The effect of the conditions of preparing thin zinc telluride films on their electrical properties

The results presented are of an investigation into the electrical properties of sublimated zinc telluride films of the cubic modification obtained under various conditions of production. The electrical resistivity and the thermo-emf were measured on test specimens at room temperature, and the sign of the current carriers was determined. The dependence of the resistivity on the specimen thickness, on the temperature of preliminary heating of the substrate on which the film was deposited, and on the evaporation temperature was studied. In addition the temperature dependence of the electrical conductivity of layers obtained under various conditions of deposition was investigated. It was established that the thermo-emf coefficient and the specific conductivity of zinc telluride films depend to a considerable extent on the conditions under which they were prepared. The differences that were found were attributed to a change in the stoichiometric composition of the test specimens.     

Plasma reflectivity of tin telluride epitaxial films

Infrared plasma reflectivity was measured at 300K for SnTe epitaxial films with hole concentrations in the range 4 × 10¹⁹ to 2.6 × 10²⁰/cm³. The concentration dependences of reflectivity minimum wavelength, hole susceptibility mass and relaxation time were determined. The susceptibility effective masses were compared with those expected for Kane, Cohen and ‘empirical’ models. This comparison shows that these simple models seem to be not suitable for SnTe.     

Measurement of properties of silver telluride thin films using holography

Holography is an interferometric method of recording the light waves diffracted by a subject illuminated with coherent light. Holographic interferometry (H.I.) is one of the most important applications of holography. It is concerned with the formation and interpretation of fringe patterns, which appears when a wave generated at some earlier time and stored in a hologram is later reconstructed by interfering with comparison wave. We report a technique, which uses double exposure holographic interferometry together with simple mathematical interpretation, which allow immediate finding of stress and thickness of thin film. We tested the same for different normalities of solutions. It was further noticed that the fringe spacing changes with solution concentration as well as time of deposition. The thin films are prepared using electrodeposition technique. It’s structural, morphological and optical study carried out by XRD, SEM, and UV-Vis-NIR spectrophotometer.     

Structural,optical and electrical properties of tin oxide thin films by electrostatic spray deposition

Tin oxide (SnO₂) thin films were deposited by electrostatic spray deposition (ESD). The structural, optical and electrical properties of the films for different solvents were studied. The morphology of the deposited thin films was investigated by scanning electron microscopy. The optical transmission spectra of the films showed 66–75% transmittance in the visible region of spectrum. The electrical resistivity of thin films deposited using the different solvents ranged 1.08 × 10^?3–1.34 × 10^?3 Ω-cm. Overall, EG and PG were good solvents for depositing SnO₂ thin films by the ESD technique with stable cone jet.     

The electrical properties of thin permalloy films

The magnetic properties of thin Permalloy films have been the subject of many investigations, but the work on their electrical properties is very limited [1]. By observing the change in electrical resistance with temperature the structural transformations taking place during the annealing of the condensates can be inferred.The authors of [1] did not undertake a detailed study of the electrical properties of Permalloy. They used Permalloy 79NMA in their investigation, and the dependence of the change in electrical resistance on the temperature of annealing in a magnetic field enabled them to reach conclusions about the nature of the uniaxial anisotropy of thin films.In the present work a detailed study has been made of the electrical resistance of Permalloy films in relation to the temperature of the substrate during evaporation and annealing; the temperature coefficient of resistance (TCR) has also been studied.     

Structural and optical properties of thermally evaporated antimony telluride thin films

Antimony telluride thin films were prepared on the well-cleaned glass substrates under a pressure of 10 – 5 torr by thermal evaporation method. The thicknesses of the films were measured using Multiple Beam Interferometer (MBI) technique. The structure of the sample was analyzed by X-ray diffraction technique. The film attains crystalline structure as the temperature of the substrate is increased to 373 K. The d spacing and the lattice parameters of the sample were calculated. Optical behavior of the film samples with the various thicknesses was analyzed by obtaining their transmittance spectra in the wavelength range of 400 – 800 nm. The transmittance is found to decrease with increase in film thickness and also it falls steeply with decreasing wavelength. The optical constants were estimated and the results are discussed. The optical band gap energy decreases with increase in the film thickness. The optical transition in these films is found to be indirect and allowed. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Structural,optical, and electrical properties of tin sulfide thin films grown with electron-beam evaporation

The effect of growth temperature on the phase evolution and morphology change of tin sulfide thin films by electron-beam evaporation was investigated. Orthorhombic tin monosulfide (SnS) was dominant at low growth temperature of 25 °C, whereas a sulfur-rich phase of Sn₂S₃ coalesced as the growth temperature increased over 200 °C. Thin film growth ceased at 280 °C due to re-evaporation of the tin sulfide. The dependence of growth temperature on the phase evolution of tin sulfide was confirmed by X-ray diffraction, scanning electron microscopy, and UV–Vis spectrophotometry. The lowest electrical resistivity of ∼51 Ω cm, with a majority hole concentration of ∼10¹⁷ cm⁻³, was obtained for the film grown at 100 °C, and the resistivity drastically increased with increasing growth temperature. This behavior was correlated with the emergence of resistive sulfur-rich Sn₂S₃ phase at high temperatures.     

