franta_2016#
D. Franta, D. Nečas, I. Ohlídal and A. Giglia, “Optical characterization of SiO2 thin films using universal dispersion model over wide spectral range”, Proc. SPIE 9890, 989014 (2016)
Source record · Catalogue · Review register
DOI: 10.1117/12.2227580
Source kind: measurement
Recorded technique: Combined spectrophotometry at near-normal incidence (reflectance from both sides, transmittance, their ratio) and variable-angle spectroscopic ellipsometry, 0.01-45 eV, all data fitted simultaneously in newAD2 with the Universal Dispersion Model (UDM) and a structural model (Rayleigh-Rice boundary roughness, thickness non-uniformity, a linear inhomogeneity found negligible). Table 2 (p. 2): Bruker Vertex 80v FIR spectrometry 0.01-0.084 eV (80-680 cm-1, 11 and 0 deg) and MIR 0.046-0.93 eV (370-7500 cm-1); Perkin Elmer Lambda 1050 NIR 0.69-1.44 eV (860-1800 nm, 6 and 0 deg) and UVV 1.46-6.6 eV (187-850 nm, 6 deg); McPherson VUVAS 2000 VUV 3.3-10.8 eV (115-380 nm, 10 deg); Elettra BEAR EUV 3-45 eV (24.8-413 nm, 4 deg); Woollam IR-VASE 0.037-0.8 eV (300-6500 cm-1, 55-75 deg); Jobin Yvon UVISEL 0.6-6.5 eV (190-2066 nm, 55-75 deg); Jobin Yvon UVISEL2 VUV 0.6-8.7 eV (143-2066 nm, 70 deg). The Lithosil Q2 plate’s model was fitted to ellipsometry and photometry together with Schott’s product-sheet index data (Fig. 20 caption) and, in the extreme ultraviolet, to the shape of Palik’s (Philipp’s) tables.
Materials in structured entries: SiO2
Dataset quantities: band_gap, extinction_coefficient, refractive_index
Contents: 11 datasets; 3 formulas.
Curation notes#
Pdf pages 1-15. Identity checked against the first page. The paper prints the optical constants only in figures (Figs. 20-23: n in the transparent range; n and k in the electronic and phonon ranges; k of the OH vibrations and localised states); the datasets are the authors’ published model tables from the newAD2 site, attached to the paper in the library with their URLs: 4001 rows of photon energy (eV), n and k, 0.01-100 eV on a logarithmic grid, kept as the files print them. The temperature is not stated (room temperature).
SAMPLES (Table 1, p. 2; image checked). Films on silicon single-crystal wafers, vacuum evaporated (Leybold Optics SYRUSpro DUV; prepared by Meopta), nominal thickness 800 nm from a quartz-crystal monitor (mass per area): X2546, 25 degrees C, 1 nm/s, optical thickness 878.4 nm, roughness sigma/tau 1.51/23.2 nm (AFM) and 1.51/20 nm (optical); X2551, 300 degrees C, 1 nm/s, 809.1 nm, 0.82/16.0 nm (AFM) and 0.30/20 nm (optical). The bulk sample is a Schott Lithosil Q2 fused-silica plate, 0.405 mm (the newAD2 file’s description).
FINDINGS (pp. 11-14). Density ratio X2546/X2551 = 809.1/878.4 = 0.921 from the thicknesses (Eq. 2, same mass per area), but 1279/1220 = 1.048 from the valence-electron transition strengths N_ve = N_vc + N_vx + N_ut + N_loc (Eqs. 3-4); fused silica has N_ve = 1116 eV^2 and n_ve = N_ve/N_a = 7.788 effective valence electrons (N_a = 143.3 eV^2 for pure silica, Eq. 5). The films hold water (X2546: peak at 1600 cm-1 and band at 2700-3700 cm-1, growing after exposure to air) and more OH than the plate; the plate is the densest O-Si-O network and the purest (sharpest Si-O modes at 1077, 802 and 458 cm-1, low absorption between 850 and 1000 cm-1); the films have a higher n in the transparent range and a smaller band gap. These sums reproduce from Table 3: 371 + 895 + 13 + 0.048 = 1279, 367 + 836 + 17 + 0.221 = 1220, 367 + 735 + 14 = 1116, 1116/143.3 = 7.788 (checked 2026-09-26).
