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Fundamental characteristics such as retention and read endurance of a ferroelectric gate field effect transistor (F-FET) memory with an intermediate electrode were investigated and reported. It was verified that the retention time of the new F-FET was longer than 98 h. By taking into account the leakage currents of both the ferroelectric capacitor C f and the MOSFET used for data writing (W-FET), we found that, for positive reading voltage, the leakage currents of the ferroelectric capacitor and the W-FET are unfavorable for the P r + state and the P r - state, respectively, in terms of read endurance. The overall read endurance is determined by a competition between the leakage currents of the C f and the W-FET. The drain-connected configuration (DCC) was effective to minimize the unexpected influence of the leakage current of the W-FET.

We present a calculation of terahertz (THz) radiation by coherent optical phonons in GaAs p-i-n diode structure under high electric fields. The ultrafast dynamics of photoexcited carriers is simulated by adopting a self-consistent ensemble Monte Carlo method. It is demonstrated that the coherent phonon oscillations emitting the THz radiation are excited resonantly by synchronization between the proper lattice oscillation and ultrafast transient of electronic polarization originating from a drift overshoot within the initial period of lattice vibration.