Characteristics of Pt/SrBi2Ta2O9/Y2O3/Si ferroelectric gate capacitors

Abstract

We have fabricated metal/ferroelectric/insulator/semiconductor (MEFIS) capacitors using Pt, SrBi2Ta2O9 (SBT), and Y2O3 thin films. As a buffer layer between the ferroelectric and the Si substrate, a Y2O3 film is rf-sputtered on the Si substrate and crystallized along the [111] direction during the annealing process. The dielectric constant and the interface trap charge density of the Y2O3 film are about 9 and 2x10(11) eV(-1).cm(-2), respectively. The SET thin films deposited on both Si(100) and Y2O3(222)/Si(100) by using metal organic deposition (MOD) show similar diffraction patterns with randomly oriented polycrystalline phases. The MEFIS capacitors show good ferroelectric hysteresis arising from the polarization switching properties. The memory window in the capacitance-voltage (C-V) curve and the leakage-current density of Pt/SBT(180 nm)/Y2O3(16 nm)/SiO2(4 nm)/Si are 3.08 V and 6.7x10(-8) A/cm(2), respectively, at a gate voltage of 5 V.