The effect of the film thickness and doping content of SnO2:F thin films prepared by the ultrasonic spray method

This paper reports on the effects of film thickness and doping content on the optical and electrical properties of fluorine-doped tin oxide. Tin(II) chloride dehydrate, ammonium fluoride dehydrate, ethanol and HCl were used as the starting materials, dopant source, solvent and stabilizer, respectively. The doped films were deposited on a glass substrate at different concentrations varying between 0 and 5 wt% using an ultrasonic spray technique. The SnO2 :F thin films were deposited at a 350 C pending time(5, 15, 60 and 90 s). The average transmission was about 80%, and the films were thus transparent in the visible region. The optical energy gap of the doped films with 2.5 wt% F was found to increase from 3.47 to 3.89 eV with increasing film thickness, and increased after doping at 5 wt%. The decrease in the Urbach energy of the SnO2:F thin films indicated a decrease in the defects. The increase in the electrical conductivity of the films reached maximum values of 278.9 and 281.9( cm)1for 2.5 and 5 wt% F, respectively, indicating that the films exhibited an n-type semiconducting nature. A systematic study on the influence of film thickness and doping content on the properties of SnO2:F thin films deposited by ultrasonic spray was reported.     

Microstructure and magnetic properties of In1−xCrxN thin films

Microstructure and magnetic properties of In_1−xCr_xN thin films grown on GaN-on-sapphire templates by molecular beam epitaxy are investigated. Optimized growth conditions are identified for the In_1−xCr_xN thin films at reduced growth temperature. The In_1−xCr_xN thin films on the top of the InGaN buffer layers exhibit high crystalline-quality. The magnetic properties of In_1−xCr_xN thin films show a ferromagnetic behavior even at room temperature.     

Effect of Fe doping on structural and magnetic properties of La2/3Ca1/3Mn1−yFeyO3 (y=0–0.03) thin films

We have characterized the magnetic and structural properties of pure and ⁵⁷Fe-doped La_2/3Ca_1/3MnO₃ thin films and targets, substituted with 1% and 3% of ⁵⁷Fe on the Mn site. The films were prepared via high O₂-pressure (500 mTorr) by DC magnetron sputtering on (1 0 0) SrTiO₃ and (1 0 0) LaAlO₃ single-crystal substrates. Mössbauer spectra measured at room temperature confirm the presence of Fe³⁺ with octahedral coordination, thus indicating that Fe is incorporated into the structure by substituting Mn. Structural analysis by X-ray diffraction (XRD) shows that the films are single phase and c-axis oriented and that the Fe doping gives rise to a relaxation of the epitaxial strain. Interestingly, the Curie temperature and the magnetoresistance (MR) show a non-monotonic behavior with Fe doping. This indicates that initially the strain relaxation induced by the Fe doping is more important than the reduction of ferromagnetic coupling due to the Fe incorporation.     

Effect of Se content on the structural,morphological and optical properties of Bi2Te3−ySey thin films electrodeposited by under potential deposition technique

Bi₂Te_3−ySe_y thin films with different Se contents ranging from 0.3 to 2.5 were successfully electrodeposited by under potential deposition (UPD) technique onto gold foil substrates from an electrolyte consist of Bi(NO₃)₃, TeO₂, and SeO₂ at ambient conditions. The effects of Se content on structural, morphological and optical properties of the products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectroscopy, respectively. The XRD analysis revealed that the diffraction peaks positions of Bi₂Te_3−ySe_y thin films shifts gradually towards the higher angle side due to replacement of Te by Se atoms in the crystal structure with increasing Se content. The SEM results showed that the particle size of Bi₂Te_3−ySe_y thin films decreased as the Se content increased. The optical constants of ternary Bi₂Te_3−ySe_y thin films such as refractive index, extinction coefficient, and dielectric constant were obtained from the transmission spectra in the range of 2500–10.000 nm. The direct allowed band gap energies were estimated using Tauc equation and found to increase from 0.210 to 0.282 eV with increasing Se content from 0.3 to 2.5. The dispersion behavior of refractive index was studied by the single oscillator Wemple-DiDomenico model.     

