The study of structural and electrical properties of thin antimony films

Structural and electrical properties of thin antimony films of various thicknesses evaporated on to glass substrates have been studied in the temperature range 150 to 350 K. The structural studies show that the films are polycrystalline having grains whose size increases with thickness. The electrical resistivity is found to increase as thickness decreases, thus exhibiting the size effect. The effect of grain-boundary scattering has been studied using a Mayadas-Shatzkes model and a three-dimensional model. The experimental results on the electrical resistivity are found to be consistent with the three-dimensional model. The specularity parameterp 0.49, and has no temperature dependence. The values of reflection coefficient,R, and transmission coefficient,t, are determined from the experimental data.     

Electrical resistivity of thin bismuth films

The thickness dependence of electrical resistivity of thin bismuth films deposited on to glass substrates has been studied in the temperature range 77 to 350 K. The structural studies show that films are polycrystalline with grain size increasing with thickness. The electrical resistivity decreases with increasing temperature. This type of temperature dependence of electrical resistivity arises due to the competition between the temperature dependences of carrier density and carrier mobility, the temperature coefficients of which are opposite in sign. The electrical properties of bismuth films are greatly affected by the presence of surface states. The size effect theory of Pichard and colleagues (PTT) has been modified to investigate the variation of charge carrier concentration with thickness. The experimental results on electrical resistivity are found to be consistent with the predictions of this modified three-dimensional model (PTT). The value of specularity parameter,p, is about 0.43 and it exhibits no temperature dependence. The experimental results on grain-boundary resistivity agree fairly well with the theoretical variations. The values of transmission coefficient,t, are determined from the experimental data.     

Transport properties of vacuum deposited tin-tellurium alloy films

The transport properties of Sn_1?xTe_x (0相似文献   

Thin polycrystalline metallic-film conductivity under the assumption of isotropic grain-boundary scattering

The polycrystalline thin-film resistivity and its temperature coefficient of resistivity are calculated from the assumption of isotropic grain-boundary scattering. The proposed simple analytical equations allow separate determination of the transmission coefficient of the grain boundary and the specular reflection coefficient at external surfaces. Good agreement with experiment is found.     

Crystal structures and electrical properties of titanium films evaporated in high vacuum

Thin titanium films were deposited on glass substrates maintained at various elevated temperatures. X-ray studies showed that higher substrate temperatures caused growth of the $\text{{10}\text{1}\text{1}}$ orientation in preference to the {0002} orientation and also increased the grain size in the films. The dependences of the electrical resistivity and the Hall coefficient on the substrate temperature were investigated: the variation of the resistivity with substrate temperature can be explained qualitatively in terms of the grain sizes of the films, but the main feature of the Hall coefficient was found to be closely related to the differences in preferred orientation of the crystals.     

Effect of grain-boundary scattering on the electrical resistivity of indium films

Electrical resistivity and temperature coefficient of resistivity of polycrystalline indium films have been studied in the temperature range 30 to 90 C. It has been observed that the grain-boundary scattering theory of Mayadas and Shatzkes reproduces the experimental observations more faithfully than the size-effect theory given by Fuchs.     

The Effect of Substrate Temperature on Magnetic and Electrical Properties of (CeO<Subscript>2</Subscript>)<Subscript>14</Subscript>Fe<Subscript>86</Subscript> Films

(CeO₂)₁₄Fe₈₆ films were fabricated by a radio frequency magnetron sputtering method at different substrate temperature. The results reveal that the films deposited at substrate temperature lower than 773 K exhibit a strong perpendicular anisotropy, and the correlated dynamic permeability spectrum measured over the frequency range of 0.5–7 GHz shows a high resonance frequency. The study on the relation R～T shows that the resistivity of the thin film has a minimum near room temperature and tends to saturation as the temperature approaches zero, exhibiting a behavior reminiscent of Kondo scattering. However, as the substrate temperature increases to 973 K, the films possess an in-plane anisotropy and lower H _c. The resistivity exhibits a transition from metal to insulator characterized by a maximum of resistivity at 220 K.     

Structural,optical, and electrical properties of flash-evaporated copper indium diselenide thin films

Copper indium diselenide (CuInSe₂) compound was synthesized by reacting its elemental components, i.e., copper, indium, and selenium, in stoichiometric proportions (i.e., 1:1:2 with 5% excess selenium) in an evacuated quartz ampoule. Structural and compositional characterization of synthesized pulverized material confirms the polycrystalline nature of tetragonal phase and stoichiometry. CuInSe₂ thin films were deposited on soda lime glass substrates kept at different temperatures (300–573 K) using flash evaporation technique. The effect of substrate temperature on structural, morphological, optical, and electrical properties of CuInSe₂ thin films were investigated using X-ray diffraction analysis (XRD), atomic force microscopy (AFM), optical measurements (transmission and reflection), and Hall effect characterization techniques. XRD analysis revealed that CuInSe₂ thin films deposited above 473 K exhibit (112) preferred orientation of grains. Transmission and reflectance measurements analysis suggests that CuInSe₂ thin films deposited at different substrate temperatures have high absorption coefficient (~10⁴ cm⁻¹) and optical energy band gap in the range 0.93–1.02 eV. Results of electrical characterization showed that CuInSe₂ thin films deposited at different substrate temperatures have p-type conductivity and hole mobility value in the range 19–136 cm²/Vs. Variation of energy band gap and resistivity of CuInSe₂ thin films deposited at 523 K with thickness was also studied. The temperature dependence of electrical conductivity measurements showed that CuInSe₂ film deposited at 523 K has an activation energy of ~30 meV.     

