The Optical Spectra of a-Si:H and a-SiC:H Thin Films Measured by the Absolute Photothermal Deflection Spectroscopy (PDS)

Article Preview

Abstract:

The new absolute PDS setup allows to measure simultaneously the absolute values of the optical transmittance T, reflectance R and absorptance A spectra in the spectral range 280 2000 nm with the typical spectral resolution 10 nm in ultraviolet and visible spectral range and 20 nm in the near infrared region. The PDS setup provides the dynamic detection range in the optical absorptance up to 4 orders of magnitude using non-toxic liquid perfluorohexane Fluorinert FC72. Here we demonstrate the usability of this setup on a series of intrinsic as well as doped a-Si:H and a-SiC:H thin films deposited on glass substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (CVD) from hydrogen, silane and methane under various conditions. The increase of the Tauc gap with increasing carbon concentration in intrinsic a-SiC:H was observed. The defect-induced localized states in the energy gap were observed in doped a-Si:H as well as undoped a-SiC:H below the Urbach absorption edge.

You might also be interested in these eBooks

Info:

Periodical:

Solid State Phenomena (Volume 213)

Pages:

19-28

Citation:

Online since:

March 2014

Export:

Price:

Permissions CCC:

Permissions PLS:

Сopyright:

© 2014 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

* - Corresponding Author

[1] H. G. Tompkins, W. A. McGahan, Spectroscopic Ellipsometry and Reflectometry: a user's guide, J. Wiley & Sons, New York, (1999).

Google Scholar

[2] M. Vanecek, J. Kocka, J. Stuchlik, A. Triska, Direct measurement of the gap states and band tail absorption by constant photocurrent method in amorphous silicon, Solid State Commun. 39 (1981) 1199-1201.

DOI: 10.1016/0038-1098(81)91113-3

Google Scholar

[3] M. Vanecek, A. Poruba, Fourier-transform photocurrent spectroscopy of microcrystalline silicon for solar cells, Appl. Phys. Lett. 80 (2002) 719-721.

DOI: 10.1063/1.1446207

Google Scholar

[4] W. B. Jackson, N. M. Amer, A. C. Boccara, D. Fournier, Photothermal deflection spectroscopy and detection, Appl. Opt. 20 (1981), 1333-1344.

DOI: 10.1364/ao.20.001333

Google Scholar

[5] H. G. Grimmeiss, L. A. Ledebo, Spectral distribution of photoionization cross sections by photoconductivity measurements, J. Appl. Phys. 46 (1975) 2155-2163.

DOI: 10.1063/1.321858

Google Scholar

[6] J. Tauc, R. Grigorovici, A. Vancu, Optical Properties and Electronic Structure of Amorphous Germanium, Phys. Status Solidi 15 (1966) 627-637.

DOI: 10.1002/pssb.19660150224

Google Scholar

[7] R. A. Street, Hydrogenated Amorphous Silicon, Cambridge University Press, Cambridge, (1991).

Google Scholar

[8] D. Ritter, K. Weiser, Suppression of interference fringes in absorption measurements on thin films, Optics Communications 57 (1986) 336-338.

DOI: 10.1016/0030-4018(86)90270-1

Google Scholar

[9] Z. Remes, M. Vanecek, A. H. Mahan and R. S. Crandall, Silicon network relaxation in amorphous hydrogenated silicon, Phys. Rev. B 56 (1997) R12710- R12713.

DOI: 10.1103/physrevb.56.r12710

Google Scholar

[10] H. C. Bolton, The theoretical values of the polarizabilities of carbon-carbon bonds, Trans. the Faraday Soc. 50 (1954) 1261-1264.

DOI: 10.1039/tf9545001261

Google Scholar