Influence of preparation conditions on structure and photosensing properties of GeSi/TiO2 multilayers

The photosensing properties related to the structure of GeSi/TiO2 multilayers prepared under different conditions are studied. TiO
₂
cap/(GeSi/TiO
₂
)
₂
multilayers (ML) were deposited by magnetron sputtering (MS) and annealed by rapid thermal annealing. Trilayers of TiO
₂
cap/GeSi/TiO
₂
(TL) were also deposited using reactive high power impulse MS (HiPIMS) for TiO
₂
layers and dc MS for the GeSi layer. For TL samples a two-step annealing was employed, one before and the second after depositing TiO
₂
cap. Structure and morphology characterization (X-ray diffraction, scanning and transmission electron microscopy) was carried out and photocurrent measurements (voltage dependences, spectral curves) were performed. The annealed ML samples are formed of GeSi NCs with 5-10 nm sizes, while in the annealed TL samples, the GeSi NCs are larger (20-30 nm). These morphologies determine the multilayers photosensing properties in VIS-NIR of ML structures and in UV in TL ones, respectively.