Some features of localization of Al, Ga and In impurities in ZnO layers

Abstract

Reducing the cost of the materials and technologies used to form functional films is one of the most pressing issues in the rapidly developing transparent electronics industry. In this regard, ZnO-based films deposited by magnetron sputtering are of particular interest, being considered as a real alternative to more expensive indium oxide films when forming transparent electrodes in various optoelectronic applications. However, the choice of optimal film’s compositions and formation modes for each specific application is complicated by the lack of systematic comparative data on these systems obtained under identical conditions. In this work, ZnO films doped with Al, Ga, and In at a level of 1 to 20 at.% were obtained under identical conditions by the magnetron sputtering method. The dependence of the structure and electrical characteristics of ZnO films on the dopant content and deposition temperature was studied. It has been established that the key factors determining the behavior of an impurity in a ZnO matrix are its chemical activity, solubility in the matrix, the ionic radius of the impurity metal in a given coordination, and the electrical characteristics of additional oxide phases of the doping element formed at grain boundaries.

Keywords

• thin film
• magnetron sputtering
• transparent electrode
• zinc oxide
• doping
• carrier transport
• microstructure
• grain boundary