Giant dielectric constant dominated by Maxwell-Wagner relaxation in Al ₂ O₃ / TiO₂ nanolaminates synthesized by atomic layer deposition

Nanolaminates consisting of Al₂ O₃ and TiO ₂ oxide sublayers were synthesized by using atomic layer deposition to produce individual layers with atomic scale thickness control. The sublayer thicknesses were kept constant for each multilayer structure, and were changed from 50 to 0.2 nm for a series of different samples. Giant dielectric constant (∼1000) was observed when the sublayer thickness is less than 0.5 nm, which is significantly larger than that of Al₂ O₃ and TiO ₂ dielectrics. Detailed investigation revealed that the observed giant dielectric constant is originated from the Maxwell-Wagner type dielectric relaxation.