rodriguez_de_marcos_2016

L. V. Rodríguez-de Marcos, J. I. Larruquert, J. A. Méndez and J. A. Aznárez, “Self-consistent optical constants of SiO2 and Ta2O5 films”, Opt. Mater. Express 6, 3622 (2016)

Source record · Catalogue · Review register

DOI: 10.1364/ome.6.003622

Source kind: measurement

Recorded technique: Films by reactive electron-beam evaporation in O2 (1e-2 Pa; base pressure 8e-7 Pa for SiO2 after a ~420 K bake) onto substrates heated to 573 K, cooled at ~1 K/min: SiO2 56 nm (0.43 nm/s; on c-cut MgF2 for transmittance, on Si for ellipsometry) and 125 nm (1.71 nm/s; on a Si wafer, for EUV reflectance); Ta2O5 53 nm (0.44 nm/s). Transmittance (FUV) and near-normal (5 deg) reflectance (FUV-EUV) with a grazing-incidence toroidal-grating monochromator and a windowless discharge lamp, 12.5-200 nm; a Lambda-9 spectrophotometer, 190-1500 nm; SOPRALAB GES5E ellipsometry, 190-950 nm, at 76 and 77 deg (SiO2) and 63 deg (Ta2O5), fitted with one (SiO2) or three (Ta2O5) Lorentz oscillators. The optical constants follow from an iterative double Kramers-Kronig analysis (reflectance-phase and k-n), extended with CXRO (Henke) and Chantler data at short wavelengths and the Lorentz oscillators at long. Density from the critical angle of grazing-incidence X-ray reflectometry (Cu K-alpha, 0.154 nm) (pp. 3624-3625, 3632).

Materials in structured entries: None recorded.

Dataset quantities: None recorded.

Contents: 0 datasets; 0 formulas.

Curation notes

Journal pages 3622-3637 are pdf pages 1-16. Identity checked against the first page. The optical constants are in figures only (Fig. 5 SiO2, Fig. 6 Ta2O5, n and k against wavelength on linear and log axes; Figs. 7-10 the measurements recomputed from them): ‘The optical constants are available upon request’ (p. 3636). No datasets. The paper states the substrate temperature as 523 K in the abstract (p. 3622) and 573 K in the text and conclusions (pp. 3623-3624, 3636): a discrepancy, kept as printed.

DATA SOURCES BY RANGE (text pp. 3627-3628 and Table 1, p. 3629, read from the table image; the library’s cells are garbled): lambda < 30 nm, reflectance and k of an opaque film from the CXRO (Henke) database, k extended to ~4e5 eV with Chantler et al.’s data in the last iteration, using the X-ray densities; 30-115.2 nm, measured reflectance (reflectance-phase KK), k from iteration 1 then 3; 115.2-190 nm, k from transmittance (Beer-Lambert neglecting reflectance, then exact calculations; for Ta2O5 averaged with the KK k), reflectance measured, then (SiO2) calculated from iteration 2; 190-950 nm, the Lorentz-oscillator fit to ellipsometry; lambda > 950 nm, the oscillators extrapolated. Four KK integrations in all (R-phi, k-n, R-phi, k-n), giving {n_final, k_final}.

TEXT VALUES (pp. 3632-3636), for the record; the vocabulary has no quantity for mass density or sum-rule numbers, so they are notes only: - Density from the X-ray critical angle: SiO2 2.28 g/cm3, ‘85.4% of its bulk density’; Ta2O5 7.72 g/cm3, 93.2 % of bulk. - f-sum rule (Eq. 4): high-energy limit of n_eff 30 (SiO2) and 186 (Ta2O5) electrons per molecule, 29.96 and 184.32 with the relativistic correction; the integral of the present k gives 29.65 (SiO2) and 187.19 (Ta2O5): deviations ~1.0 % and -1.6 %. - Inertial sum rule (Eqs. 5-6): zeta = 6.5e-4 (SiO2) and 1.4e-5 (Ta2O5), against Shiles et al.’s satisfactory limit 0.005. - Windowed sum rules (Eqs. 7-16; Figs. 11-12): zeta within Shiles’s limits over the spectrum scanned, except the E^2-weighted rule (Eq. 14) at high-energy windows; n_eff(inf) of the windowed f-sum rule deviates by up to ~1.1 % (SiO2) and 1.9 % (Ta2O5) from 29.96 and 184.32, diverging at high energies (attributed to the Chantler and power-law extrapolations). The Ta2O5 k in the transparent range is larger than expected (p. 3630); its ellipsometry and transmittance could not be fitted by one model (p. 3631).

MATERIALS. SiO2 and Ta2O5 films (Ta2O5 registered in this extraction); MgF2 and Si are substrates only.

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets

No datasets are recorded.

Formulas

No formulas are recorded.

Corrections

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.