Ar/N2 Magnetron Sputtering Discharges to Control Growth of Transparent Conducting Oxide Films

Here we demonstrate advantageous application of Ar/N2 discharges to magnetron sputtering deposition of ZnO films for crystal growth control [1]. Optical emission spectroscopy reveals that atomic nitrogen in Ar/N2 discharges plays important roles in determining the crystal grain density as well as the surface morphology of ZnO films. By utilizing 10-nm-thick ZnO films fabricated in Ar/N2 discharges as buffer layers, we have succeeded in fabricating low-resistive ZnO:Al (2wt.{\%}) films, the properties of which are superior to those of conventional ZnO:Al films fabricated without N2. The resistivity of ZnO:Al films with buffer layers is a constant low value of 2.6x10$^{-4}$ $\Omega \cdot$cm in the thickness range 20-200 nm, whereas the resistivity of conventional ZnO:Al films increases from 6.3x10$^{-4}$ to 1.5x10$^{-3}$ $\Omega \cdot$cm with decreasing the thickness from 200 nm to 20 nm. Effects of Ar/N2 discharges on other transparent conductive oxides including In2O3:Sn will be discussed at the conference.\\[4pt] [1] N. Itagaki, et al., Appl. Phys. Express 4 (2011) 011101.