Thin film cavity ringdown spectroscopy and second harmonic generation on thin a-Si:H films
| Autor: | Aarts, I. M.P., Hoex, B., Gielis, J. J.H., Leewis, C. M., Smets, A. H.M., Engeln, R., Nesládek, M., Kessels, W. M.M., Van de Sanden, M. C.M., Abelson, J.R. |
|---|---|
| Přispěvatelé: | Applied Physics and Science Education, Plasma & Materials Processing, Atomic scale processing, Plasma-based gas conversion |
| Jazyk: | angličtina |
| Rok vydání: | 2003 |
| Zdroj: | Amorphous and nanocrystalline silicon-based films-2003 : symposium held April 22-25, 2003, San Francisco, California, U.S.A., 111-116 STARTPAGE=111;ENDPAGE=116;TITLE=Amorphous and nanocrystalline silicon-based films-2003 : symposium held April 22-25, 2003, San Francisco, California, U.S.A. |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|