Vertical Oxide Homojunction TFTs of 0.8 V Gated by $ \hbox{H}_{3}\hbox{PO}_{4}$-Treated $\hbox{SiO}_{2}$ Nanogranular Dielectric

Inorganic solid-state electrolyte film based on H
₃
PO
₄
-treated nanogranular SiO
₂
with high specific capacitance (8 μF/cm
²
) is developed for vertical indium-tin-oxide (ITO) homojunction thin-film transistors (TFTs) fabrication. Such proton conductor reduces the operating voltage of the vertical homojunction TFTs to 0.8 V due to the enhanced electric-double-layer capacitance. Vertical ITO TFTs gated by such dielectric exhibit a good performance, such as a high current output (> 10 Ma/cm
²
) a small subthreshold swing (<; 80 mV/dec), a good ohmic contact, and a large on-off ratio ( ~10
⁶
). These low-voltage TFTs are very promising for next-generation battery-powered portable sensors.