Improvement of the Properties of Direct-Current Magnetron-Sputtered Al-Doped ZnO Polycrystalline Films Containing Retained Ar Atoms Using 10-nm-Thick Buffer Layers

The use of a 10-nm-thick buffer layer enabled tailoring of the characteristics, such as film deposition and structural and electrical properties, of magnetron-sputtered Al-doped ZnO (AZO) films containing unintentionally retained Ar atoms. The AZO films were deposited on glass substrates coated with the buffer layer via direct-current magnetron sputtering using Ar gas, a substrate temperature of 200 degrees C, and sintered AZO targets with an Al2O3 content of 2.0 wt %. The use of a Ga-doped ZnO film possessing a texture with a specific well-defined orientation as the buffer layer was very effective for improving the crystallographic orientation, reducing the residual stress, and improving the carrier transport of the AZO films. The residual compressive stress and in-grain carrier mobility were responsible for the retention of Ar atoms by the films, as observed using an electron probe microanalyzer.