Effect of the electric field in glow discharge plasma sheath on the optoelectronic properties of the AlxZn1-xO thin films

Abstract

In this paper, we present the effect of the electric field in Ar and N2 plasma sheath on the structural, optical, and electrical properties of the AlxZn1-xO (x = 0, 0.02) thin films. The thin films were prepared via the sol-gel method on glass substrates and then treated in the Ar and N2 plasma. The crystalline structure properties of the thin films were evaluated by the XRD spectra and scanning electron microscope images. The parameters measured for the thin film's crystalline structure were the average crystallite size, the lattice strain, and the dislocation density. The optoelectronic properties, such as the refractive index, optical band gap energy, Urbach energy, dispersion parameters, and third-order nonlinear susceptibility were calculated based on the UV–vis spectrophotometer spectra. Due to the plasma treatment variation in the structural and optoelectronic properties was observed. The electric field in the Ar plasma sheath is stronger than the N2 plasma, so the properties’ alteration in the Ar plasma was more remarkable than the N2 plasma. For example, the third-order nonlinear optical susceptibility was increased by about 69 % and 38 % for the ZnO/Ar and the ZnO/N2, respectively. The severity of these changes was higher in the Ar plasma compared to the N2 plasma for the ZnO thin film, compared to the Al0.02Zn0.98O thin film.