The effect of dopants on the dielectric constant of HfO2 and ZrO2 from first principles

Abstract

Based on first-principles calculations, we elucidate the influence of dopants on the dielectric properties of the high-k materials HfO2 and ZrO2. Our calculations demonstrate that by doping the tetragonal phase can become energetically more favorable than the monoclinic phase present at ambient conditions. The stabilization of the tetragonal phase increases the dielectric constant significantly. A series of dopants was investigated to understand the efficiency and the mechanism of the stabilization process. The calculations reveal that at a moderate doping level (∼12%) only some of the dopants stabilize the tetragonal phase and that Si is the most efficient stabilizer atom.

Thermally induced permittivity enhancement in La-doped ZrO2 grown by atomic layer deposition on Ge(100)

“…8, 22, and 27, La-ZrO 2 was directly deposited on Ge͑100͒ without IL. The observed enhancement is consistent with the prediction by Fischer et al 13 that, upon introduction of Ge substitutional atoms, t-ZrO 2 can become energetically more favorable than m-or c-phases. Ge atoms, with a small i rad ͑ϳ0.53 Å͒, are readily incorporated in the thin La-ZrO 2 layer therein promoting the stabilization of t-ZrO 2 .…”

“…La incorporation in ZrO 2 ͑ϳ5% mean value͒ should enhance the value through doping induced effect. 13,14 La can also favor the interfacial La-O-Ge bonds, thus reducing Ge suboxides and electronic traps. 15,16 In this respect, O 3 oxidation was demonstrated to opportunely passivate Ge interface.…”

Oxide or carbide nanoparticles synthesized by laser ablation of a bulk Hf target in liquids and their structural, optical, and dielectric properties

“…The tetragonal and fcc are high temperature phases of hafnia and are observed at temperature above ~1700 °C and ~2500 °C, respectively, also at low pressure [30]. In traditional method of synthesis of hafnia nanoparticles these phases can be stabilized at much lower temperatures but by the addition into hafnia of rare earth dopants such as Y, Yb, Gd and others [31,32] or Si [33]. The origin of the peaks at 36.646°, 48.203° and 55.687° which are observed in the patterns for the nanoparticles synthesized in DI water (labeled with the symbol #) is still unknown, but they might be related to the orthorhombic phase of hafnia with space group Pbca termed as OrthoI which was determined from neutron diffraction studies [34].…”

Stabilization of cubic structure in Mn-doped hafnia

“…%, where the phase stability in bulks dependent on temperature, ionic radii and doping level of dopants was taken onto account. [3] Recently, Hf 0.5 Ti 0.5 O 2 was also believed to be potential a high-κ material due to enhanced dielectric responses from soft infrared-active phonon modes, [4] however, the Ti ions might serve as deep electron traps inducing localized levels in the gap and contribute to charged defects at high Ti concentrations. [5] It is interesting that reduction in charged defects associated with oxygen vacancies neutralizing the defect sites was predicted in the case of Ba incorporation into HfO 2 by Umezawa.…”