Substrate temperature dependent morphology and resistivity of pulsed laser deposited iridium oxide thin films

Iridium oxide (IrO₂) thin films were deposited on Si (100) substrates by means of pulsed laser deposition technique at various substrate (deposition) temperatures ranging from 250 to 500 °C. Effects of substrate temperature on the crystalline nature, morphology and electrical properties of the deposited films were analyzed by using X-ray diffraction, Raman spectroscopy, Scanning electron microscopy and four-point probe method. It was found that the above properties were strongly dependent on the substrate temperature. The as-deposited films at all substrate temperatures were polycrystalline tetragonal IrO₂ and the preferential growth orientation changed with the substrate temperature. IrO₂ films exhibited fairly homogeneous thickness and good adhesion with the substrate, the average feature size increases with the substrate temperature. The room-temperature resistivity of IrO₂ films decreased with the increase of substrate temperature and the minimum resistivity of (42 ± 6) μΩ cm was obtained at 500 °C. The resistivity of IrO₂ films correlated well with the corresponding film morphology changes.     

Size effects of polycrystalline tin films

The electrical properties of polycrystalline tin films evaporated onto a cooled quartz substrate were examined in situ and in vacuum. The relationship between internal size effect and annealing temperature was considered. It was found that the parameter * of grain-boundary scattering decreased as the annealing temperature was increased.     

Size-dependence of electrical resistivity of vacuum-evaporated antimony films

Electrical resistivity and temperature coefficient of resistivity of polycrystalline antimony films (400 to 2100 Å) have been measuredin situ. Coherent and reproducible films are obtained by evaporating antimony from a molybdenum boat onto a heated glass substrate (150° C) at a low deposition rate (2 to 4 Å sec^?1). Both expressions for resistivity given by Lucas and Fuchs seem to reproduce the experimental observation quite faithfully indicating partial specular scattering of electrons.     

Heat sensitive property of sputtered titanium oxide thin films for uncooled IR detector application

Titanium oxide (TiO_x) thin films were deposited on thermally grown Si₃N₄-film-coated Si substrates by dc reactive magnetron sputtering. The crystallographic structure, microscopic morphology, electrical resistivity, temperature coefficient of resistance (TCR) and activation energy of the films were proven as functions of the oxygen partial pressure (pO₂) and substrate temperature (T _s ). The mixed valence TiO_x thin films deposited with temperature from 30 to 250 °C in different pO₂ present various electrical properties even though all the samples are amorphous. The TCR and activation energy of the films vary with different pO₂ and T _s . It has been demonstrated that the sputtered TiO_x films are promising heat sensitive materials for uncooled Infrared detector application.     

Resistivity and temperature coefficient of resistivity of tin films

The electrical resistivity and the temperature coefficient of resistivity of tin films (490 to 5000 Å) deposited onto glass substrates at room temperature (30° C) were measured in situ in the temperature range 30 to 150° C. It is concluded that Mayadas-Shatzkes theory reproduces the experimental observations more faithfully than Fuchs-Sondheimer's theory.     

Influence of substrate temperature on crystalline copper aluminium oxide thin films synthesized through chemical spray pyrolysis (CSP) technique

Copper aluminium oxide (CuAlO₂) of well ordered crystalline films were deposited on to glass substrates with Cu/Al ratio r = 0.8 at the substrate temperatures of 250, 300, 350, 400 and 450 °C. Films which were characterized had a thickness of the order of few micrometers. Films deposited at the optimized deposition temperature (450 °C) revealed well-crystalline CuAlO₂ phase with XRD peak at 2θ = 31.7° corresponds to (006) reflection. The peak positions of the core level XPS spectra, confirm the presence of delafossite CuAlO₂ phase. The optical transmission of 80 % has been observed in the visible spectrum. The obtained band gap energy is 4.1 eV. From the observed results it was evidenced that the substrate temperature has strong influence on the structural and optical properties of the spray pyrolysed copper aluminium oxide films.     

