Impact of Al Doping on Surface Passivation of TiOx on Si

Titania (TiO x ) is re-emerging to be a passivating material for the surfaces of high-efficiency crystalline silicon solar cells. Numerous sources in the literature suggest that the surface passivation and thermal stability of TiO x deteriorates with increasing film thickness when the TiO x film is thicker than a sufficient thickness. To circumvent this limitation, this study presents a novel process of Al-doped TiO x (TiO x :Al) film, which demonstrates the potential for improved thermal stability and surface passivation. Based on grazing incident X-ray diffraction and UV-Raman measurements, the incorporation of Al impurity in TiO x effectively restrains the crystal phase transformation of the amorphous TiO x layer during deposition. Furthermore, the TiO x :Al films provide better thermal robustness up to 350 °C, which makes it highly compatible with Si solar cell fabrication processes.