Nanostructured device based on coated ZnO layer as a window in solar cell applications

Abstract

This work highlights some physical properties related to the influence of aluminum, tin and copper incorporation on nanostructured zinc oxide (ZnO:M; M:Al, Sn and Cu) thin films prepared by ultrasonic spray pyrolysis technique (USP) on glass substrate at 350±5°C. For the as-grown layers, M-to Zn-ratio was fixed at 1.5 %. The effects of metal doping on structural, morphological, optical and electrical properties were investigated. X-ray diffraction pattern revealed that the as-prepared thin films crystallized in hexagonal structure with (0 0 2) preferred orientation. The surface topography of the films was performed by atomic force microscopy. AFM images revealed inhibition of grain growth due to the doping elements incorporation into ZnO matrix, which induced the formation of ZnO nanoparticles. Optical measurements showed a high transparency around 90 % in visible range. Some optical parameters, such as optical band gap, Urbach energy, refractive index, extinction coefficient and dielectric constant were studied in terms of doping element. Particularly, dispersion of refractive index was discussed in terms of both Cauchy and single oscillator model proposed by Wemple and DiDomenico. Cauchy parameters and single oscillator energy E 0 as well as dispersion energy E d were calculated. Finally, electrical properties were investigated by means of electrical conductivity and Hall effect measurements. The measurements confirmed n type conductivity of the prepared thin films and a good agreement between the resistivity values and the oxidation number of doping element. The main aim of this work was the selection of the best candidate for doping ZnO for optoelectronics applications. The comparative study of M doped ZnO (M:Al, Sn and Cu) was performed. High rectifying efficiency of the Al/n-ZnO/p-Si/Al device was achieved and non-ideal behavior was revealed with n > 4.

The relation between the average diameter of CNTs on Ni–Cu @ a‐C:H catalyst with the optical absorption edge and the optical dispersion parameters

“…By investigation of the transmittance and reflectance variations versus photon wavelength, we can estimate the optical band gaps of films. The reports shown that the variations of d T/ d λ and d R/ d λ exhibits peaks which their centres can be related to the gap energy 24 . The curves of d T/ d λ and (d R/ d λ ) versus wavelength were plotted Figures 7(A) and (B).…”

Elaboration of high-transparency ZnO thin films by ultrasonic spray pyrolysis with fast growth rate

“…transmission average value is in the [80-85]% range [7-9, 13, 21, 47] in the visible spectrum region with some works recently report transmittance as high as 95 % for layers of thickness below 30 nm elaborated using a custom made spray pyrolysis and CVD system [10] and 90% for ultrasonic spray pyrolysis elaborated layers [12]. An annealing step can increase the transmittance beyond 90 % as shown in [48].…”

“…Elaboration techniques used for the growth of ZnO thin films are mainly based on reactive sputtering [1,2], pulsed laser deposition [3,4], sol-gel [5], molecular beam epitaxy [6], and spray pyrolysis [7][8][9][10][11][12]. The improved technique of ultrasonic spray pyrolysis allows for a better control of the deposition compared to conventional pneumatic spray systems.…”

Influence of different Ni nanolayers thicknesses on single oscillator model parameters, optical band gap, and disordering energy in CNTs synthesized by Cu‐Ni @ a‐CH catalyst

“…In fact, for an ideal material, the transmission for wavelengths less than (E) is zero. 33 The real and imaginary parts of the dielectric constant σ 1 and σ 2 can be used to calculate spectral behavior of the optical conductivity according to the following relations 34,35 :…”