Abderrazak Guettaf

Correlation between electrical conductivity—optical band gap energy and precursor molarities ultrasonic spray deposition of ZnO thin films

ZnO thin films were deposited using the simple, flexible and cost-effective spray ultrasonic technique at different precursor molarities values. The films were deposited on a glass substrate at 350 °C. This paper is to present a new approach to the description of correlation between electrical conductivity and optical gap energy with precursor molarity of ZnO thin films. The ZnO films exhibit higher electrical n-type semiconductors, whose band gap energy increased from 3.08 to 3.37 eV with an increasing of precursor molarity of 0.05 to 0.1 M. The maximum value of electrical conductivity of the films is 7.96 (ωcm)−1 obtained in the ZnO thin film for precursor molarity 0.125 M. The correlation between the electrical and the optical properties with the precursor molarity suggests that the electrical conductivity of the films is predominantly influenced by the band gap energy and the precursor molarity. The measurement of the electrical conductivity of the films with correlation is equal to the experimental with the error is about 1% in the higher conductivity.

Correlation between crystallite size-optical gap energy and precursor molarities of ZnO thin films

We investigated the structural and optical properties of ZnO thin films as an n-type semiconductor. The films were deposited at different precursor molarities using an ultrasonic spray method. In this paper we focused our attention on a new approach describing a correlation between the crystallite size and optical gap energy with the precursor molarity of ZnO thin films. The results show that the X-ray diffraction (XRD) spectra revealed a preferred orientation of the crystallites along the c-axis. The maximum value of the crystallite size of the films is 63.99 nm obtained at 0.1 M. The films deposited with 0.1 M show lower absorption within the visible wavelength region. The optical gap energy increased from 3.08 to 3.37 eV with increasing precursor molarity of 0.05 to 0.1 M. The correlation between the structural and optical properties with the precursor molarity suggests that the crystallite size of the films is predominantly influenced by the band gap energy and the precursor molarity. The measurement of the crystallite size by the model proposed is equal to the experimental data. The minimum error value was estimated by Eq. (4) in the higher crystallinity.

Study on the correlation between crystallite size and optical gap energy of doped ZnO thin film

In the present paper, we have studied a new approach to the description ofcorrelation between the optical and structural properties of ZnO thin films withdoping levels of Al, Co, and In. The doped zinc oxide thin films were depositedusing ultrasonic spray technique on a glass substrate at 350°C. Thecorrelation between structural and optical properties with doping level suggeststhat the crystallite size of the films is predominantly estimated by the bandgapenergy and the concentration of Al, Co, and In. Also, the gap energy of dopedfilms was estimated by the crystallite size and doping level. The measurement inthe crystallite size and optical gap energy of doped films with correlation isequal to the experimental data. The minimum error value was estimated in dopedZnO thin films with indium and cobalt. Thus, results indicate that such Co-dopedZnO thin films are chemically purer and have many fewer defects and lessdisorder, owing to an almost complete chemical decomposition.

Backgating effect in GaAs FETs with a channel—semi-insulating substrate boundary

This study focuses on modeling the effects of deep hole traps, mainly the effect of the substrate (backgating effect) in a GaAs transistor MESFT. This effect is explained by the existence, at the interface, of a space charge zone. Any modulation in this area leads to response levels trapping the holes therein to the operating temperature. We subsequently developed a model treating the channel substrate interface as an N—P junction, allowing us to deduce the time dependence of the component parameters of the total resistance Rds, the pinch-off voltage VP, channel resistance, fully open Rco and the parasitic series resistance RS to bind the effect trap holes H1 and H0. When compared with the experimental results, the values of the RDS (tS) model for both traps show that there is an agreement between theory and experiment; it has inferred parameter traps, namely the density and the time constant of the trap. This means that a space charge region exists at the channel—substrate interface and that the properties can be approximated to an N—P junction.