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A simple and hydrazine-free solution-based approach for depositing (CZTS) and (CZTSSe) absorber layers is reported. The process involves incorporating metal salts and thiourea into a single pyridine-based solution, spin-coating a precursor film, and sulfurizing with sulfur powders or selenizing using pellets in an inert atmosphere, to form the desired CZTS or CZTSSe films. X-ray diffraction and Raman spectra studies show that kesterite CZTS and CZTSSe are formed after sulfurization and selenization, respectively. The selenized CZTSSe displays higher crystallinity than the sulfurized CZTS. Photovoltaic devices (glass//CZTSSe//i-/n-/A) employing the solution precursor selenized at 500°C have yielded power conversion efficiency of 1.44% under AM 1.5 illumination. [ABSTRACT FROM AUTHOR]

Single-phase CuInSe2 films were grown by high vapor selenization of CuIn alloy precursors within a partially closed graphite box. The CuIn precursors were prepared using CuxIny alloy targets with different composition rates under low vacuum level by a homemade sputtering system. The Cu and In composition rates of the used targets are 11:9, 10:10, and 9:11, respectively. The metallic precursor films were selenized using a two-step temperature profile, i.e. at 250°C and 400–500°C, respectively. The influence of the temperature at the second selenization step on the quality of the CIS absorbing layers was investigated. The CIS films were characterized by X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The deposited CIS absorbers selenized at a high temperature of 500°C for 30 min exhibited a single-phase chalcopyrite structure with a preferential orientation in the (112) direction. These layers display uniform, large, and densely packed crystals with a grain size of about 3–5 μm. Cadmium sulfide buffer layer was manufactured by chemical bath deposition method. Bilayers ZnO/ZnO:Al were prepared by RF magnetron sputtering deposition. CIS solar cells with an efficiency of about 6.5% were produced without antireflective films. The method to fabricate CIS solar cells by a combination of the low vacuum sputtering deposition and the graphite box selenization process has provided a simple control process and shown a promising potential for developing high efficient and low-cost CuInSe2 solar cells. [ABSTRACT FROM AUTHOR]

Growth mechanisms and defects formation of the manganese mercury thiocyanate (MMTC) crystal have been investigated by atomic force microscopy (AFM). Both screw dislocation controlled growth and 2D nucleation growth occur on the {110} faces. Stacking faults are observed among dislocation hillocks and the formation of them probably results from the different crystallization orientations of different spirals. Hollow channels are found around the nucleation islands and the formation of them is due to the instability of the interface generated by the rapid nucleation and growth speeds. [ABSTRACT FROM AUTHOR]

The effect of annealing temperature on the magnetic and giant magnetostriction (GMS) of [Fe/Tb/Fe/Dy]n multilayer films were investigated. X-ray diffraction showed that the multilayer films' microstructures were still in amorphous at annealing temperature 300°C. The multilayer films began to crystalline at annealing temperature 400°C. The saturation magnetization of multilayer films increased by the increasing annealed temperature. The coercivity first decreased at annealing temperature 300°C and then increased when the annealing temperature was higher than 400°C. The multilayer films had good low-field GMS, and the magnetostriction of the multilayer films increased by the increasing annealing temperature. [ABSTRACT FROM AUTHOR]

An improved chemical bath deposition (CBD) technique has been provided to prepare zinc sulfide (ZnS) thin films on glass substrates deposited at 80–82°C using a mixed aqueous solution of zinc sulfate, ammonium sulfate, thiourea, hydrazine hydrate, and ammonia at the alkaline conditions. Both the traditional magnetic agitation and the substrates vibration by hand frequently were done simultaneously during the deposition. The substrates vibration reduced the formation and residence of gas bubbles on the glass substrates during growth and resulted in growth of clean ZnS thin films with high quality. Ammonia and hydrazine hydrate were used as complexing agents. It is found that hydrazine hydrate played an important role in growth of ZnS films. The structure and microstructure of ZnS films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-vis spectroscopic methods. The XRD showed a hexagonal structure. The formed ZnS films exhibited good optical properties with high transmittance in the visible region and the band gap value was estimated to be 3.5–3.70 eV. [ABSTRACT FROM AUTHOR]