Structural characterization of Zn1−xCdxO (0≤x≤0.20) microrods grown by spray pyrolysis

Zn_1−xCd_xO (x= 0.00, 0.05, 0.10, 0.15 and 0.20) thin films were obtained by spray pyrolysis and characterized by XRD, SEM, EDAX and optical measurements. The Zn_1−xCd_xO microrods are in the wurtzite crystallographic phase with (0 0 2) preferred orientation. A narrowing of the fundamental band gap from 3.30 to 3.10 eV was observed with the increasing nominal Cd content up to 20 at% due to the direct modulation of the band gap caused by Cd substitution. The undoped ZnO film showed two emission bands in the spectra: one sharp UV luminescence at ∼382 nm and one broad visible emission ranging from 430 to 600 nm. The sharp peak at ∼382 nm is split into two at 376 and 400 nm upon Cd doping at levels of 5 and 10 at%. However this splitting is not observed in the doped ZnO samples containing 15 at% Cd and more. It should also be mentioned that the broad peak at the range of 430–600 nm has almost disappeared in the films containing 5, 10 and 15 at% Cd.     

Effect of bath temperature on the properties of CuIn_χGa_(1-χ)Se_2 thin films grown by the electrodeposition technique

Electrodeposition is a promising and low cost method to synthesize CuIn_xGa_(1-x)Se_2(CIGS)thin films as an absorber layer for solar cells.The effect of bath temperature on the properties of CIGS thin films was investigated in this paper.CIGS films of 1μm thickness were electrodeposited potentiostatically from aqueous solution,containing trisodium citrate as a complexing agent,on Mo/glass substrate under a voltage of-0.75 V,and bath temperatures were varied from 20 to 60℃.The effects of bath temperature ...     

Growth of high quality YbBa2Cu3O7−δ thin films by pulsed laser deposition

YbBa₂Cu₃O_7−δ (Yb-123) films are deposited for the first time using Pulsed Laser Deposition (PLD) method at three different substrate temperatures, viz. 675°C, 700°C and 725°C. Films are characterized using XRD, dc electrical resistivity, critical current density (J_c) and microstructural study by Atomic Force Microscopy (AFM) techniques. It is found that 700°C is the optimum growth temperature for growing high quality Yb-123 films. The best T_c and J_c values obtained at optimum growth conditions are 88 K and 2.6×10⁶ A cm⁻² at 77 K, respectively. AFM photographs provide evidence in confirming the relation between growth temperature and superconducting properties.     

Influence of substrate type on the structural,optical and electrical properties of CdxZn1−xS MSM thin films prepared by Spray Pyrolysis method

0.25 μm Cd_xZn_1−xS thin films were deposited on Si and glass substrates by using a chemical Spray Pyrolysis technique (CSP). Measurements of the absorption spectrum of the film were carried out. The values of band gaps (E_g) are calculated from the absorption spectrum. X-ray diffraction (XRD) of the Cd_xZn_1−xS thin films on Si and glass substrates was carried out. The full width at half-maximum (FWHM)) of diffraction peak was calculated to be about 0.640, which showed that it is a polycrystalline thin film. A Cd_xZn_1−xS Metal–Semiconductor–Metal (MSM) photodetector with nickel (Ni) contact electrodes was then fabricated. The electrical property of the Ni/Cd_xZn_1−xS/Si and Ni/Cd_xZn_1−xS/glass detectors was investigated using the current–voltage (I–V) measurements. The barrier heights ϕ_Β of Ni/Cd_xZn_1−xS/Ni MSM on Si and glass substrates were 0.551 eV and 0.593 eV, respectively with an applied bias voltage of 3 V.     

