Table I
Fluoride Films for Optical Applications
Starting material Deposition methoda (evap. temp.) Film composition Film structure packing density (p ), and substrate temp. (T s ) Transmittance range (μ m) α < 103 cm−1 Refractive index (n 1 ,n 2 ),b wavelength (μ m), and substrate temp. (T s ) Mechanical and chemical film properties NaF B (988°C)NaF Crystalline 0.2– 1.29–1.30 (0.55 μ m) Soft, soluble in water LiF B (870°C)LiF Crystalline 0.11–7 1.3 (0.55 μ m) Soft, hygroscopic CaF2 B (1280°C)CaF2 Crystalline 0.15–12 n 1 = 1.23(0.55 nm) Fairly hard, low tensile stress p = 0.57 → 1n 2 = 1.23–1.46(0.55 μ m) Na3 AlF6 B (1000°C)NaF Crystalline 0.2–14 1.32–1.35 (0.55 μ m) Soft, tends to recrystallization, low tensile stress Na3 AlF6 p = 0.88 (T s = 30°C)depending on film composition NaAlF4 p = 0.92 (T s = 190°C)AlF3 B ( )AlF3 Amorphous 0.2– n 1 = 1.23(0.55 μ m). Soft, low tensile stress p = 0.64 (T s = 35°C)n 2 –1.38(0.55 μ m) MgF2 B (1270°C)MgF2 Crystalline 0.11–4 1.32–1.39 (0.55 μ m) Hard at high T s , resistant against humidity, high tensile stress (cracking) p = 0.72 (T s = 30°C)in vacuum, depending on T s p = 0.98 (T s = 300°C)1.38–1.40 (0.55 μ m) in air, depending on T s ThF4 B (1100°C)ThF4 Amorphous (x ray) 0.2–15 n 1 = 1.50(0.55 μ m) Soft, medium tensile stress (T s = 35°C) n 2 = 1.52(0.55 μ m) Radioactive! (T s = 30°C) LaF3 B (1490°C)LaFa3 Crystalline 0.25–2 1.55 (0.55 μ m) Fairly hard p = 0.80(T s = 30° C)(T s = 300°C) Crystalline 1.65 (0.55 μ m) (T s = 300°C) NdF3 B (1410°C)NdF3 Crystalline 0.25– 1.61 (0.55 μ m) Fairly hard p = 0.80 (T s = 30°C)(T s = 300°C) CeF3 B (1360°C)CeF3 Crystalline 0.3–5 1.63 (0.55 μ m) Hard, high tensile stress p = 0.80 (T s = 30°C(T s = 300°C) PbF2 B (850°C)PbF2 β -PbF2 0.25–17 1.98 (0.3 μ m) Soft, <100 nm compressive >100 nm tensile stress! p = 0.91 (T s = 30° C)(T s = 30°C) 1.75 (0.55 μ m) (T s = 30°C)
a B = boat.
b n 1 = in vacuum,
n 2 = in air.
Table II
Nonoxide Chalcogenide and Semiconductor Films for Optical Applications
Starting material Deposition methoda (evap. temp.) Film composition Film structure, packing density (p ), and substrate temp. (T s ) Transmittance range (μ m) α < 10−3 cm−1 Refractive index (n ) wavelength (μ m), and substrate temp. (T s ) Chemical and mechanical film properties ZnS B (1100°C)ZnS Crystalline p ≥ 0.94/(T s = 35°C) 0.4–14 2.3 (0.55 μ m) (T s = 35°C) Soft, medium compressive stress CdS B (800°C)CdS Crystalline 0.55–7 2.5 (0.6 μ m) Soft ZnSe B (950° C)ZnSe Crystalline 0.55–15 2.57 (0.6 μ m) (T s = 30°C) Soft ZnTe B (1000°C)ZnTe Crystalline — 2.8 (0.55 μ m) Soft Sb2 S3 B (370°C)Sb2 S3 — 0.5–10 3.0 (0.55 μ m) Soft Ge30 As17 Te30 Se23 E Ge30 As17 Te30 Se23 Amorphous — 3.1 (10.6 μ m) Toxic InSb B b InSb — 7–16 4.3 (1.0 μ m) Toxic InAs B b InAs — 3.8–7 4.5 (1.0 μ m) Toxic PbTe B (850°C)PbTe — 3.5–20 5.6 (5.0 μ m) Soft, toxic Si B or E (1500°C)Si Amorphous up to T s = 300°C 1–9 3.4 (3.0 μ m) Hard Ge B or E (1600° C)Ge Amorphous up to T s = 300° C 2–23 4.4 (2.0 μ m) (T s = 30°C) Fairly hard
a B = boat,
E = electron beam.
b Controlled evaporation from two sources.