The magnetic properties and giant magnetostriction effect (GMS) of the amorphous alternant [Tb/Fe/Dy]n (named S1) and [Fe/Tb/Fe/Dy]m (named S2) nano-multilayer films have been studied. The magnetic hysteresis loops show that easy magnetic direction changes from perpendicular to the film plane (S1) to parallel to the film plane (S2). S2 has better soft magnetic properties and low-field giant magnetostriction effect than that of S1, due to the exchanging interaction between the hard GMS layer and the soft layer Fe. The different magnetic behavior is explained by considering the nature of the magnetization process, i.e. domain-wall motion and spin rotation. [ABSTRACT FROM AUTHOR]

Copper indium diselenide (CuInSe2) thin films were grown on indium–tin oxide (ITO)/soda-lime glass using a one-step cathodic electrodeposition process at potentials lower than -0.6 V vs SCE, and in the presence of a large excess of In3+. The source solution contained CuCl2, InCl3, and H2SeO3 complexed by citric acid. The concentration of InCl3 in the electrochemical bath affected the structure, composition, stoichiometric ratio, and morphological properties of electrodeposited films. CuInSe2 films with a chalcopyrite structure and quite good stoichiometry were directly electrodeposited from a solution of 20 mM InCl3, 5 mM CuCl2, and 8 mM H2SeO3. Annealing of these CuInSe2 films in the temperature range from 300°C to 500°C improves their crystallinity and increases their grain size. Good chalcopyrite CuInSe2 films with a (112) preferential orientation suitable for the production of efficient solar cells are obtained after annealing at 500°C. The formation mechanism of the ternary CuInSe2 compound during the electrodeposition process was discussed. [ABSTRACT FROM AUTHOR]

A simply modified bath deposition technique has been successfully used to deposit uniform CdS thin films using cadmium chloride or cadmium acetate as the cadmium ion source, and thiourea as the sulfur source on glass substrates. Both the traditional magnetic agitation and the frequent substrate vibration by hand were done simultaneously during the deposition. Various properties of the deposited films such as surface morphology, crystallinity, and optical properties were investigated. The CdS films deposited from cadmium acetate show a good crystallinity and exhibit a preferential orientation along the hexagonal (002) direction. Their surface morphologies are more homogeneous with smaller grains than those from cadmium chloride. The CdS films prepared from both cadmium ion sources present a high optical transmission (more than 80%) in the visible range with the band gap value of about 2.4 eV. The substrate vibration reduces the formation and residence of gas bubbles on the glass substrate during growth and resulted in deposition of CdS thin films with high quality. XRD, SEM, and UV–Vis measurements have provided the supported data. The fundamental CBD growth mechanisms involving different cadmium salts are discussed. [ABSTRACT FROM AUTHOR]

Intrinsic zinc oxide (i-ZnO) film was prepared for CuInSe2 (CIS) solar cell application [L. Stolt and J. Hedstrom, Appl. Phys. Lett.62 (1993) 8; D. Rudmann, Ph.D. Thesis, University of Basel, Basel, (2004)] on glass substrate by inductively coupled plasma (ICP)-assisted DC magnetron sputtering and under a quite low temperature of 50°C. The sputtering was done in an Ar and O2 gas mixture and a ceramic ZnO target was used. The microstructures of the film were investigated by X-ray diffractometer and scanning electron microscope. It was shown that all of the films had a c-axis preferred orientation perpendicular to the substrate. In our work, film with resistivity of 7 × 108Ω·cm and transmittance of about 80% in the visible range was prepared under the conditions of 4 mTorr working pressure and 50°C temperature. [ABSTRACT FROM AUTHOR]

As the carbon nanotubes (CNTs) films are applied to the field emission cathodes in the vacuum devices, heat treatment in the range of 400°C–500°C is often conducted during the device sealing process, especially for glass-based devices. The annealing temperature effect on the field emission of the CNT films prepared by chemical vapor deposition is investigated. The CNT film annealed at 400°C in air contains less amorphous carbon phase, and shows better field emission properties comparing to the as-grown CNT film. Annealing at 450°C causes serious oxidative damage along the tube walls, resulting in the poor field emission performance. The CNTs annealed at 500°C are all burned out. The experiment shows that the sealing temperature at 400°C or below can be conducted in air, while the sealing temperature above 400°C should be done in N2 or Ar ambient. [ABSTRACT FROM AUTHOR]

Single crystals of nonlinear optical material, L-arginine trifluoroacetate (abbreviated as LATF), were grown from an aqueous solution by the low temperature solution growth method. The cell parameters of the grown crystal were determined by the X-ray powder diffraction analysis. Atomic force microscopy (AFM) was used to investigate the surface morphology of {101} cleavage faces of LATF. Straight steps and two-dimensional nuclei were observed. Liquid inclusions and impurities as defects for revealing macrosteps were demonstrated. The molecular structure and crystal structure correlative with surface morphology were discussed. [ABSTRACT FROM AUTHOR]

