Thin film cavity ringdown spectroscopy and second harmonic generation on thin a-Si:H films

I. M.P. Aarts, B. Hoex, J. J.H. Gielis, C. M. Leewis, A. H.M. Smets, R. Engeln, M. Nesládek, W. M.M. Kessels, M. C.M. Van de Sanden

Onderzoeksoutput: Hoofdstuk in Boek/Rapport/CongresprocedureConferentiebijdrageAcademicpeer review

1 Citaat (Scopus)

Samenvatting

A set of 8 rf deposited a-Si:H thin films of various thickness (4-1031nm) have been used to explore the applicability of two optical techniques, thin film cavity ringdown spectroscopy (tf-CRDS) and second harmonic generation (SHG), for the measurement of small defect-related absorptions. In this paper we will give a first overview of the different aspects of these techniques, which are novel in the field of amorphous silicon materials. It is shown that tf-CRDS is capable of measuring defect-related absorptions (associated with dangling bonds) as small as 10-7 for a single measurement, without the need for elaborate calibration procedures. The results are compared with photothermal deflection spectroscopy (PDS) for a broad spectral range (0.7 -1.7 eV) and show good agreement. Furthermore the existence of a defect-rich surface layer with a defect density of 1.1 × 1012 cm-2 has been proven. The absorption spectrum of a 4 nm thin film has revealed a different spectral signature than a bulk dominated (1031 nm) film. The SHG experiments on a-Si:H films have shown that the second harmonic signal arises from the surface states and polarization dependent studies have revealed that the surface states probed have an ∞m-symmetry. From this it can be deduced that the absorbing surface states are isotropically distributed. A spectral scan suggests that the second harmonic signal, whose origin has not been unrevealed yet, has a resonance at an incident photon energy of 1.22 eV.

Originele taal-2Engels
TitelAmorphous and nanocrystalline silicon-based films - 2003 : symposium held April 22 - 25, 2003, San Francisco, California, U.S.A.
RedacteurenJ.R. Abelson
Plaats van productieWarrendale
UitgeverijMaterials Research Society
Pagina's111-116
Aantal pagina's6
ISBN van geprinte versie1-558-99699-0
StatusGepubliceerd - 1 dec 2003
Evenement2003 Amorphous and Nanocrystalline Silicon-Based Films Symposium - San Francisco, Verenigde Staten van Amerika
Duur: 22 apr 200325 apr 2003

Publicatie series

NaamMaterials Research Society Symposium Proceedings
Volume762
ISSN van geprinte versie0272-9172

Congres

Congres2003 Amorphous and Nanocrystalline Silicon-Based Films Symposium
Land/RegioVerenigde Staten van Amerika
StadSan Francisco
Periode22/04/0325/04/03
AnderSymposium A: "Amorphous and Nanocrystalline Silicon-Based Films" ; (San Francisco, Calif.) : 2003.04.22-25

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