Effective formation of interface controlled Y2O3 thin film on Si(100) in a metal-(ferroelectric)-insulator-semiconductor structure

Yttrium was deposited on the chemical oxide of Si and annealed under vacuum to control the interface for the formation Of Y2O3 as an insulating barrier to construct a metal-ferroelectric-insulator-semiconductor structure. Two different pre-annealing temperatures of 600 and 700 degrees C were chosen to investigate the effect of the interface state formed after the pre-annealing step on the successive formation of Y2O3 insulator and Nd2Ti2O7 (NTC) ferroelectric layer through annealing under an oxygen atmosphere at 800 degrees C. Pre-anneal treatments of Y-metal/chemical-SiO2/Si at 600 and 700 degrees C induced a formation of Y2O3 and Y-silicate, respectively. The difference in the pre-anneal temperature induced almost no change in the electrical properties of the Y2O3/interface/Si system, but degraded properties were observed in the NTO/Y2O3/interface/Si system pre-annealed at 600 degrees C when compared with the sample pre-annealed at 700 degrees C. C-V characteristics of the NTO/Y2O3/Si structured system showed a clockwise direction of hysteresis, and this gap could be used as a memory window for a ferroelectric-gate. A smaller hysteric gap and electrical breakdown values were observed in the NTO/Y2O3/Si system pre-annealed at 600 degrees C, and this was due to an unintentional distribution of the applied field from the presence of an interfacial layer containing Y-silicate and SiO2 phases. (C) 2008 Elsevier B.V. All rights reserved.