TABLE 3 (p. 11; image checked). E_h (39.6 eV) and E_x (16.98 eV) are printed once, centred across the three columns: shared by the three models (the .par files agree); the library CSV puts them under X2551 only. Every Table 3 value is the rounded value of the .par files’ (e.g. E_g 7.673434680526896, 7.939173356933603, 8.36270918663193 eV; N_loc of X2546 0.0169 + 0.0315 = 0.048 from its two localised-state terms).
RANGES. The fitted ranges are those the newAD2 site states: Lithosil Q2 80 cm-1 to 8.5 eV, the films 80 cm-1 to 45 eV. Above 8.5 eV the Lithosil Q2 table follows the model fitted to the shape of Palik’s (Philipp’s) tables (‘the shape of absorption for fused silica corresponds to the Palik’s tabulated data because the experimental data were not available in the extreme UV region’, Fig. 21 caption): reproduced from philipp_1985, a separate dataset. Film rows above 45 eV are extrapolation and are not extracted. k is printed 0 where the model has no absorption (the transparent range).
COMPARISON. The refractiveindex.info page SiO2/Franta (‘numerical data kindly provided by Daniel Franta’) is the Lithosil Q2 table on another grid (0.0248-125 um, 3704 rows, to 50 eV): interpolated in log E, the Enk file agrees with it to a median 1.5e-6 in n and 2e-7 in k, at most 7e-4 (n) and 4e-4 (k) at sharp phonon features (interpolation); the films’ tables differ from it by up to 1.1 (checked 2026-09-26).
Recorded bibliographic identity status: VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
franta_2016/lithosil_q2_n#
{
"id": "lithosil_q2_n",
"material": "SiO2",
"file": "SiO2/franta_2016__lithosil_q2_n.csv",
"table": "data/LithosilQ2-SPIE9890.Enk",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"grade": "Lithosil Q2",
"form": "bulk",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
The Lithosil Q2 model’s n, 0.01-8.49 eV (the fitted range): the characterisation’s result on a 4001-point logarithmic grid (2930 rows here), not individual measurements; dense, so a fit should weight it as one curve. In the transparent range it is tied to Schott’s product-sheet index data (Fig. 20 caption).
franta_2016/lithosil_q2_k#
{
"id": "lithosil_q2_k",
"material": "SiO2",
"file": "SiO2/franta_2016__lithosil_q2_k.csv",
"table": "data/LithosilQ2-SPIE9890.Enk",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"grade": "Lithosil Q2",
"form": "bulk",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
As lithosil_q2_n, k (0 where the model has no absorption).
franta_2016/lithosil_q2_n_palik#
{
"id": "lithosil_q2_n_palik",
"material": "SiO2",
"file": "SiO2/franta_2016__lithosil_q2_n_palik.csv",
"table": "data/LithosilQ2-SPIE9890.Enk",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "reproduced",
"reproduced_from": [
"philipp_1985"
],
"parameters": {
"grade": "Lithosil Q2",
"form": "bulk"
}
}
The Lithosil Q2 table above 8.5 eV (8.51-100 eV, 1071 rows): the model fitted there to the shape of Palik’s (Philipp’s) tabulated data, not to measurements of this sample (Fig. 21 caption; newAD2 site).
franta_2016/lithosil_q2_k_palik#
{
"id": "lithosil_q2_k_palik",
"material": "SiO2",
"file": "SiO2/franta_2016__lithosil_q2_k_palik.csv",
"table": "data/LithosilQ2-SPIE9890.Enk",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "reproduced",
"reproduced_from": [
"philipp_1985"
],
"parameters": {
"grade": "Lithosil Q2",
"form": "bulk"
}
}
As lithosil_q2_n_palik, k.
