Substrate Temperature-Dependent Physical Properties of Thermally Evaporated Sn_4Sb_6S_(13)Thin Films

In this work,the homogenous thin films of sulfosalt Sn_4Sb_6S_(13) were successfully synthesized by the thermal evaporation technique onto corning 7059 glass substrates heated at various temperatures in the range of 30-200 ℃.The surface morphology and structural characteristics of Sn_4Sb_6S_(13) films were analyzed by atomic force microscopy,X-ray diffraction,and energy-dispersive X-ray,respectively.The X-ray diffraction analysis revealed that Sn_4Sb_6S_(13) thin films crystallized in monoclinic structure according to a preferential direction(6 11).An improvement in the structural properties by increasing the substrate temperature was observed.The values of some important parameters such as absorption coefficient(α),band gap(E_g),refractive index(n),extinction coefficient(k),and dielectric constant(ε_∞) of thin film were determined.The absorption coefficient was larger than 10~5 cm~(-1) in the visible range.The electron transition of Sn_4Sb_6S_(13)films was direct allowed with the values that decreased(2-1.69 eV) by increasing substrate temperature from 30 to 200 ℃.The dispersion data obeyed the single oscillator relation of the Wemple-DiDomenico model and Cauchy model.The electrical free carrier susceptibility and the carrier concentration of the effective mass ratio were estimated according to the model of Spitzer and Fan.     

Properties of Band Gaps and Defect Modes Based on Fibonacci All Superconductor-Semiconductor Aperiodic Photonic Crystals

Journal of Superconductivity and Novel Magnetism - In this numerical simulation, we study a new optical device based on semiconductor-superconductor structures, showing narrower broadband...     

Synthesis, elaboration and characterization of the new material CuIn3S5 thin films

CuIn₃S₅ compound was prepared by direct reaction of high-purity elemental copper, indium and sulphur. CuIn₃S₅ thin films were prepared from powder by thermal evaporation under vacuum (10⁻⁶ mbar) onto glass substrates. The glass substrates were heated from 30 to 200 °C. The powder was characterized for their structural and compositional properties by using X-ray diffraction (XRD) and energy dispersive X-ray (EDAX). The XRD studies revealed that the powder exhibiting P-chalcopyrite structure. From the XRD data, we calculated the lattice parameters a and c. Then, the cation–anion bond lengths l _AC and l _BC are deduced. The films were characterized for their structural, compositional, morphological and optical properties by using XRD, EDAX, atomic force microscopy and optical measurement techniques (transmittance and reflectance). XRD analysis revealed that the films deposited at a room temperature (30 °C) are amorphous in nature, whereas those deposited on heated substrates (≥75 °C) were polycrystalline with a preferred orientation along (112) of the chalcopyrite phase. The surface morphological analysis revealed that the films grown at different substrate temperature had an average roughness between 1.1 and 4.8 nm. From the analysis of the transmission and reflection data, the values of direct and indirect band gap of the films were determined. We found that the optical band gap decreases when the substrate temperature increases.     

Effect of pH on the properties of ZnS thin films grown by chemical bath deposition

Zinc sulphide thin films have been deposited on glass substrates using the chemical bath deposition technique. The depositions were carried out in the pH range of 10 to 11.5. Structure of these films was characterized by X-ray diffraction and scanning electron microscopy. Optical properties were studied by spectrophotometric measurements. Influence of the increased pH value on structural and optical properties is described and discussed in terms of transmission improvement in the visible range. Transmission spectra indicate a high transmission coefficient (70%). The direct band gap energy is found to be about 3.67 eV for the films prepared at pH equal to 11.5.     

Optical constants of Zn-doped CuInS2 thin films

Optical properties of Zn-doped CuInS₂ thin films grown by double source thermal evaporation method have been studied. The amount of the Zn source was determined to be 0%-4% molecular weight compared with CuInS₂ source. After that, samples were annealed in vacuum at the temperature of 450 °C in quartz tube. The optical constants of the deposited films were obtained from the analysis of the experimental recorded transmission and reflexion spectral data over the wavelength range 300-1800 nm. It is observed that there is an increase in optical band gap with increasing Zn % molecular weight. It has been found that the refractive index and extinction coefficient are dependent on Zn incorporation. The complex dielectric constants of Zn-doped CuInS₂ films have been calculated in the investigated wavelength range. It was found that the refractive index dispersion data obeyed the single oscillator of the Wemple-DiDomenico model, from which the dispersion parameters and the high-frequency dielectric constant were determined. The electric free carrier susceptibility and the carrier concentration on the effective mass ratio were estimated according to the model of Spitzer and Fan.     