Table III
Oxide Films for Optical Applications
Starting material Deposition method.a (evap. temp.) Film composition Film structure packing density (p ), and substrate temp. (T s ) Transmittance range (μ m) α < 103 cm−1 Refractive index (n ) wavelength (μ m), and substrate temp. (T s ) Chemical and mechanical film properties SiO2 E (~1600°C)SiO2 Amorphous 0.2–9 1.45–1.46 (0.55 μ m) Hard and resistant by deposition on heated substrate, compressive stress p = 0.9 (T s = 30°C)p = 0.98 (T s = 150°C)SiO B ,R (~1300°C)Si2 O3 Amorphous 0.4–9 1.55 (0.55 μ m) Hard by deposition on heated substrate (T s = 30° C) Al2 O3 E (2050°C)Al2 O3 Amorphous 0.2–7 1.54 (0.55 μ m) Hard and resistant p = 1 (T s = 30°C)(T s = 40° C) p = 1 (T s = 300°C)1.63 (0.55 μ m) (T s = 300°C) MgO E (2800°C)MgO Crystalline 0.2–8 1.7 (0.55 μ m) Hard and resistant (T s = 50°C) 1.74 (0.55 μ m) (T s = 300° C) Nd2 O3 B ,R (1900°C)Nd2 O3 — 0.4– 1.79 (0.55 μ m) Hard 2.15 (0.55 μ m) (T s = 260°C) Gd2 O3 B ,R (2200°C)Gd2 O3 — 0.32–15 1.8 (0.55 μ m) Fairly hard ThO2 E (3050°C)ThO2 — 0.3– 1.95 (0.30 μ m) Radioactive! 1.86 (0.55 μ m) Hard (T s = 250°C) Y2 O3 E ,R (2400°C)Y2 O3 Amorphous, at higher T s partially crystalline 0.3–12 1.89 (0.33 μ m) Hard 1.87 (0.55 μ m) (T s = 250° C) 1.83 (0.9 μ m) Sc2 O3 E ,R (2400°C)Sc2 O3 Amorphous, at higher T s partially crystalline 0.35–13 1.90 (0.30 μ m) Fairly hard 1.89 (0.55 μ m) 1.86 (0.9 μ m) (T s = 250–300° C) La2 O3 B or E ,R (1500°C)La2 O3 Amorphous 0.3– 1.98 (0.33 μ m) Hard 1.9 (0.55 μ m) (T s = 300°C) Pr6 O11 B ,Pr6 O11 Amorphous 0.4– 1.92–2.05 (0.55 μ m) Fairly hard ZrO2 E ,R (2700°C)ZrO2 — 0.34–12 1.97 (0.55 μ m) Hard and resistant p = 0.67 (T s = 30°C)(T s = 30°C) p = 0.82 (T s = 250°C)2.05 (0.55 μ m) T s = 200° C)2.11 (0.40 μ m) (T s = 250°C) HfO2 E ,R HfO2 — 0.22–12 2.15 (0.25 μ m) Fairly hard (T s = 250°C) 1.95 (0.55 μ m) SiO B , (~1300°C)SiO Amorphous 0.7–9 2.0 (0.7 μ m) Hard, tensile stress (T s = 30°C) Ta2 O5 E ,R (2100°C)Ta2 O5 Amorphous 0.35–10 2.25 (0.40 μ m) Hard and resistant 2.1 (0.55 μ m) (T s = 250°C) ZnO B (1100°C)ZnO Crystalline 0.4– 2.1 (0.55 μ m) Soft (T s = 30°C) CeO2 B or E (1600°C)CeO2 Crystalline 0.4–12 2.2 (0.55 μ m) Fairly hard TiO B ,R (1750°C)TiO2 Amorphous (T s = 30°C) 0.4–3 1.9 (0.55 μ m) Hard and resistant, tensile stress Crystalline (T s > 100°C) (T s = 30°C) 2.3 (0.55 μ m) (T s = 220°C) 2.55 (0.55 μ m) (T s = 260°C) PbO B , (900°C)PbO Crystalline 0.53– 2.6 (0.55 μ m) Soft
a B = boat.
E = electron beam.
R = reactive deposition in O
2 .
