Comparison of multiple-polysilicon-nanowire pH-sensors coated with different ALD-deposited high-k dielectric materials

Multiple poly-silicon nanowires (PS-NW's) coated with different high-k dielectric materials, HfO₂, Al₂O₃, and TiO₂, were fabricated and their pH sensing characteristics were compared. Sidewall spacer formation technique was used for the PS-NW's fabrication and all the high-k materials were deposited by atomic-layer-deposition (ALD). Following the high-k dielectric deposition, a 3-aminopropyltriethoxysilane (y-APTES) layer was coated as sensing membrane. It is found that the multiple PS-NW sensor coated with HfO₂ exhibits the highest sensitivity and best reproducibility for pH sensing.