franta_2016/film_X2546_n#
{
"id": "film_X2546_n",
"material": "SiO2",
"file": "SiO2/franta_2016__film_X2546_n.csv",
"table": "data/SiO2-X2546-SPIE9890.Enk",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "film",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
Film X2546 (vacuum evaporated at 25 degrees C onto Si, 878.4 nm, porous, with adsorbed water): the model’s n, 0.01-44.98 eV (the fitted range; 3654 rows).
franta_2016/film_X2546_k#
{
"id": "film_X2546_k",
"material": "SiO2",
"file": "SiO2/franta_2016__film_X2546_k.csv",
"table": "data/SiO2-X2546-SPIE9890.Enk",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "film",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
As film_X2546_n, k.
franta_2016/film_X2551_n#
{
"id": "film_X2551_n",
"material": "SiO2",
"file": "SiO2/franta_2016__film_X2551_n.csv",
"table": "data/SiO2-X2551-SPIE9890.Enk",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "film",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
Film X2551 (vacuum evaporated at 300 degrees C onto Si, 809.1 nm): the model’s n, 0.01-44.98 eV (the fitted range; 3654 rows). The SPIE 9890 version of the model.
franta_2016/film_X2551_k#
{
"id": "film_X2551_k",
"material": "SiO2",
"file": "SiO2/franta_2016__film_X2551_k.csv",
"table": "data/SiO2-X2551-SPIE9890.Enk",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "film",
"technique": "ellipsometry and spectrophotometry (UDM fit)"
}
}
As film_X2551_n, k.
franta_2016/band_gap_LithosilQ2#
{
"id": "band_gap_LithosilQ2",
"material": "SiO2",
"file": "SiO2/franta_2016__band_gap_LithosilQ2.csv",
"table": "tbl_a2a84171965e",
"quantity": "band_gap",
"unit": "eV",
"abscissa": "label",
"use": "primary",
"parameters": {
"kind": "optical",
"grade": "Lithosil Q2",
"form": "bulk"
}
}
Table 3, E_g ‘band gap energy’: the UDM’s interband-transition onset fitted for the Lithosil Q2 plate (below it the Urbach tail, E_u = 0.189 eV). A model parameter, not a threshold read from a spectrum.
franta_2016/band_gap_X2546#
{
"id": "band_gap_X2546",
"material": "SiO2",
"file": "SiO2/franta_2016__band_gap_X2546.csv",
"table": "tbl_a2a84171965e",
"quantity": "band_gap",
"unit": "eV",
"abscissa": "label",
"use": "primary",
"parameters": {
"kind": "optical",
"form": "film"
}
}
Table 3, E_g of film X2546 (UDM parameter; E_u = 0.50 eV).
franta_2016/band_gap_X2551#
{
"id": "band_gap_X2551",
"material": "SiO2",
"file": "SiO2/franta_2016__band_gap_X2551.csv",
"table": "tbl_a2a84171965e",
"quantity": "band_gap",
"unit": "eV",
"abscissa": "label",
"use": "primary",
"parameters": {
"kind": "optical",
"form": "film"
}
}
Table 3, E_g of film X2551 (UDM parameter; E_u = 0.42 eV).
