Comment on ‘Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir–Blodgett films’

Previous work on ultra-thin P(VDF-TrFE) Langmuir–Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work earlier reported argues against intrinsic switching. In this Comment we discuss two published papers and new experimental results that support a lack of intrinsic switching and point to the conclusion that the thickness dependence of the Langmuir–Blodgett films is due to the influence of the electrode interfaces.

Insights to emitter saturation current densities of boron implanted samples based on defects simulations

Emitter saturation current densities, Joe have been investigated with different boron implantation dose and annealing conditions. The higher thermal budgets used here are shown experimentally to improve Joe, implying more complete defect dissolution. Simulations show that significant degradation in Joe can be attributed to the presence of dislocation loops. In addition, in cases where dislocation loops have been annealed, high dose boron implantation still results in stable boron interstitial clusters, which contributes to Joe degradation.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

High charge density and mobility in poly(3-hexylthiophene) using a polarizable gate dielectric

Organic field-effect transistors (OFETs) typically exhibit either a high charge transport mobility or a high charge density. Here we demonstrate an OFET in which both the mobility and the charge density have high values of 0.1 cm2/V s and 28 mC/m2, respectively. The high charge density is induced by the ferroelectric polarization of the gate dielectric poly(vinylidene fluoride/trifluoroethylene). The high mobility is achieved in a regioregular poly(3-hexylthiophene) semiconductor using a transistor with a top-gate layout that inherently exhibits a smooth semiconductor–dielectric interface. The combination of high mobility and charge density yields a record conductance value for polymer-based FETs of 0.3 µS.

Origin of the drain current bistability in polymer ferroelectric field-effect transistors

The authors present measurements that elucidate the mechanism behind the observed drain current bistability in ferroelectric field-effect transistors based on the ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) as the gate dielectric. Capacitance-voltage measurements on metal-insulator-semiconductor diodes demonstrate that the bistability originates from switching between two states in which the ferroelectric gate dielectric is either polarized or depolarized. Pulsed charge displacement measurements on these diodes enable a direct measurement of the accumulated charge in the polarized state of 40±3 mC/m2.

All-polymer ferroelectric transistors

We demonstrate thin-film ferroelectric transistors, made entirely from organic materials that are processed from solution. The devices consist of thin ferroelectric poly(vinylidene fluoride/trifluoroethylene) films sandwiched between electrodes made of conducting poly(3,4-ethylenedioxythiophene) stabilized with polystyrene-4-sulphonic acid. On top of this stack, an organic semiconductor is applied. The ferroelectric transistors, constructed using unipolar p- or n-type semiconductor channels, have remnant current modulations of ~10e3 with a retention time of hours. They can be switched in 0.1–1 ms at operating voltages less than 10 V.