The dynamics and the conditions of amorphous transitions induced in a Ge1Sb2Te4 system upon a single femtosecond (fs) pulse melting were studied by real-time reflectivity measurements. The system has a multilayer structure of 100 nm ZnS–SiO2/(15–100 nm) Ge1Sb2Te4/120 nm ZnS–SiO2/0.6 mm polycarbonate substrate. It is shown that under optimum conditions amorphization is completed within 900 ps. The thickness of the phase change layer plays an important role in controlling the heat flow conditions in the system upon a fs pulse irradiation. The use of the fs laser pulse leads to a situation in which the pulse energy is deposited within a very short time in a thin surface layer, leading to heating or melting. The so-generated steep temperature gradient is subsequently smoothed by heat diffusion toward the substrate. The relative thermal process and effects are estimated. The calculated results are consisted with those from real-time reflectivity measurements. The mechanism of crystalline to amorphous transition triggered by single fs laser pulses is discussed. [ABSTRACT FROM AUTHOR]

Electrosorption of carbon nanotube and nanofiber (CNT–CNF) composite film electrodes was studied as a new desalination technology. The CNT–CNF composite film electrodes were grown on nickel sheets by low pressure thermal chemical vapor deposition. Different growth conditions at different acetylene flow rates of CNT–CNF composite film electrodes have been performed to obtain different crystallinities. The electrosorption experiments and Raman spectra analysis show the successful removal of ions with CNT–CNF composite film electrodes, depending on the optimal degree of crystalline perfection. In our work, optimal electrosorption was realized for the CNT–CNF composite film electrodes growing at 550°C with the acetylene and hydrogen flow rates of 30 and 200 sccm. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) thin films were prepared by radio frequency (RF) magnetron sputtering and under a quite low vacuum level of 2.3 × 10-3Pa. The sputtering was done in an Ar and O2 gas mixture at a temperature of 200°C. A ceramic In2O3:SnO2 target (10 wt% SnO2) was used. The microstructures of the films were investigated by a field emission scanning electron microscope (FESEM) and an X-ray diffractometer (XRD). X-ray photoelectron spectroscopy (XPS) was performed to characterize the composition of the films. ITO films with a high transparency in the visible wavelength range (80–95%) were obtained. The dependency of the electrical, optical and structural properties of ITO films on both the O2 flow ratio (O2/(O2 + Ar)) and the working pressure was investigated. In the case of low working pressure (1 Pa), the more highly transparent and conducting films were produced at the lower O2 flow ratio. High working pressure (2 Pa) gave rise to low quality, low transparency and amorphous films. Under RF sputtering at low vacuum level, the main contribution to the chamber atmosphere is due to water vapor. Oxygen originating from water vapor dissociation induced by plasma plays the same role as an oxygen or water vapor flux usually intentionally introduced in the system in order to have good quality films. [ABSTRACT FROM AUTHOR]

Polycrystalline silicon carbide (P-SiC) films containing SiC nanoparticles and Er were prepared by r.f. reactive magnetron co-sputtering technique with SiC and Er targets on low-temperature silicon (111) and silicon dioxide substrates with the mixed gas of pure argon, methane, and hydrogen. Surface morphology and photoluminescence (PL) properties of them were measured by field-emission scanning electron microscope and Raman spectroscopy. The peak position, intensity, and the full width at half maximum (FWHM) of PL spectra were relevant with Er doping levels and deposition conditions. [ABSTRACT FROM AUTHOR]

The unique electron field emission properties of carbon nanotube films are promising for fiat panel display application as the cold cathode. In this work, the multiwall carbon nanotube (10-10² nm in diameter, and 10³-10[sup 4] nm in length) film arrays (the pixel size: 50 µm × 50 µm) were deposited on the patterned Ni-Si substrate from hydrocarbon precursor (C[sub 2]H[sub 2]/H[sub 2]) by chemical vapor deposition at low temperature (550°C). The patterned films were characterized by scanning electron microscopy and Raman spectroscopy. The carbon nanotube film arrays exhibit good electron emission properties, e.g. low threshold emission field (below 2 V/µm), high emission current density (above 1 mA/cm² at 10 V/µm), and high emission luminance spot density on the phosphor coated-ITO(indium tin oxide)glass anode. These properties are good enough for high-resolution flat panel display application using carbon nanotube film arrays as the cathode. [ABSTRACT FROM AUTHOR]