Formulas#
franta_2016/udm_lithosil_q2#
{
"id": "udm_lithosil_q2",
"material": "SiO2",
"form": "udm",
"range_nm": [
24.8,
125000.0
],
"equation": "Universal Dispersion Model (the paper's Refs. 1 and 2: franta_2015, franta_2015b); basic parameters Table 3, p. 11",
"printed": "Table 3: N_vc = 367 eV^2, E_g = 8.36 eV, E_h = 39.6 eV, N_vx = 735 eV^2, E_x = 16.98 eV, N_ut = 14 eV^2, E_u = 0.189 eV, N_loc = - (column LithosilQ2)",
"variable": "E: photon energy in eV (phonon terms in cm-1 in the parameter file)",
"range": "80 cm-1 to 8.5 eV (fitted); above 8.5 eV fitted to the shape of Palik's (Philipp's) data",
"coefficients": {
"N_vc": "367",
"E_g": "8.36",
"E_h": "39.6",
"N_vx": "735",
"E_x": "16.98",
"N_ut": "14",
"E_u": "0.189"
},
"check": "Table 3's values are the parameter file's rounded (checked 2026-09-26); N_vc + N_vx + N_ut = 1116 eV^2, the N_ve the text gives (p. 13). The model itself is not implemented here: the parameter file's terms are he:ex=10:ut:ph=52 (interband with higher energies, ten excitonic terms, the Urbach tail, 52 phonon terms).",
"terms": {
"attributes": "he:ex=10:ut:ph=52",
"Nvc": "366.9467418127623",
"Eg": "8.36270918663193",
"Eh": "39.6024678126438",
"A0": "1",
"Aex1": "0.5316427008517485",
"Eex1": "10.27265667033163",
"Bex1": "0.2765733335525474",
"Aex2": "0.2027820567811606",
"Eex2": "10.40869429416461",
"Bex2": "0.1735051656437809",
"Aex3": "0.2018427690259914",
"Eex3": "11.23716443675481",
"Bex3": "0.2617876795701448",
"Aex4": "0.2156985363208976",
"Eex4": "11.57605606285452",
"Bex4": "0.3402309837436033",
"Aex5": "0.2243523614311426",
"Eex5": "11.89497250524933",
"Bex5": "0.4709428526322072",
"Aex6": "0.5661529191334149",
"Eex6": "12.3557224278071",
"Bex6": "0.9131304094234646",
"Aex7": "0.8746786472494885",
"Eex7": "13.7515974197821",
"Bex7": "1.114858060734488",
"Aex8": "1.172576738019447",
"Eex8": "16.51493612521",
"Bex8": "1.790835879274131",
"Aex9": "2.116260040703551",
"Eex9": "20.07201401044571",
"Bex9": "5.778786917148464",
"Aex10": "0.1563846840540854",
"Eex10": "39.6020282036981",
"Bex10": "9.209881987048114",
"Nvx": "735.4107760577147",
"Ex": "16.98219466591156",
"Nut": "13.66991985677169",
"Eu": "0.1890872899786315",
"Nph1": "0.0001579367908362486",
"nuph1": "351.0592097540114",
"betaph1": "155.1780556466652",
"Nph2": "0.0003783832077584816",
"nuph2": "353.7057813517702",
"betaph2": "417.7446796020989",
"Nph3": "0.001167972555285265",
"nuph3": "430.9254820575247",
"betaph3": "114.7455035453604",
"Nph4": "0.001503413069861931",
"nuph4": "446.4927613728527",
"betaph4": "42.98905162408492",
"Nph5": "0.001071876341182468",
"nuph5": "460.6962975553358",
"betaph5": "23.82030735392847",
"Nph6": "0.0002976032822475511",
"nuph6": "555.3091597389729",
"betaph6": "87.49807007519556",
"Nph7": "0.0004857618058699136",
"nuph7": "683.6604347118454",
"betaph7": "212.2882265427608",
"Nph8": "3.427719337399718e-05",
"nuph8": "744.0394747685669",
"betaph8": "33.97780415448126",
"Nph9": "0.0002102356375256169",
"nuph9": "791.1096221354356",
"betaph9": "35.04585453337063",
"Nph10": "0.000532646612112381",