Structural and electrical properties of fluorine-doped zinc tin oxide thin films prepared by radio-frequency magnetron sputtering

Transparent and conductive thin films of fluorine doped zinc tin oxide (FZTO) were deposited on glass substrates by radio-frequency (RF) magnetron sputtering using a 30 wt% ZnO with 70 wt% SnO₂ ceramic targets. The F-doping was carried out by introducing a mixed gas of pure Ar, CF₄, and O₂ forming gas into the sputtering chamber while sputtering ZTO target. The effect of annealing temperature on the structural, electrical and optical performances of FZTO thin films has been studied. FZTO thin film annealed at 600 °C shows the decrease in resistivity 5.47 × 10⁻³ Ω cm, carrier concentration ∼10¹⁹ cm⁻³, mobility ∼20 cm² V⁻¹ s⁻¹ and an increase in optical band gap from 3.41 to 3.60 eV with increasing the annealing temperatures which is well explained by Burstein–Moss effect. The optical transmittance of FZTO films was higher than 80% in all specimens. Work function (ϕ) of the FZTO films increase from 3.80 eV to 4.10 eV through annealing and are largely dependent on the amounts of incorporated F. FZTO is a possible potential transparent conducting oxide (TCO) alternative for application in optoelectronics.     

Electrochemically deposited bismuth telluride thin films

Thin films of bismuth telluride grown by electrochemical deposition technique on conducting glass and Mo sheet substrates, were characterized for their structural, morphological, optical and compositional analysis. These studies revealed polycrystalline anisotropic and layered structure of these films with different compositional stoichiometry. In the present work electrochemical deposition of bismuth telluride thin films is studied as a dopant material in II–VI group absorber materials for photovoltaic application since it has a narrow optical energy band gap of 0.13 eV. In this deposition process different film growth parameters were optimized to get good quality of compositionally uniform bismuth telluride thin film. XRD analysis revealed a hexagonal symmetry with large c-axis lattice constants (Bi₂Te₃, Bi_2+XTe_3−X).     

Tuning the properties of tin oxide thin films for device fabrications

Tin oxide thin films were deposited on well cleaned glass substrates by thermal evaporation in vacuum and were annealed at 500?^°C in the open atmosphere inside a furnace for 90 min for promoting the sensitivity of the films. The X-ray diffraction studies revealed that the as-deposited films were amorphous in nature and the annealed films showed appreciable crystalline behavior. The annealed thin films were then irradiated using ⁶⁰Co gamma source. The radiation induced changes were then studied by X-ray diffraction, scanning electron microscopy, UV–vis spectroscopy and I–V characterization. The remarkable increase in the average grain size, the decrement in the energy band gap and resistivity due to the gamma irradiations up to a certain dose and the reversal of these properties at higher doses are the important observations. The large changes in the conductivity and energy band gap of the annealed thin films due to gamma irradiation make these films quite important device material for the fabrication of gamma sensors and dosimeters.     

Optical and electrical properties of InGaZnON thin films

The substrate temperature(T_s)and N_2 partial pressure(P_(N2))dependent optical and electrical properties of sputtered InGaZnON thin films are studied.With the increased T_s and P_(N2),the thin film becomes more crystallized and nitrified.The Hall mobility,free carrier concentration(Ne),and electrical conductivity increase with the lowered interfacial potential barrier during crystal growing.The photoluminescence(PL)intensity decreases with the increased Ne.The band gap(Eg)narrows and the linear refractive index(n1)increases with the increasing concentration of N in the thin films.The Stokes shift between the PL peak and absorption edge decreases with Eg.The n1,dispersion energy,average oscillator wavelength,and oscillator length strength all increase with n1.The single oscillator energy decreases with n1.The nonlinear refractive index and third order optical susceptibility increase with n1.The Seebeck coefficient,electron effective mass,mean free path,scattering time,and plasma energy are all Ne dependent.     

Microstructure and electrical properties of SnS thin films

Thin SnS films are of interest for optoelectronics. The influence of the preparation modes on the microstructure and electrical properties of thin SnS films obtained by the hot-wall method on substrates made of pure glass and glass with a molybdenum sublayer has been investigated. It has been established that the formation of SnS films with two texture types (111) and (010) is possible on the substrates made of pure glass, depending on the mode. The resistivity and the temperature coefficient of thermoelectric power of the SnS films on glass vary in the range from 12 to 817 Ω cm and from 37 to 597 μV/K, respectively, depending on the preparation modes. The activation energy is 0.11–0.12 eV.     