Structural and electrical properties of RuO2 thin films prepared by rf-magnetron sputtering and annealing at different temperatures

Conductive ruthenium oxide (RuO₂) thin films have been deposited at different substrate temperatures on various substrates by radio-frequency (rf) magnetron sputtering and were later annealed at different temperatures. The thickness of the films ranges from 50 to 700 nm. Films deposited at higher temperatures show larger grain size (about 140 nm) with (200) preferred orientation. Films deposited at lower substrate temperature have smaller grains (about 55 nm) with (110) preferred orientation. The electrical resistivity decreases slightly with increasing film thickness but is more influenced by the deposition and annealing temperature. Maximum resistivity is 861 μΩ cm, observed for films deposited at room temperature on glass substrates. Minimum resistivity is 40 μΩ cm observed for a thin film (50 nm) deposited at 540°C on a quartz substrate. Micro-Raman investigations indicate that strain-free well-crystallized thin films are deposited on oxidized Si substrates.     

Electrical properties of ZnSe-CdS alloy films

Thin films of ZnSe _x CdS_1–x (t 0.6 m) over the entire range of x, were deposited on glass substrates at two temperatures, T _s (350 and 470 K) by vacuum evaporation. X-ray diffraction studies showed that all the films were polycrystalline in nature. Films prepared at 470 K were nearly stoichiometric. Grain size increased with substrate temperature, T _s. The electrical conductivity and Hall measurements were carried out by d.c. van der Pauw technique. Hall effect studies/hot probe test showed that all the films were of n-type conductivity. Hall mobility increased with T _s. In addition, mobilities increased with temperature in films of all compositions, indicating the dominance of grain-boundary scattering. Grain-boundary potentials were in range 0.03–0.06 eV.     

Characterization of Tin disulphide thin films prepared at different substrate temperature using spray pyrolysis technique

Thin films of tin disulphide on glass substrates were prepared by spray pyrolysis technique using precursor solutions of SnCl₂·2H₂O and n–n dimethyl thiourea at different substrate temperatures varied in the range 348–423 K. Using the hot probe technique the type of conductivity is found to be n type. X ray diffraction analysis revealed the polycrystalline nature with increasing crystallinity with respect to substrate temperature. The preferential orientation growth of SnS₂ compound having hexagonal structure along (002) plane increased with the substrate temperature. The size of the tin disulphide crystallites with nano dimension were determined using the Full Width Half Maximum values of the Bragg peaks and found to increase with the substrate temperature. The surface morphology had been observed on the surface of these films using scanning electron microscope. The optical absorption and transmittance spectra have been recorded for these films in the wavelength range 400–800 nm. Thickness of these films was found using surface roughness profilometer. The absorption coefficient (α) was determined for all the films. Direct band gap values were found to exist in all the films deposited at different substrate temperatures. The value of room temperature resistivity in dark decreased from 5.95 × 10³ Ω cm for the amorphous film deposited at low temperature (348 K) to 2.22 × 10³ Ω cm for the polycrystalline film deposited at high temperature (423 K) whereas the resistivity values in light decreased from 1.48 × 10³ to 0.55 × 10³ Ω cm respectively, which is determined using the four probe method. Activation energy of these thin films was determined by Arrhenius plot.     

The mechanical properties and resistivity of Au/NiCr/Ta multi-layered films on Si-(111) substrate

Au/NiCr/Ta multi-layered metallic films were deposited on Si substrate by magnetron sputtering at different substrate temperatures. The residual stress, hardness and resistivity were investigated as a function of substrate temperature by laser polarization phase shift technique, nanoindentation technique and four point probe method, respectively. The residual stress in as-deposited films at different substrate temperatures was tension with 385 MPa-606 MPa. Nanoindentation tests at shallow indentation depths (h ≤ t/4) where the hardness is reliable for metal films on hard substrate. Au film at deposition temperature 200 °C has the highest hardness 4.2 GPa. The resistivity in the deposited films reached the lowest value 3.1 μΩ.cm at substrate temperature 200 °C. The most interesting facts are that the hardness decreases with increasing residual stress and resistivity increases with increasing residual stress. The relationship of residual stress and resistivity may hint that there is a definite correlation between the mechanical properties and electrical properties in the metallic films.     

Resistivity and temperature coefficient of resistance of chromium-copper alloy films

Measurements of electrical resistivity and the temperature coefficient of resistance of vacuum deposited chromium—copper alloy films are reported. The mean freepath of the conduction electrons calculated from resistivity data and TCR data is 37.6 and 36.3 nm, respectively. The resistivity and TCR of an infinitely thick film have been computed to be 3.83 μΩcm and 2.886 × 10^?3° C^?1, respectively. The experimental data can be satisfactorily explained on the basis of Fuchs-Sondheimer theory assuming a total diffuse scattering.     

Deposition at low substrate temperatures of high-quality TiO2 films by radical beam-assisted evaporation

We deposited high-quality TiO(2) films by an oxygen-radical beam-assisted evaporation (RBE) method at a lower substrate temperature (Ts) than that for a TiO(2) film deposited by conventional thermal evaporation (TE) with neutral-oxygen gas. The films were then evaluated in terms of refractive index, shift of wavelength of a peak in the reflection curve, and absorption coefficient. The TiO(2) films deposited by RBE at Ts < 473 K showed higher refractive indices, were more compact, and had lower absorption coefficients than the film deposited by TE at Ts = 473 K.