"nuph10": "815.8033030169944",
"betaph10": "53.65047924380659",
"Nph11": "4.308122595590388e-05",
"nuph11": "881.1951744134609",
"betaph11": "80.85848597941744",
"Nph12": "0.01030365125507993",
"nuph12": "1067.768267615102",
"betaph12": "54.48518796494436",
"Nph13": "0.002234992995180967",
"nuph13": "1093.060934111671",
"betaph13": "32.25370143848671",
"Nph14": "0.002370004452914497",
"nuph14": "1109.257175589609",
"betaph14": "183.4843538412571",
"Nph15": "0.0004633533946198055",
"nuph15": "1152.097531082452",
"betaph15": "74.86915133277337",
"Nph16": "0.0003959576004524925",
"nuph16": "1209.392080059531",
"betaph16": "72.76564418568741",
"Nph17": "0.00018821796242105",
"nuph17": "1350.882837490379",
"betaph17": "325.5846033300886",
"Nph18": "1.126216549645647e-05",
"nuph18": "1516.451155347525",
"betaph18": "104.7372506190719",
"Nph19": "1.617788691082288e-05",
"nuph19": "1625.277864745127",
"betaph19": "84.17902107158315",
"Nph20": "2.61505058590848e-05",
"nuph20": "1649.268486099814",
"betaph20": "129.1719012563974",
"Nph21": "0.0001116558644383704",
"nuph21": "1828.746802277808",
"betaph21": "299.20133916978",
"Nph22": "2.9361800372863e-05",
"nuph22": "1873.513751569996",
"betaph22": "71.05319995047377",
"Nph23": "1.555885873876756e-05",
"nuph23": "1983.674372666704",
"betaph23": "89.30477756447488",
"Nph24": "9.363120409241714e-06",
"nuph24": "2023.486387006701",
"betaph24": "77.43102451855172",
"Nph25": "6.38552938062131e-07",
"nuph25": "2153.277377000553",
"betaph25": "87.61639513636975",
"Nph26": "3.449995884653931e-06",
"nuph26": "2261.673842322706",
"betaph26": "127.6740509508975",
"Nph27": "5.359776067172859e-07",
"nuph27": "2317.853357838011",
"betaph27": "122.9661734706691",
"Nph28": "4.941349061960409e-07",
"nuph28": "2388.276977221761",
"betaph28": "93.41476392533401",
"Nph29": "5.78728892049193e-07",
"nuph29": "2433.430959870009",
"betaph29": "114.6554567801446",
"Nph30": "1.130181021402629e-06",
"nuph30": "2550.960497589355",
"betaph30": "200.0094178310031",
"Nph31": "3.439163807903354e-07",
"nuph31": "2674.641662113736",
"betaph31": "108.5063930999388",
"Nph32": "2.840793314974757e-07",
"nuph32": "2782.006895286926",
"betaph32": "145.2059004681923",
"Nph33": "2.320418846178661e-08",
"nuph33": "2923.947038951354",
"betaph33": "99.84610665736612",
"Nph34": "4.317153650249912e-09",
"nuph34": "3185.932026796201",
"betaph34": "92.07992099281347",
"Nph35": "5.336333563925871e-07",
"nuph35": "3220.303913334323",
"betaph35": "829.8096098435042",
"Nph36": "1.268651759343399e-06",
"nuph36": "3600.349037249658",
"betaph36": "363.8027261751068",
"Nph37": "1.976535247848515e-06",
"nuph37": "3603.699885284117",
"betaph37": "178.3581858123089",
"Nph38": "4.529073137525764e-06",
"nuph38": "3624.95945707963",
"betaph38": "113.0128123078181",
"Nph39": "2.0662279268729e-06",
"nuph39": "3652.555597343321",
"betaph39": "66.87275905365507",
"Nph40": "1.859010312132641e-06",
"nuph40": "3676.82064691913",
"betaph40": "46.70725915212304",
"Nph41": "1.016515805706481e-06",
"nuph41": "3697.003432202047",
"betaph41": "30.80588411786115",
