Memory improvement in lead-free BiFeO3 ferroelectric with high-k Al2O3 buffer layer for non-volatile memory applications

Abstract

We report the deposition of ferroelectric lead-free BiFeO3 perovskite film on Si (100) substrate by RF magnetron sputtering using Al2O3 as buffer layer. X-ray diffraction and multiple-angle ellipsometric analysis show the pure ferroelectric phase and maximum refractive index of the BiFeO3 film at the annealing temperature of 500 °C. For different annealing temperature of Al2O3 film, amorphous film structure and refractive index in the range 1.7–1.77 has been observed. Metal–ferroelectric–metal (MFeM), metal–ferroelectric–silicon (MFeS), metal–insulator–silicon (MIS) and metal–ferroelectric–insulator–silicon (MFIS) structure have been fabricated with BiFeO3 ferroelectric and Al2O3 insulator layer to investigate the electrical characteristics. Improvement in the memory window from 2.3 V in MFeS structure to 4.8 V in MFeIS structure has been observed with 10 nm buffer layer at the annealing temperature of 500 °C. The MFe(100 nm)I(10 nm)S structure annealed at 500 °C shows the breakdown voltage of 38 V and no degradation in the polarization charge upto the read-write cycles of 108.