Cu(In1-xGax)Se2薄膜太阳电池的J-V特性

对Cu（In1-xGax）Se2（CIGS）太阳电池J-V特性曲线进行了测试和分析,采用Matlab软件进行计算,得到电池的二极管品质因子、反向饱和电流密度、串联电阻、并联电阻等特性参数，采用数值逼近法,将得到的参数回归J-V方程,与测试结果符合较好，对不同光照强度下电池的特性参数进行计算,发现并联电阻随光照强度增加而降低,并分析了原因。     

Cu(In1-xGax)Se2薄膜太阳电池的J-V特性

对Cu(In1-xGax)Se2(CIGS)太阳电池J-V特性曲线进行了测试和分析,采用Matlab软件进行计算,得到电池的二极管品质因子、反向饱和电流密度、串联电阻、并联电阻等特性参数.采用数值逼近法,将得到的参数回归J-V方程,与测试结果符合较好.对不同光照强度下电池的特性参数进行计算,发现并联电阻随光照强度增加而降低,并分析了原因.     

Characterization of ternary MgxZn1−xO thin films deposited by electron beam evaporation

Mg_xZn_1−xO (0≤x≤1) thin films were deposited on glass and quartz substrates by electron beam evaporation and effect of the Mg content of the film on its structural, optical and electrical properties were investigated. The structure, surface morphology, optical transmittance, band gap, refractive index and electrical resistivity were found to depend on the Mg content of the film. XRD data revealed that films were polycrystalline in nature. The structure of the films having Mg content in the range of 1–0.74 was cubic, mixed cubic-hexagonal phases for x=0.47 and hexagonal phase for x=0. The composition analysis showed that Mg content in Mg_xZn_1−xO film is high as compared to the corresponding target alloy. It was observed that the optical band gap increases from 3.3 to 6.09 eV, refractive index at 550 nm decreases from 1.99 to 1.75, transmittance increases from about 70% to 90% and electrical resistivity increases from 0.5 to 1.48×10⁶ Ω cm with the increase of Mg concentration in the film from 0 to 1. The results reported in this work are useful for window layer of solar cells and other optoelectronic devices.     

Effect of residual stress on critical current density of YBa2Cu3O7−x thick films

YBa₂Cu₃O_x films were fabricated on 10-cm-diameter polycrystalline MgO wafers by spray pryolysis of a metal acetate solution. In-plane residual stress of the films was obtained by shadow Moiré interferometry and correlated with crack formation and critical current density. High tensile stresses (0.96 GPa) were measured at the wafer center and decreased toward the edge, which corresponded with the largest number of cracks and lowest critical current density at the wafer center. A major cause of the residual stress (0.5 GPa) was caused by a tetragonal-to-orthorhombic phase transition in YBa₂Cu₃O_x.     

Effect of Fe Substitution on Thermoelectric Properties of Fe x In4−x Se3 Compounds

Starting from elemental powder mixtures of Fe _x In_4?x Se₃ (x = 0, 0.05, 0.1, 0.15), polycrystalline In₄Se₃-based compounds with homogeneous microstructures were prepared by mechanical alloying (MA) and hot pressing (HP). With the increase of x from 0 to 0.15, the electrical resistivity and the absolute value of the Seebeck coefficient increased, while the thermal conductivity first decreased and then increased. The maximal dimensionless figure of merit ZT of 0.44 was obtained for the Fe _x In_4?x Se₃ (x = 0.05) sample at 723 K.     

Spray pyrolysis deposition of Cu–Zn–In–S solid-solution thin films with tunable compositions and band gaps

Cu–Zn–In–S solid solution thin films with tunable compositions and band gaps were deposited on glass substrates using a chemical spray pyrolysis approach. XRD results reveal the cubic-structured Cu–Zn–In–S films without detectable impurities. The successive shift of XRD patterns toward high-angle side of ZnS with increasing ZnS molar fraction in products proves a formation of Cu–Zn–In–S solid solutions. SEM images and EDAX analyses demonstrate homogeneous surface morphologies and adjustable compositions of Cu–Zn–In–S films, which results in film band gaps broadly tunable from 1.54 eV to 3.61 eV. These sprayed Cu–Zn–In–S solid solution thin films may find potential uses in photovoltaics and photocatalysis.     

