Effective formation of interface controlled Y2O3 thin film on Si(1 0 0) 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 °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 (NTO) ferroelectric layer through annealing under an oxygen atmosphere at 800 °C. Pre-anneal treatments of Y-metal/chemical-SiO2/Si at 600 and 700 °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 °C when compared with the sample pre-annealed at 700 °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 °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.