Reduction and uniformization of the resistivity of Ga-doped ZnO by combining short-gap magnetron sputtering and buffer layer

Abstract

To obtain low-resistance metal-doped ZnO film with a uniform resistivity distribution, a combination of short-gap magnetron sputtering and a buffer layer is proposed. The influence of the distance between the target and the substrate (T-S distance) on properties such as the thickness, resistivity, carrier density, carrier mobility, and crystallinity of Ga-doped ZnO thin films deposited by conventional RF planar magnetron sputtering was investigated. As the T-S distance decreased, the film resistivity remarkably decreased. Although spontaneous annealing greatly reduced the film's resistivity, the opposing part of the target erosion area showed high resistivity, possibly due to the bombardment of oxygen negative ions. The spatial uniformity in resistivity was greatly improved using a glass substrate on which a solid-phase-crystallized thin buffer layer was formed.