Effect of y and Mn doping into rutile type TiO₂/Ge stack structure by combinatorial synthesis

The effects of Y and Mn doping into the rutile TiO₂ films on a (100) Ge substrate stack structure were investigated by combinatorial synthesis. Composition spread films were fabricated by combinatorial pulsed laser deposition. Regardless of the dopant concentration, the Mn-doped TiO₂ film indicated an amorphous structure. In contrast, the Y-doped TiO₂ film had a rutile-type crystal structure below an Y concentration of 11.0 at.%. The high Y concentration enhanced the amorphous structure and Ge diffusion into the TiO₂ layer. Although both dopants reduced leakage currents, the effect of Y was greater than that of Mn. The post-deposition annealed Y-doped TiO₂ indicated an improvement in the leakage current by three orders of magnitude and electron accumulation at a capacitor structure. The Y doping into TiO₂ may provide beneficial effects of good interface control and effective dielectric material for Ge-based capacitors.