Enhanced electrical properties in bilayered ferroelectric thin films

Sr2Bi4Ti5O18(SBTi) single layered and Sr2Bi4Ti5O18 /Pb(Zr0.53Ti0.47)O3(SBTi/PZT) bilayered thin films have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed-laser deposition(PLD).The related structural characterizations and electrical properties have been comparatively investigated.X-ray diffraction reveals that both films have crystallized into perovskite phases and scanning electron microscopy shows the sharp interfaces.Both films show well-saturated ferroelectric hysteresis loops,however,compared with the single layered SBTi films,the SBTi/PZT bilayered films have significantly increased remnant polarization(Pr) and decreased coercive field(Ec),with the applied field of 260 kV/cm.The measured Pr and Ec of SBTi and SBTi/PZT films were 7.9 C/cm 2,88.1 kV/cm and 13.0 C/cm 2,51.2 kV/cm,respectively.In addition,both films showed good fatigue-free characteristics,the switchable polarization decreased by 9% and 11% of the initial values after 2.2 10 9 switching cycles for the SBTi single layered films and the SBTi/PZT bilayered films,respectively.Our results may provide some guidelines for further optimization of multilayered ferroelectric thin films.     

Optical properties of cuprous telluride films

The structure of vacuum-deposited cuprous telluride Cu₂Te films deposited on carbon substrates was observed by means of an electron microscope. Films on glass substrates were also investigated by X-ray diffraction. The optical constants (the refractive index n and the extinction coefficient k) of Cu₂Te thin films were determined from the measured transmittance and reflectance at normal incidence of light in the wavelength range 0.4 m to 2.5 m. The variation of the optical constants with thickness for different evaporated films have been determined.     

Structural and electrical properties of evaporated Fe thin films

Series of Fe thin films have been prepared by thermal evaporation onto glass and Si(1 0 0) substrates. The Rutherford backscattering (RBS), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and the four point probe techniques have been used to investigate the structural and electrical properties of these Fe thin films as a function of the substrate, the Fe thickness t in the 76-431 nm range and the deposition rate. The Fe/Si samples have a 〈1 1 0〉 for all thicknesses, whereas the Fe/glass grows with a strong 〈1 0 0〉 texture; as t increases (>100 nm), the preferred orientation changes to 〈1 1 0〉. The compressive stress in Fe/Si remains constant over the whole thickness range and is greater than the one in Fe/glass which is relieved when t > 100 nm. The grain size D values are between 9.2 and 30 nm. The Fe/glass films are more electrically resistive than the Fe/Si(1 0 0) ones. Diffusion at the grain boundary seems to be the predominant factor in the electrical resistivity ρ values with the reflection coefficient R greater in Fe/glass than in Fe/Si. For the same thickness (100 nm), the decrease of the deposition rate from 4.3 to 0.3 Å/s did not affect the texture and the reflection coefficient R but led to an increase in D and a decrease in the strain and in ρ for both Fe/glass and Fe/Si systems. On the other hand, keeping the same deposition rate (0.3 Å/s) and increasing the thickness t from 76 to 100 nm induced different changes in the two systems.     

Structure and electrical properties of thin films of copper selenide

Electron-diffraction and electron-microscope methods were used to investigate the structure of Cu₂Se films of close to stoichiometric composition. It is shown that in polycrystalline and single-crystal films of thickness >400Å at room temperature, the tetragonal modification is stable, which at temperatures above 400°K is transformed into the cubical modification. In thinner films d<400 Å the cubical modification of copper selenide is stable at room temperature. A sharp peak is observed at 400°K on the temperature dependence of the resistance; this is connected with the phase transition. At room temperature, copper selenide is a degenerate p-type semiconductor with carrier concentration 5 · 10²²–8 · 10²⁰ cm^–3, depending on the thickness of the film.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 90–94, August, 1973.     

Optical and electrical properties of thermally oxidized bismuth thin films

Bismuth trioxide (Bi₂O₃) thin films were prepared by dry thermal oxidation of metallic bismuth films deposited by vacuum evaporation. The oxidation process of Bi films consists of a heating from the room temperature to an oxidation temperature (T_o = 673 K), with a temperature rate of 8 K/min; an annealing for 1 h at oxidation temperature and, finally, a cooling to room temperature. The optical transmission and reflection spectra of the films were studied in spectral domains ranged between 300 nm and 1700 nm, for the transmission coefficient, and between 380 nm and 1050 nm for the reflection coefficient, respectively. The thin-film surface structures of the metal/oxide/metal type were used for the study of the static current-voltage (I-U) characteristics. The temperature of the substrate during bismuth deposition strongly influences both the optical and the electrical properties of the oxidized films. For lower values of intensity of electric field (ξ < 5 × 10⁴V/cm), I-U characteristics are ohmic.