  To optimize the performance of multifunctional carbon nanotube-ferroelectric
devices, it is necessary to understand both the polarization and charge
dynamics effects on their transconductance. Directly comparing ferroelectric
Pb(Zr0.2Ti0.8)O3 and dielectric SrTiO3 field effect transistors, we show that
the two effects strongly compete, with transient charge dynamics initially
masking up to 40% of the ferroelectric field effect. For applications, it is
therefore crucial to maximize the quality of the ferroelectric film and the
interface with the carbon nanotube to take full advantage of the switchable
polarization.
