Crystallographic orientation dependent ferroelectric characteristics of (Bi_3.3,La_0.8)Ti₃O₁₂ (BLT) capacitors

The 70 nm thick (Bi_3.3,La_0.8)Ti₃O ₁₂ (BLT) thin films were fabricated by deposition multiple spin coating layers and then crystallized by RTA and FA on Pt/TiO_x/ SiO₂/Si substrate. Films were synthesized by MOD (metal organic decomposition) derived precursor to easy mass production. The randomly oriented BLT thin films have resulted from newly developed noble bake process, while a highly c-axis preferred orientation occurs for conventional baked thin film. The texture coefficient of I(004), I(117), I(111) and I(200) of noble baked BLT capacitors has 0, 0.24, 1.35 and 1.92, respectively. The films were very dense with no apparent pore site. The switching polarization (P*-P^{^}) and coercive voltage (2 Vc) of randomly oriented BLT thin films were nearly saturated at 3 V to have 20.03 μC/cm² and 1.38 V, respectively. However, strongly c-axis oriented thin films have 10.1 μC/cm² and 1.42 V for drive 3 V. The random orientation BLT shows good insulating behavior (9.4E-7 A/cm² at 3 V). Both randomly oriented capacitor and highly c-axis preferred orientation thin films show no degradation of polarization due to fatigue after 1E11 cycles using 3 V (428.5 kV/cm) bipolar square pulse at 1 MHz.