C–V characteristics of Pt/PbZr0.53Ti0.47O3/LaAlO3/Si and Pt/PbZr0.53Ti0.47O3/La0.85Sr0.15CoO3/LaAlO3/Si structures for ferroelectric gate FET memory

Pt/PbZr0.53Ti0.47O3 (PZT)/LaAlO3 (LAO)/Si and Pt/PbZr0.53Ti0.47O3/La0.85Sr0.15CoO3 (LSCO)/LaAlO3/Si structures for ferroelectric field effect memory applications were fabricated on n-type Si substrate by pulsed laser deposition (PLD). The Auger electron spectrometry (AES) analysis shows that a LaAlO3 buffer layer can effectively prevent Si and Ti, Pb interdiffusion between PZT and Si substrate. For both of the structure, the current density–voltage measurement shows a typical leakage current density of about 10−7 A/cm2 at 8 V applied voltage. Furthermore, it has been demonstrated that the PbZr0.53Ti0.47O3/LaAlO3/Si structures and Pt/PbZr0.53Ti0.47O3/La0.85Sr0.15CoO3/LaAlO3/Si structures exhibit ferroelectric switching properties, showing a memory window as large as 2 and 2.9 V, respectively, under a ramp rate of 200 mV/s from −6 to +6 V driving voltage at 1 MHz. It is believed that the La0.85Sr0.15CoO3 buffer layer deposited on LaAlO3 layer can improve the crystalline properties of PZT films, and then result in lager polarization of PZT and lager memory windows for Pt/PbZr0.53Ti0.47O3/La0.85Sr0.15CoO3/LaAlO3/Si structures.