Growth and properties of amorphous thin films of the Al2O3–Y2O3 system

Thin films of the aluminum oxide (Al2O3)-yttrium oxide (Y2O3) system including Al2O3, Y2O3, and mixed Al2O3–Y2O3 were prepared by radio-frequency magnetron sputtering using ceramic targets of Al2O3, Y2O3, and Al2O3–Y2O3 with different Y2O3 / (Al2O3 + Y2O3) molar ratios. These films were deposited at different substrate temperatures. The low-Y2O3 composite films had growth rate insensitive to deposition temperature, while a decreased rate at high temperature for the rest of films. The growth rates ranged 0.13–0.35 μm/h. Composition, growth morphology, dielectric properties, and electrical properties were investigated. The mixed-oxide films of the Al2O3–Y2O3 system had a varied dielectric constant of 8–13.5, a loss tangent of ∼0.05, leakage current density of ∼10− 6 A/cm2 at 80 kV/cm, and varied breakdown strength of 2.2–4.8 MV/cm, depending upon the Y2O3 amount. Point defects in pure Y2O3 films are the reason for degraded dielectric performance.