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.
REFERENCES
For PZT, the d33 piezoelectric constant is ∼50 pm/V and the polarization ∼75 μC/cm2 for a tetragonality of 1.0475 (out-of-plane lattice constant of 4.148 Å, in-plane lattice constant of 3.96 Å). For the asymmetric 7 V voltage sweeps between approximately −3 and 4 V, a piezoelectric deformation of 350 pm would therefore be expected. The resulting change in tetragonality of ∼0.2% should not significantly affect the effective polarization.