Table IV
Absorption Coefficient k and Extinction Coefficient k ′ of Well-Prepared Sulfide and Fluoride Films
Film Ref. k (1060 nm)k (515 nm)k ′ (633 nm)ZnS 8 4.0 × 10−6 2.7 × 10−4 — ZnS 9 >3.5 × 10−5 ThF4 8 2.0 × 10−6 5.0 × 10−6 — MgF2 8 6.0 × 10−6 9.0 × 10−5 — CeF3 9 — — 1.4 × 10−6 NdF3 9 — — 1.2 10−5
Table V
Absorptivity A , Absorption Coefficient k , and Extinction Coefficients k ′ of Some Oxide Films Deposited Under Different Conditions
Film (starting material) Ref. O2 pressure (mbar) (ionization of O2 ) 1060 nm 515 nm 633 nm k ′
A %k A %k TiO2 (TiO) 8 4 × 10−4 (No) 0.290 2.5 × 10−4 1.510 7.5 × 10−4 — TiO2 (TiO) 8 4 × 10−4 (Yes) 0.090 7.7 × 10−5 1.250 5.5 × 10−4 — TiO2 (Ti) 8 6 × 10−4 (Yes) 0.098 7.9 × 10−5 2.520 1.1 × 10−3 — ZrO2 (ZrO2 ) 8 2 × 10−4 (No) 0.020 2.0 × 10−5 0.480 1.6 × 10−4 — ZrO2 (ZrO2 ) 8 2 × 10−4 (Yes) 0.025 2.1 × 10−5 0.490 1.8 × 10−4 — ZrO2 (ZrO2 ) 8 7 × 10−5 (No) — — — — 1.2 × 10−5 Al2 O3 (Al2 O3 ) 8 2 × 10−4 (No) 0.011 8.0 × 10−6 0.073 2.3 × 10−5 — Al2 O3 (Al2 O3 ) 9 7 × 10−5 (No) — — — — 2.3 × 10−5 10 — — — 3.5 × 10−5 SiO2 (SiO2 ) 8 6 × 10−5 (No) 0.005 2.0 × 10−6 0.060 1.5 × 10−5 — SiO2 (SiO2 ) 8 6 × 10−5 (Yes) 0.005 2.0 × 10−6 0.050 1.3 × 10−5 — CeO2 (CeO2 ) 9 7 × 10−5 (No) — — — — 2.3 × 10−5 MgO (MgO) 9 1 × 10−4 (No) — — — — 2.8 × 10−5
Table VI
Low-Loss Films as Waveguides in Integrated Optics
Film material Ref. Wavelength (nm) dB · cm−1 Losses k ′ α ′ cm−1 Preparation Ta2 O5 11 633 0.9 1 × 10−6 0.21 Ta sputtering oxidation in air CAS 10 (Planer, GB) 12 633 1.1 1.2 × 10−6 0.25 Electron beam evaporation in high vacuum Organosilicon 13 ,14 633 0.04 5 × 10−8 0.01 RF discharge in gaseous organosilicon compounds
Table VII
Refractive Indices of MgF2 Films Deposited Under Different Conditions
Ref. Residual gas pressure (mbar) Gas composition Substrate Temp (°C) Refractive inde× of the film, λ = 633 nm
In vacuum In air 42 2 × 10−9 Free of water 30 1.326 1.383 42 1 × 10−5 90% N2 30 1.328 1.385 42 1 × 10−5 90% H2 O 30 1.341 1.385 42 1 × 10−7 40% H2 O 280 1.384 1.385 38 3 × 10−5 Dry air 30 1.32a 1.39a 37 5 × 10−6 Dry air 30 1.33 —
a λ = 550 nm.
Table VIII
Temperature Coefficient of the Refractive Index dn /dT and the Linear Expansion Coefficientsβ of Different Materials in the 25–65°C Range69 ,70
Material: dn /dT · 10−5 · °C−1 wavelength (μ m)
β · 10−6 · °C−1 Polycrystalline (pc ) single crystal (sc ) 0.633 1.15 3.39 10.6 ZnSe (pc ) 9.11 5.97 5.34 5.20 7.8 ZnS (pc ) 6.35 4.98 4.59 4.63 6.9 CdTe (pc ) — 14.73 9.82 9.80 5.0 CaF2 (pc ) −1.31 −1.34 −1.28 — 19.5 BaF2 (pc ) −1.64 −1.68 −1.63 — 19.0 GaAs (sc ) — — — 5.64 —