"Nph42": "3.414060185416213e-07",
"nuph42": "3855.908102875953",
"betaph42": "219.073740293254",
"Nph43": "6.208845187209287e-08",
"nuph43": "4071.744486784547",
"betaph43": "188.0684485424323",
"Nph44": "8.988945187319202e-16",
"nuph44": "4224.873249625495",
"betaph44": "80.51911498591025",
"Nph45": "1.660934501456605e-07",
"nuph45": "4448.578276108501",
"betaph45": "292.6379761867097",
"Nph46": "1.276838584193452e-07",
"nuph46": "4466.516394535184",
"betaph46": "121.8554614925231",
"Nph47": "5.992126372567601e-08",
"nuph47": "4526.49430918996",
"betaph47": "50.7487816290054",
"Nph48": "3.857322977406925e-09",
"nuph48": "4841.005293019718",
"betaph48": "189.2700050739375",
"Nph49": "2.26897507015326e-10",
"nuph49": "5256.953640216665",
"betaph49": "181.9620464789471",
"Nph50": "6.416204251769086e-08",
"nuph50": "7172.688438778629",
"betaph50": "257.0593740234171",
"Nph51": "3.866826202398356e-09",
"nuph51": "7195.90922321631",
"betaph51": "88.28789117238821",
"Nph52": "1.896121091059971e-08",
"nuph52": "7239.800540833135",
"betaph52": "62.91692653308822"
}
}
Schott Lithosil Q2 plate, 0.405 mm. ‘Complete set of dispersion parameters can be downloaded from newAD2 web pages’ (Table 3 caption): the file’s values are the terms below, and the file itself is attached to the paper in the curators’ library. The UDM’s equations are in franta_2015 and franta_2015b, not in this paper.
franta_2016/udm_X2546#
{
"id": "udm_X2546",
"material": "SiO2",
"equation": "Universal Dispersion Model (franta_2015, franta_2015b); basic parameters Table 3, p. 11",
"printed": "Table 3: N_vc = 371 eV^2, E_g = 7.7 eV, E_h = 39.6 eV, N_vx = 895 eV^2, E_x = 16.98 eV, N_ut = 13 eV^2, E_u = 0.50 eV, N_loc = 0.048 eV^2 (column X2546)",
"variable": "E: photon energy in eV (phonon terms in cm-1 in the parameter file)",
"range": "80 cm-1 to 45 eV (fitted)",
"coefficients": {
"N_vc": "371",
"E_g": "7.7",
"E_h": "39.6",
"N_vx": "895",
"E_x": "16.98",
"N_ut": "13",
"E_u": "0.50",
"N_loc": "0.048"
},
"check": "Table 3's values are the parameter file's rounded (checked 2026-09-26); N_ve = 1279 eV^2 as Eq. (3). Terms he:ut:ex=7:ph=43:loc=2."
}
Evaporated film, 25 degrees C, 878.4 nm.
franta_2016/udm_X2551#
{
"id": "udm_X2551",
"material": "SiO2",
"equation": "Universal Dispersion Model (franta_2015, franta_2015b); basic parameters Table 3, p. 11",
"printed": "Table 3: N_vc = 367 eV^2, E_g = 7.94 eV, E_h = 39.6 eV, N_vx = 836 eV^2, E_x = 16.98 eV, N_ut = 17 eV^2, E_u = 0.42 eV, N_loc = 0.221 eV^2 (column X2551)",
"variable": "E: photon energy in eV (phonon terms in cm-1 in the parameter file)",
"range": "80 cm-1 to 45 eV (fitted)",
"coefficients": {
"N_vc": "367",
"E_g": "7.94",
"E_h": "39.6",
"N_vx": "836",
"E_x": "16.98",
"N_ut": "17",
"E_u": "0.42",
"N_loc": "0.221"
},
"check": "Table 3's values are the parameter file's rounded (checked 2026-09-26); N_ve = 1220 eV^2 as Eq. (3). Terms he:ut:ex=7:ph=33:loc=2."
}
Evaporated film, 300 degrees C, 809.1 nm. The SPIE 9628 model of the same film (SiO2-X2551-SPIE9628) belongs to franta_2015b.
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.