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.
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