Cadmium(1−x)zinc(x)telluride thin films deposited by sequential pulsed laser deposition

In this work, sequential pulsed laser deposition was used for the deposition of cadmium zinc telluride (CZT) thin films. CZT is a ternary II–VI compound semiconductor with a tunable band gap between 1.51 and 2.26 eV. In this work, three different CZT film compositions were achieved at room temperature by sequential deposition of nanometric layers with a precise number of laser shots on the cadmium telluride (CdTe) and zinc telluride (ZnTe) targets. XPS, XRD and UV–vis transmittance techniques were used to characterize the CZT films. The atomic content of zinc ranged from 60% down to 13%. This represents an enlargement of the lattice constant from 6.19 to 6.41 Å, and a band gap decrement from 1.94 to 1.55 eV. In addition, the CZT film resistivity can be modulated between the CdTe (4.1×10⁷ Ω-cm) and ZnTe (2.8×10⁵ Ω-cm) values. Our results demonstrated that the sequential pulsed laser deposition can be used to obtain several CZT film compositions with precise control of its stoichiometry and can be extended to the production of other ternary compounds.     

Possibility of obtaining the (GaSb)1 − x (Si2) x films on silicon substrates by the method of liquid-phase epitaxy

Semiconductors - It is shown that it is possible to grow a continuous series of (GaSb)1 ? x (Si2) x (x = 0?1) alloys on silicon substrates by the method of liquid-phase epitaxy from a...     

Superconducting and structural characteristics of YBa2Cu3O7−x thin films on si(001) substrates with YSZ buffer layers

We have prepared high quality c-axis oriented superconducting YBa₂Cu₃O_7−x thin films on Si(001) substrates covered with YSZ = (ZrO₂ + 10 at.% Y₂O₃) layers by an in situ high pressure (3–5 mbar) oxygen d.c./r.f. sputtering process at substrate temperatures of about 750°C. The films were characterized by X-ray diffraction, transmission electron microscopy (TEM) and electron scanning (SEM) techniques. A superconducting transition temperature T_c(R− 0) = 89 K was determined by resistivity and susceptibility measurements. Cross sectional TEM analysis showed a sharp interface between YSZ and Si; however an inter diffusion zone was observed between YSZ and YBa₂Cu₃O_7−x layers.     

Effect of the chemical composition of Cu–In–Ga–Se layers on the photoconductivity and conversion efficiency of CdS/CIGSe solar cells

The effect of the [Ga]/[In+Ga] ratio of gallium and indium on the microwave photoconductivity of Cu–In–Ga–Se (CIGSe) films and on the efficiency of solar cells fabricated in accordance with the same technology is investigated. According to the observations of a field-emission scanning electron microscopy (FESEM), the grain size decreases with increasing Ga content. With increasing gallium content in the samples, the photogenerated-electron lifetime and the activation energy of the microwave photoconductivity also decrease. The changes in the activation energy of the through conduction in darkness are less than 20%. Analysis of the obtained data shows that the known effect of the gallium gradient on the efficiency should be associated with modification of the internal structure of grains instead of with their boundaries.     

Study of the recombination process at crystallite boundaries in CuIn1 − x Ga x Se2 (CIGS) films by microwave photoconductivity

The loss kinetics of photogenerated charge carriers in thin polycrystalline chalcopyrite CuIn_1?x Ga _x Se₂ (CIGS) films has been studied by microwave photoconductivity (at 36 GHz). The films were synthesized using the ampoule method and three variants of physical vapor deposition with subsequent selenization: magnetron sputtering, thermal deposition, and modified thermal deposition with intermetallic precursors. The photoconductivity was excited by 8-ns nitrogen laser pulses with maximum intensity of 4 × 10¹⁴ photons/cm per pulse. Measurements were performed in the temperature range 148–293 K. The photoresponse amplitude is found to depend linearly on the sizes of coherent-scattering regions in the film grains, which were calculated from X-ray diffraction data. The photoresponse decay obeys hyperbolic law. The photoresponse half-decay time increases with a decrease in both temperature and light intensity. It is shown that the recombination of free holes with trapped electrons is very efficient near the crystallite boundaries.