Investigation of Structural Electrophysical Parameters of ZnO al Films for Electronics

Abstract

In this paper, the effect of the introduction of aluminum in concentrations 1—3 at was investigated. % in semiconductor nanostructured zinc oxide films obtained by sol-gel method. Based on the results of scanning electron microscopy, it was found that all samples have a branched structure, while there is a tendency for the branches to enlarge with an increase in the concentration of the modifier. Studies of optical transmission spectra have shown that the samples are transparent in the visible radiation range; the calculation of the optical band gap showed an increase in the amorphization of the material, which we associate with the for-mation of impurity levels formed by aluminum cations overlapping with the band conductivity, as well as an increase in the concentration of intrinsic point electrically active defects. Analysis of the results of the dependence of electrical conductivity on temperature showed its semiconductor nature and the presence of two regions with the following activation energies: the first region is a low—temperature region with low energy in the range of 35—75 meV; the second region is a high—temperature region with energy in the range of 0.35— 0.45 eV. We associate the low activation energy with donor levels of interstitial zinc Zni defects. At the same time, with an increase in the concentration of aluminum, the value of the activation energy of this level decreases, which is associated with the substitution of zinc atoms with aluminum and their displacement into the internode. The analysis of the electrical conductivity of the studied films in the range of 20...400 °C shows its maximum value at the concentration of the alloying impurity in 1 at. %. Thus, this composition is optimal from the point of view of obtaining transparent conductive films.