Formation of Metal/Ferroelectric/Insulator/Semiconductor Structure with a CeO2 Buffer Layer

Abstract

Experimental results derived from the capacitance vs voltage (C-V) characteristics of metal/ferroelectric/insulator/semiconductor (MFIS) structures are described. PbTiO₃ ferroelectric films of 600 Å thickness were grown on CeO₂/Si(100) substrate by digital chemical vapor deposition (digital CVD). As the buffer layer between ferroelectric and Si substrate, 150-Å-thick CeO₂ intermediate epitaxial layers were grown on a (100) silicon substrate by vacuum evaporation. The density of surface states at the CeO₂/Si(100) interface was estimated from the C-V characteristics of Al/ CeO₂/Si(100) samples to be ∼10¹¹/cm² eV. Epitaxial CeO₂ films on Si(100) would therefore be expected to function as the gate oxide for MFS-FET's. Furthermore, the MFIS structure has ferroelectric switching properties, as demonstrated by the roughly 1-V threshold hysleresis in C-V characteristics. This structure is thus a first step toward high-performance MFIS-FET's.