Electrical properties and crystalline defects of low-resistance Ga-doped ZnO films deposited by Zn-supplied sputtering deposition

Abstract To understand the mechanism of why the resistivity of Ga-doped ZnO (GZO) films decreases down to 4.3 × 10 −4 Ωcm without substrate heating by the sputtering method using Zn-added targets, the electrical and structural properties of ZnO and GZO films deposited under various conditions were investigated. The carrier density of ZnO films increased with Zn supply, indicating that the donor-like defects of Zn interstitials (Zn i ) were created. The increase in carrier density of GZO films by a Zn supply was much larger than that of ZnO films, and the Ga activity was enhanced for the films with high Ga content. These results indicate that the acceptor-like complex defects, such as Ga Zn -V Zn and/or Ga Zn -O i , were created in GZO films, and Zn supply reduced these defects. The relationship between carrier density and mobility indicated that Zn supply also reduced carrier scattering at grain boundaries.