Ga-doped ZnO and (Ga?+?Al) co-doped ZnO thin films were deposited on glass substrates by radio frequency magnetron sputtering for three distances d between a substrate–target. The influence of the distance between substrate–target upon structure, microstructure, vibrational properties, and optical band gap of the thin films was analyzed by X-ray diffraction, atomic force microscopy (AFM), Raman spectroscopy, and optical transmission measurements. The diffraction patterns revealed that the ZnO film crystallites are preferentially oriented with the (002) planes parallel to the substrate surface. AFM images show a smooth and uniform surface as well as a high compact structure. The Raman results reveal that the co-doping with Al?+?Ga introduces 2B1(low) band and leads to the increase of intensity for longitudinal-optic’s band. In the visible region, the average value of the transmittance was above 80%. 相似文献
Rough surface develops through computer simulation by competition between growth mechanism random deposition (RD) with a probability of occurrence p and growth mechanism random deposition with surface relaxation (RDSR) with a probability of occurrence 1 − p, on L × L square plane for system size L to record the statistical average of time variation of surface roughness W(L, t) and average height H(t) for the model for specific values of L and p. Other than the pure RD model, the entire evolution may be divided into three regions separated by two specific cross-over times tx and tsat. The value of interface width at saturation Wsat depends on both L and p. The first growth exponent β1 increases exponentially with an increase in p and does not depend on L. The values of the second growth exponent β2, roughness exponent α, dynamic exponent z( = α/β2 ), and α + z are 0.0234 ± 0.0008, 0.0506 ± 0.0065, 2.1577 ± 0.0073, and 2.2083 ± 0.0138 respectively and they show no dependence on L and p values. Value of the first cross-over time tx increases exponentially with an increase in p and does not depend on L. Value of the second cross-over time tsat increases with an increase in both p and L values. The average growth velocity is unity for the model and is independent of both L and p. For the model, the growth velocity is unity and the fractional porosity is zero. The scaling exponents show some deviation from the relevant universality classes and depend on competitive growth probability for this model. No finite-size effect is present in the model. 相似文献
Novel multilayer thin films that consist solely of cross‐linked single component layers are generated by a selective cross‐linking of the poly(vinyl amine) (PVAm) layers in [PVAm/poly(acrylic acid) (PAA)]n thin films constructed either on silica particles or silicon wafers, followed by the removal of PAA. The surface topography of the (PVAm)n multilayer thin films, before and after the adsorption of human serum albumin (HSA), has been studied by atomic force microscopy on the freeze‐dried films. The decrease of the average roughness of the film after the adsorption of HSA showed the protein was adsorbed into the (PVAm)n film making these films potential reservoirs for proteins.
Organic field‐effect transistors incorporating planar π‐conjugated metal‐free macrocycles and their metal derivatives are fabricated by vacuum deposition. The crystal structures of [H2(OX)] (H2OX=etioporphyrin‐I), [Cu(OX)], [Pt(OX)], and [Pt(TBP)] (H2TBP=tetra‐(n‐butyl)porphyrin) as determined by single crystal X‐ray diffraction (XRD), reveal the absence of occluded solvent molecules. The field‐effect transistors (FETs) made from thin films of all these metal‐free macrocycles and their metal derivatives show a p‐type semiconductor behavior with a charge mobility (μ) ranging from 10?6 to 10?1 cm2 V?1 s?1. Annealing the as‐deposited Pt(OX) film leads to the formation of a polycrystalline film that exhibits excellent overall charge transport properties with a charge mobility of up to 3.2×10?1 cm2 V?1 s?1, which is the best value reported for a metalloporphyrin. Compared with their metal derivatives, the field‐effect transistors made from thin films of metal‐free macrocycles (except tetra‐(n‐propyl)porphycene) have significantly lower μ values (3.0×10?6–3.7×10?5 cm2 V?1 s?1). 相似文献
We introduce slope analysis as a straightforward complement to scaling analysis for characterizing the morphology of electrodeposited thin films. The surface slope θ, defined as the angle between the local surface normal and the film normal, is calculated as a function of position for electrodeposited Cu films of increasing thickness t. We show that the mean value of θ increases with t and demonstrate the close relationship between this observation and the increase in local roughness found in previous studies from scaling analysis. 相似文献
The single crystal of a silver complex bis (imidazole) silver(I) nitrate (Ag(C3H4N2)2(NO3), BISN) has been obtained and characterized by X‐ray single‐crystal diffraction. Its crystal thin film was prepared using direct growth on quartz substrates. The surface morphology of the thin film was studied by atomic force microscopy (AFM). The nonlinear optical (NLO) properties of the thin film were investigated by using closed‐aperture Z‐scan technique with 20 picosecond (ps) pulses at wavelength 532 nm. Using time‐dependent density‐functional theory (TDDFT) with the basis set LanL2DZ, its linear and NLO properties were calculated. 相似文献
Observation of Newton black film (NBF) in foam film is possible only with a certain probability W which depends on the concentration C of surfactant in the solution and on the time ta during which adsorption of surfactant at the solution/air interface has taken place. In the paper, the W(C,ta) dependence is derived and used to analyze the effect of ta on the critical surfactant concentration Cc below which NBF in foam film practically cannot be observed. An expression for the Cc(ta) function is obtained which reveals that Cc decreases substantially with increasing ta. This expression is found to describe well experimental Cc(ta) data for foam films obtained from aqueous solution of the therapeutic surfactant INFASURF. 相似文献
CuBiSe2 (CBSe) thin film was prepared by vacuum evaporation. The deposited film was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X‐ray (EDX), UV–visible specroscopy, and I–V analysis. XRD analysis indicates the formation of cubic CBSe thin film, and the corresponding EDX spectrum confirms the stoichiometry composition of CBSe. In the AFM images, the majority of the particles are granular, and the surface roughness is 8.86 nm. The optical absorption coefficient is >104 in the visible region and the bandgap energy is calculated to be 1.84 eV. The photosensitivity of the film is 181%. 相似文献
V5Al8 films (thickness about 100 nm) were deposited on sapphire substrates by RF‐sputtering and nitridated with NH3 at 600‐1250 °C (1 min) in a RTP system. The as deposited and nitridated films were investigated by ESCA (electron spectroscopy for chemical analysis), XRD (X‐ray diffraction), XRR (X‐ray reflectometry), AFM (atomic force microscopy) and SEM (scanning electron microscopy). Formation of an aluminum nitride layer at the surface and precipitation of V(Al) in the bulk was found. In the temperature regime from 600 °C to 900 °C a considerable amount of oxygen is incorporated in the aluminum nitride layer. The roughness of the surface increased with increasing temperature and at 1250 °C a partially detaching of the AlN layer could be observed. 相似文献