Inorganic
materials such as SiO
x
and
SiN
x
are commonly used as dielectric layers
in thin-film transistors (TFTs), but recent advancements in TFT devices,
such as inclusion in flexible electronics, require the development
of novel types of dielectric layers. In this study, CVD-deposited
poly(p-xylylene) (PPx)-based polymers were evaluated
as alternative dielectric layers. CVD-deposited PPx can produce thin,
conformal, and pinhole-free polymer layers on various surfaces, including
oxides and metals, without interfacial defects. Three types of commercial
polymers were successfully deposited on various substrates and exhibited
stable dielectric properties under frequency and voltage sweeps. Additionally,
TFTs with PPx as a dielectric material and an oxide semiconductor
exhibited excellent device performance; a mobility as high as 22.72
cm2/(V s), which is the highest value among organic gate
dielectric TFTs, to the best of our knowledge. Because of the low-temperature
deposition process and its unprecedented mechanical flexibility, TFTs
with CVD-deposited PPx were successfully fabricated on a flexible
plastic substrate, exhibiting excellent durability over 10000 bending
cycles. Finally, a custom-synthesized functionalized PPx was introduced
into top-gated TFTs, demonstrating the possibility for expanding this
concept to a wide range of chemistries with tunable gate dielectric
layers.