Achour Rahal

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 (Ωcm)−1 for 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.

Preparation of n-type semiconductor SnO2 thin films

We studied fluorine-doped tin oxide on a glass substrate at 350°C using an ultrasonic spray technique. Tin (II) chloride dehydrate, ammonium fluoride dehydrate, ethanol and NaOH were used as the starting material, dopant source, solvent and stabilizer, respectively. The SnO2 : F thin films were deposited at 350°C and a pending time of 60 and 90 s. The as-grown films exhibit a hexagonal wurtzite structure and have (101) orientation. The G = 31.82 nm value of the grain size is attained from SnO2 : F film grown at 90 s, and the transmittance is greater than 80% in the visible region. The optical gap energy is found to measure 4.05 eV for the film prepared at 90 s, and the increase in the electrical conductivity of the film with the temperature of the sample is up to a maximum value of 265.58 (Ωcm)−1, with the maximum activation energy value of the films being found to measure 22.85 meV, indicating that the films exhibit an n-type semiconducting nature.

Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

Undoped nickel oxide (NiO) thin films were deposited on 500°C heated glass substrates using spray pyrolysis method at (0.015–0.1 M) range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD) shows the formation of NiO under cubic structure with single diffraction peak along (111) plane at . When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

Caractérisations Structurale, Optique et Electrique des Couches Minces du SnO2, Non Dopé et Dopé au Lithium, Elaborées par Spray Ultrasonique

In this work, undoped and Li doped tin oxide thin films (SnO2 and Li: SnO2) were prepared by spray ultrasonic technique on ordinary heated, at 480 ° C, glass substrates during three minutes. The solution precursor was SnCl2 dissolved in methanol and for doping LiCl2 was added in the precursor solution. X-ray diffraction (XRD), UVVisible spectroscopy and four point prop were employed to investigate the structural, optical and electrical characteristics of the films before and after doping. XRD showed that the films were tetragonal routile casteriste with (110) and (211) as preferred orientation for undoped and Li doped SnO2 respectively. Grain seizes were found to be in 29-33nm average. UV-Visible spectrum revealed that the prepared SnO2 films have transmittance value laying between 60-95% in visible region and optical gap varied between 3.72 to 3.87 eV for the undoped to 5.0%wt Li doped one respectively. Thin film thickness was estimated to be 200nm for the all samples. From electrical characterisation it was found that sheet resistance increases from 600 to 8.3x10Ω/cm after doping with 5.0%wt Li concentration which lead to an decrease in conductivity of the films.