Thickness dependence of the crystallization and phase transition in ZrO ₂ thin films

Abstract

Fluorite-structure binary oxides (e.g., HfO 2 and ZrO 2 ) have attracted increasing interest for a broad range of applications including thermal barrier coatings, high-k dielectrics, and novel ferroelectrics. A crystalline structure plays a crucial role in determining physical and chemical properties. Structure evolution of ZrO 2 thin films, particularly down to the nanometer scale, has not been thoroughly studied. In this work, we carried out systematic annealing analysis on the ZrO 2 thin films. Through in-situ high-temperature X-ray diffraction (XRD) characterizations, a thickness dependence of crystallization and phase transition is observed. Irrespective of the thickness (10-300 nm), the as-prepared amorphous ZrO 2 thin films are preferentially crystallized into a tetragonal (t) structure (high-temperature phase), which can be preserved down to room temperature (RT) upon annealing at the corresponding crystallization temperature (T C ). When annealing at temperatures higher than T C , the transition from t to monoclinic (m; RT phase) will occur, and the quantity of the transition strongly depends on the film thickness. Our work expands the basic understanding of the phase transition in the ZrO 2 thin films, and offers a path to the selective control over the phase structure for novel functionalities.

Effect of silver doping on electrical characteristics of aluminum/HfO2/p-silicon metal-oxide-semiconductor devices

“…It is thought that the film thickness increases due to these two crystal structures and weak molecular interconnections between the different phases. Similar changes have been reported in previous studies [32,33].…”

Nanocrystalline Cubic Phase Scandium-Stabilized Zirconia Thin Films

“…The ScSZ film's specific mass on the content is presented in Figure 11a, and their linearity, together with unexpected thic behavior, indicates the nonlinear dependence of the density of the as-deposited shown in Figure 11b on the impurity content. An increase in the Sc2O3 content to 6.25 mol% decreases the film's density from 3.6 g/cm 3 . Further increase in concentration leads to a rise in ScSZ density that rea maximum of 5.6 g/cm 3 at 12.5 mol%, which is close to the theoretical estimation o g/cm 3 for zirconia [64].…”

“…Recall that the lattice parameter and CSR of the ScSZ films d ited at RT also have singularities in the vicinity of this concentration. An increase in An increase in the Sc 2 O 3 content to 6.25 mol% decreases the film's density from 4.8 to 3.6 g/cm 3 . Further increase in concentration leads to a rise in ScSZ density that reaches a maximum of 5.6 g/cm 3 at 12.5 mol%, which is close to the theoretical estimation of 6.06 g/cm 3 for zirconia [64].…”

“…To this point, zirconia (ZrO 2 ) is a polymorphous material that exists in three crystallographic phases at atmospheric pressure: monoclinic stable up to 1205 °C, tetragonal from 1127 to 2396 °C, and cubic from 2369 to 2710 °C [ 2 ]. It was reported recently that the phase transition temperature depends on the film thickness [ 3 ]. The cubic zirconia demonstrates exceptional properties, such as high hardness [ 4 ] and dielectric constant [ 5 ], superior chemical stability [ 6 ], and prominent optical characteristics [ 7 ].…”

Fabrication and properties of pink 3 mol% yttria‐stabilized zirconia ceramics with high toughness

“…1,2 In particular, by virtue of its high mechanical properties, outstanding corrosion resistance, high-temperature resistance, good biocompatibility, and non-toxic to the human body, 3,4 ZrO 2 -based material has been widely used as decorative materials, grinding media, refractory materials, electronic components and biological materials. [5][6][7][8][9] Depending on the temperature, at atmospheric pressure, pure ZrO 2 exists in three crystallographic forms: monoclinic (m-ZrO 2 ) at ambient conditions and tetragonal (t-ZrO 2 ) and cubic (c-ZrO 2 ) at higher temperatures. 10 It is stable in the m-ZrO 2 phase from room temperature and up to 1170 • C. Between this temperature and 2370 • C, t-ZrO 2 is formed, while c-ZrO 2 is formed above 2370 • C up to the melting point of 2680 • C. 11,12 By adding a certain amount of stabilizing oxides such as yttrium oxide (Y 2 O 3 ), cerium oxide (CeO 2 ), or calcium oxide (CaO), the higher temperature phases can be stabilized at room temperature, [13][14][15] with Y 2 O 3 being the most commonly used.…”