  In this work we combine a Fin Field Effect Transistor (Fin-FET) characterised
by a high height to width aspect ratio with high-k dielectric materials to
study the optimized design for chemical-FETs to provide higher transconductance
(and thus a better signal to noise ratio), increased dynamic range and chemical
stability. We used pH sensing to verify the design. We explored the sensitivity
and response linearity of silicon dioxide, alumina and hafnium oxide as
dielectric materials sensing pH, and compared their chemical stability in
different acids. The high aspect ratio fin geometry of the sensor provides high
currents, as well as a planar conduction channel more reliable than traditional
silicon nanowires. The hafnium oxide Fin-FET configuration performed the best
delivering the most linear response both for the output and transfer
characteristics providing a wider dynamic range. Hafnium oxide also showed the
best chemical stability. Thus, we believe that the developed high aspect ratio
Fin-FETs/high-k dielectric system can offer the best compromise of performance
of FET-based sensors.
