Super high-dielectric-constant oxide films for next-generation nanoelectronics and supercapacitors for energy storage

Dielectrics are electrical insulator materials, polarizable by opposite displacement of positive and negative ionized atoms via electric fields across the material’s thickness. Dielectrics are used in energy-storage capacitors, as key components in modern micro-/nanoelectronics, high-frequency and mobile communication devices, and life-saving microchips and other devices such as defibrillators and pacemakers implantable in humans. A key dielectric parameter is the dielectric constant (k), which largely controls the capacitance in capacitors with nanoscale area and dielectric layer thickness. Extremely high dielectric constants (k ≥1000) were observed in oxides (e.g., La1.8Sr0.12NiO4) with relaxor/ferroelectric materials and in combined semiconducting bulk properties with highly resistive grain boundaries. Giant dielectric constant films have also been demonstrated, based on integrating relatively low-dielectric-constant oxides into nanolaminate structures (e.g., TiOx/Al2O3; TiO2/HfO2) with tailored sublayer thicknesses, interfaces, and oxygen atom distributions. This overview article addresses the science and technology of high-dielectric-constant oxide materials with different compositions and structures.