Gd-substituted bismuth titanate film capacitors having ferroelectric reliability and large non-volatile charges

Fatigue-free Gd-modified bismuth titanate (Bi3.15Gd0.85Ti3O12; BGdT) film capacitors having stable charge-retaining characteristics were grown on Pt/TiO2/SiO2/Si(1 0 0) substrates using the method of metal-organic sol decomposition. The BGdT film capacitor with a top Pt electrode showed significantly improved values of the remanent polarization (2Pr) and the non-volatile charge as compared to those of the Bi4−xLaxTi3O12 (BLT; x=0.75) film capacitor, currently renowned as a promising candidate for non-volatile memories. The saturated 2Pr value of the BGdT capacitor was 75 μC/cm2 while it remained essentially constant up to 4.5×1010 read/write switching cycles at a frequency of 1 MHz. In addition to these, the capacitor demonstrated excellent charge-retention characteristics with its sensing margin of 52 μC/cm2 and a strong resistance against the imprinting failure.