Optical Properties of Silicon
The optical properties of silicon measure at 300K [Green1995]. While a wide range of wavelengths is given here, silicon solar cells typical only operate from 400 to 1100 nm. There is a more up to date set of data in Green 2008 [green_self-consistent_2008]. It is available in tabulated form from pvlighthouse as text and in graphical format.
The data on this page is also available as an Excel spreadsheet.
Absorption coefficient of silicon in cm-1 as a function of the wavelength. Silicon is an indirect bandgap semiconductor so there is a long tail in absorption out to long wavelengths. The data is graphed on a log scale. The drop in absorption at the band gap (around 1100 nm) is sharper than might first appear. See also absorption coefficient.
The absorption depth is the inverse of the absorption coefficient. An absoption depth of, for example, 1 um means that the light intensity has fallen to 36% (1/e) of its original value. See also absorption coefficient.
Real and (negative) imaginary components of the refractive index for silicon at 300 K.
The reflectivity of a polished silicon wafer is determined from the complex refractive index.
The data for the above graph is given below. As noted above, it is also available in a much more convenient Excel spreadsheet.
W - wavelength
a - absorption coefficient
n - real component of refractive index
k - extinction coefficient
refractive index = n - ik
W(nm) a(/cm) n k 250 1.84E+06 1.694 3.666 260 1.97E+06 1.800 4.072 270 2.18E+06 2.129 4.690 280 2.36E+06 3.052 5.258 290 2.24E+06 4.426 5.160 300 1.73E+06 5.055 4.128 310 1.44E+06 5.074 3.559 320 1.28E+06 5.102 3.269 330 1.17E+06 5.179 3.085 340 1.09E+06 5.293 2.951 350 1.04E+06 5.483 2.904 360 1.02E+06 6.014 2.912 370 6.97E+05 6.863 2.051 380 2.93E+05 6.548 0.885 390 1.50E+05 5.976 0.465 400 9.52E+04 5.587 0.303 410 6.74E+04 5.305 0.220 420 5.00E+04 5.091 0.167 430 3.92E+04 4.925 0.134 440 3.11E+04 4.793 0.109 450 2.55E+04 4.676 0.091 460 2.10E+04 4.577 0.077 470 1.72E+04 4.491 0.064 480 1.48E+04 4.416 0.057 490 1.27E+04 4.348 0.050 500 1.11E+04 4.293 0.045 510 9.70E+03 4.239 0.039 520 8.80E+03 4.192 0.036 530 7.85E+03 4.150 0.033 540 7.05E+03 4.110 0.030 550 6.39E+03 4.077 0.028 560 5.78E+03 4.044 0.026 570 5.32E+03 4.015 0.024 580 4.88E+03 3.986 0.023 590 4.49E+03 3.962 0.021 600 4.14E+03 3.939 0.020 610 3.81E+03 3.916 0.018 620 3.52E+03 3.895 0.017 630 3.27E+03 3.879 0.016 640 3.04E+03 3.861 0.015 650 2.81E+03 3.844 0.015 660 2.58E+03 3.830 0.014 670 2.38E+03 3.815 0.013 680 2.21E+03 3.800 0.012 690 2.05E+03 3.787 0.011 700 1.90E+03 3.774 0.011 710 1.77E+03 3.762 0.011 720 1.66E+03 3.751 0.010 730 1.54E+03 3.741 0.009 740 1.42E+03 3.732 0.008 750 1.30E+03 3.723 0.008 760 1.19E+03 3.714 0.007 770 1.10E+03 3.705 0.007 780 1.01E+03 3.696 0.006 790 9.28E+02 3.688 0.006 800 8.50E+02 3.681 0.005 810 7.75E+02 3.674 0.005 820 7.07E+02 3.668 0.005 830 6.47E+02 3.662 0.004 840 5.91E+02 3.656 0.004 850 5.35E+02 3.650 0.004 860 4.80E+02 3.644 0.003 870 4.32E+02 3.638 0.003 880 3.83E+02 3.632 0.003 890 3.43E+02 3.626 0.002 900 3.06E+02 3.620 0.002 910 2.72E+02 3.614 0.002 920 2.40E+02 3.608 0.002 930 2.10E+02 3.602 0.002 940 1.83E+02 3.597 0.001 950 1.57E+02 3.592 0.001 960 1.34E+02 3.587 0.001 970 1.14E+02 3.582 0.001 980 9.59E+01 3.578 0.001 990 7.92E+01 3.574 0.001 1000 6.40E+01 3.570 0.001 1010 5.11E+01 3.566 - 1020 3.99E+01 3.563 - 1030 3.02E+01 3.560 - 1040 2.26E+01 3.557 - 1050 1.63E+01 3.554 - 1060 1.11E+01 3.551 - 1070 8.00E+00 3.548 - 1080 6.20E+00 3.546 - 1090 4.70E+00 3.544 - 1100 3.50E+00 3.541 - 1110 2.70E+00 3.539 - 1120 2.00E+00 3.537 - 1130 1.50E+00 3.534 - 1140 1.00E+00 3.532 - 1150 6.80E-01 3.530 - 1160 4.20E-01 3.528 - 1170 2.20E-01 3.526 - 1180 6.50E-02 3.524 - 1190 3.60E-02 3.522 - 1200 2.20E-02 3.520 - 1210 1.30E-02 3.528 - 1220 8.20E-03 3.516 - 1230 4.70E-03 3.515 - 1240 2.40E-03 3.513 - 1250 1.00E-03 3.511 - 1260 3.60E-04 3.510 - 1270 2.00E-04 3.508 - 1280 1.20E-04 3.507 - 1290 7.10E-05 3.506 - 1300 4.50E-05 3.504 - 1310 2.70E-05 3.503 - 1320 1.60E-05 3.501 - 1330 8.00E-06 3.500 - 1340 3.50E-06 3.498 - 1350 1.70E-06 3.497 - 1360 1.00E-06 3.496 - 1370 6.70E-07 3.495 - 1380 4.50E-07 3.493 - 1390 2.50E-07 3.492 - 1400 2.00E-07 3.491 - 1410 1.50E-07 3.490 - 1420 8.50E-08 3.489 - 1430 7.70E-08 3.488 - 1440 4.20E-08 3.487 - 1450 3.20E-08 3.486 -
References
Section titled “References”- M. Green and M. Keevers, “Optical properties of intrinsic silicon at 300 K,” Progress in Photovoltaics: Research and Applications, vol. 3, pp. 189 - 192, 1995. https://doi.org/10.1002/pip.4670030303
- M. Green, “Self-consistent optical parameters of intrinsic silicon at 300 K including temperature coefficients,” Solar Energy Materials and Solar Cells, vol. 92, pp. 1305–1310, 2008. https://doi.org/10.1016/j.solmat.2008.06.009