A dynamic ferroelectric capacitance model for circuit simulators
A dynamic model has been developed that is based on the Preisach approach for ferroelectric capacitors. It accounts for different switching reaction of the dipoles dependent on the applied voltage gradients. A method for extracting the necessary parameters by measuring the coercive voltage versus applied frequency is provided. The model was verified by testing capacitors of different geometries. Excellent agreement was achieved between our measurements and the corresponding circuit simulations. The simulation of a FeRAM-cell with our new dynamic model shows that the bit line signal decreases substantially with fast read/write times.
SrBi/sub 2/TaO/sub 9/ thin film capacitor model including polarization reversal response for nanosecond range circuit simulation of ferroelectric nonvolatile memory
An SrBi/sub 2/Ta/sub 2/O/sub 9/ thin film capacitor model including polarization reversal response based on P-t curves is proposed for the nanosecond range circuit simulations of ferroelectric nonvolatile memories (NVFRAMs). The circuit simulation for the READ/WRITE operation of the NVFRAM is realized by the capacitor model and it's unique parameter extraction method. This approach provides a significant means for predicting the READ/WRITE operations of the NVFRAMs in the range from 10 ns to 1 /spl mu/s.
General expression for the density effect for the ionization loss of charged particles
The equations for the density-effect correction $\ensuremath{\delta}(X)$ for the ionization loss as given in a previous paper have been extended to the case where $\ensuremath{\delta}({X}_{0})\ensuremath{\equiv}{\ensuremath{\delta}}_{0}g0$. Here ${X}_{0}$ is the lower limit of the range ${X}_{0}lXl{X}_{1}$, where a particularly simple expression for $\ensuremath{\delta}(X)$ applies; $X={log}_{10}(\frac{p}{{m}_{0}c})$, where $p$ is the momentum and ${m}_{0}$ is the mass of the incident particle. The case ${\ensuremath{\delta}}_{0}g0$ applies directly to the calculation of $\ensuremath{\delta}(X)$ for conductors (metals).