Engineering DyCrO3 ceramics toward room-temperature high-κ dielectric applications

Abstract

The search for a high-κ dielectric material that combines a high dielectric constant (ϵ′) and low dielectric loss is very crucial because of its widespread use in gate dielectrics to avoid the leakage current that arises due to continued miniaturization of present SiO2-based metal-oxide semiconductor field-effect transistor devices. RCrO3 (R is a rare-earth ion) materials have been at the center of interest because of their intriguing ferroelectric and magnetic properties, as well as their room-temperature colossal dielectric constant (CDC) values. Although CDC (ϵ′∼104) in RCrO3 materials is quite common, it is unsuitable for device applications since it is associated with a larger dielectric loss value (tan δ∼7 at 11 kHz). Here we have focused on polycrystalline DyCrO3, prepared using multiple synthesis techniques, and thoroughly investigated the origin and tuning of the various dielectric relaxations that give rise to CDC and large dielectric loss values. A clear understanding of the origin of dielectric relaxations enables us to design a specially synthesized DyCrO3 (SPS-DCO) in which the extrinsic dielectric relaxations driven large dielectric loss values can be completely suppressed and which is found to be associated with optimized high-κ dielectric properties [ϵ′∼130, tan δ∼0.06, and temperature coefficient of dielectric constant (TCϵ) ∼ 2280 ppm/K at 11 kHz, 300 K]. The only remaining intrinsic Debye-type dielectric relaxation in SPS-DCO arises due to electric-field-assisted charge hopping among various valences of Cr (investigated using x-ray photoelectron spectroscopy) that presently limits the lowest attainable loss value.