterite based solar cells. The device with a MoSe 2 coated substrate exhibits better performance in comparison with the soda-lime-glass (SLG)/Mo that is susceptible to the formation of an n-type MoS 2 intermediate layer. An improvement in conversion efficiency from 5.4% to 13.99%, often due to an increase of open-circuit voltage has been reached. [ABSTRACT FROM AUTHOR]