Comparative study of structural and morphological properties of CuIn3S5 and CuIn7S11 materials

CuIn₃S₅ and CuIn₇S₁₁ powders were prepared by solid-state reaction method using high-purity elemental copper, indium and sulphur. The films prepared from CuIn₃S₅ and CuIn₇S₁₁ powders were grown by thermal evaporation under vacuum (10^?6 Torr) on glass substrates at different substrate temperature Ts varying from room temperature to 200 °C. The powders and thin films were characterized for their structural properties by using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). Both powders were polycrystalline with chalcopyrite and spinel structure, respectively. From the XRD data, we calculated the lattice parameters of the structure for the compounds. For CuIn₃S₅ powder, we also calculated the cation–anion bond lengths. The effect of substrate temperature Ts on the structural properties of the films, such as crystal phase, preferred orientation and crystallinity was investigated. Indeed, X-ray diffraction analysis revealed that the films deposited at a room temperature (30 °C) are amorphous in nature while those deposited on heated were polycrystalline with a preferred orientation along (1 1 2) of the chalcopyrite phase and (3 1 1) of the spinel phase for CuIn₃S₅ and CuIn₇S₁₁ films prepared from powders, respectively. The morphology of the films was determined by atomic force microscopy AFM. The surface roughness and the grain size of the films increase on increasing the substrate temperature.     

Effect of antimony incorporation on structural properties of CuInS2 crystals

CuInS₂ (CIS) single crystals doped with 1, 2, 3 and 4 atomic percent (at.%) of antimony (Sb) were grown by the horizontal Bridgman method. The effect of Sb doping on the structural properties of CIS crystal was studied by means of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and PL measurements. X-ray diffraction data suggests that the doping of Sb in the CIS single crystals does not affect the tetragonal (chalcopyrite) crystal structure and exhibited a (1 1 2) preferred orientation. In addition, with increasing Sb concentration, the X-ray diffraction analysis show that Sb doped CIS crystals are more crystallized and the diffraction peaks of the CuInS₂ phase were more pronounced in particular the (1 1 2) plane. EDAX study revealed that Sb atoms can occupy the indium site and/or occupying the sulfur site to make an acceptor. PL spectra of undoped and Sb doped CIS crystals show two emission peaks at 1.52 and 1.62 eV, respectively which decreased with increasing atomic percent antimony. Sb doped CIS crystals show p-type conductivity.     

Breakdown electric field calculations of hot SF/sub 6/ for high voltage circuit breaker applications

The critical reduced electric field strengths of hot SF/sub 6/ corresponding to the dielectric recovery phase of a high voltage circuit breaker are calculated for a large temperature range (300-3000 K). Calculations are based on a multi-term Boltzmann equation solution using, in comparison to the literature works, improved cross section sets for the interactions of electrons with various SF/sub 6/ dissociated products. The obtained critical electric fields show a reasonable agreement with the available data. These results are then used in hydrodynamics simulations which correctly predicts the circuit breaker behaviors observed in the case of a successful breaking test as well as in a failed one.     

A comparative study of the properties of thermally evaporated CuIn2n + 1S3n + 2 (n = 0, 1, 2 and 3) thin films

CuInS₂, CuIn₃S₅, CuIn₅S₈ and CuIn₇S₁₁ compounds were synthesized by the horizontal Bridgman method using high-purity copper, indium and sulphur elements. Crushed powders of these ingots were used as raw materials for the vacuum thermal evaporation. So, CuIn_2n + 1S_3n + 2 (n = 0, 1, 2, and 3) thin films were deposited by single source vacuum thermal evaporation onto glass substrates heated at 150 °C. The structural, compositional, morphological, electrical and optical properties of the deposited films were studied using X-ray diffraction (XRD), energy dispersive X-ray, atomic force microscopy and optical measurement techniques. XRD results revealed that all the films are polycrystalline. However, CuInS₂ and CuIn₃S₅ films had a chalcopyrite structure with preferred orientation along 112 while CuIn₅S₈ and CuIn₇S₁₁ films exhibit a spinel structure with preferred orientation along 311. The absorption coefficients of the all CuIn_2n + 1S_3n + 2 films are in the range of 10⁻⁴ and 10⁻⁵ cm⁻¹. The direct optical band gaps of CuIn_2n + 1S_3n + 2 layers are found to be 1.56, 1.78, 1.75 and 1.30 eV for n = 0, 1, 2, and 3, respectively. CuIn₃S₅ and CuIn₅S₈ films are p type with electrical resistivities of 4 and 12 Ω cm whereas CuInS₂ and CuIn₇S₁₁ are highly compensated with resistivities of 1470 and 1176 Ω cm, respectively.