GIIXRD spectra of DADA processed films: m-HfO2, Hf0.42Zr0.58O2, and t-ZrO2; vertical lines show table values for nearest monoclinic (m) and tetragonal (t) peaks.
Combined GIIXRD spectra (top) and diffracted intensity contour map as a function of the tilt angle (ψ) and d (bottom) of DADA processed (a) HfO2, (b) Hf0.42Zr0.58O2, and (c) ZrO2. Relevant monoclinic and tetragonal peaks and corresponding d-spacings are shown by vertical dashed lines. The high intensity regions in the contour maps which are circled are due to peaks from Si lattice planes. In the diffracted intensity contour maps, the tilt angle (ψ) ranges from ψ = 0 to ψ = 88°. GIIXRD data represent a part of real space map analog to pole figure at tilt angle of ψ ∼ 90°. The contour map (c) for the ZrO2 shows fiber texture for the t(111) peak (d ∼ 2.96A) at ψ < 10°. This peak is not observed in the contour map (a) of HfO2. Its onset is observed in the contour map (b) for Hf0.42Zr0.58O2. Similarly, the m(-111) (d ∼ 3.15 A) diffraction peak is observed in HfO2 and Hf0.42Zr0.58O2 but not in ZrO2 at ψ < 10°.
Normal incidence XAS at O K edge for (a) as deposited films and (b) DADA processed HfO2, Hf0.42Zr0.58O2, and ZrO2 films. For DADA m-HfO2 and t-ZrO2, arrows show peaks in sp band and extended region.
Qualitative molecular-orbital scheme: (a) metal d states, (b) qualitative molecular-orbital diagram to explain relationship between crystal structure and electronic structure in Hf1−xZrxO2, (c) crystal field splitting of metal d states in ligand fields for cubic, tetragonal, and monoclinic structures, and (d) structures in three different crystal symmetries for HfO2 and ZrO2 (cubic-Fm3m, tetragonal-P42/nmc, and monoclinic-P21/c).
X-ray absorption at the O K edge for Hf1−xZrxO2 (x = 0–1) processed using DADA scheme (normal incidence: 90° angle between the propagation vector of X-ray and the surface normal). Downward pointing arrows signify peaks beyond the unoccupied states in metal d region for films with Hf content x = 0, 0.58, and 1 for m-HfO2, mixed Hf0.42Zr0.58O2, and t-ZrO2, respectively.
(a) Polarization dependent X-ray absorption of the O K edge for HfO2 and ZrO2 films which were processed using the DADA scheme. Top panel: normal and grazing X-ray incidence for HfO2; bottom panel: normal and grazing X-ray incidence for ZrO2. (b), (c) Proposed scheme: X-ray beam direction, polarization vector of the beam; bottom: model structure with side view of monoclinic (-111) plane as expected from XRD pole figures.
(a) X-ray photoemission valence band spectra for 100 cycle Hf1−xZrxO2 (x = 0–1) films processed using DADA scheme. (b) XPS valence band spectra for unannealed HfO2, Hf0.42Z0.58O2, ZrO2 samples. Two arrows at each curve show the O 2p non-bonding states (at lower binding energy) and bonding states (at higher binding energy).
Imaginary part of the dielectric function of 100 cycle Hf1−xZrxO2 (x = 0–1) films from DADA process.
Electronic structure relative to the O 1s state for DADA samples: Energy of CBM, crystal field doublet (eg), and triplet (t2g), the minimum between d and sp states (“dip”), and s and p states and fine structure oscillatory peaks (osc1, osc2, and osc3).
Crystal field splitting parameters (Δ for as deposited and DADA processed films at O K edge). The theoretical crystal field splitting values from Ref. 34 are listed in the last column. The value for 58% Zr is estimated using the values for Zr oxide and Hf oxide.
Relative intensities of eg and t2g bands (and their ratios) for normal and grazing incidence for DADA processed HfO2 and ZrO2.
Electronic band edge structure relative to the vacuum level state for unannealed (AS DEP) and annealed (DADA) samples: Energy of VBM, valence band (VB) offset, and bandgap derived from combined XAS and XPS techniques. For comparison the bandgap values were extracted from SE data for comparison.
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