FreeElectronLaser

In order to study the possibility of in?quenching the phase containing predominantly Si–H bonds, while having minimal influence on the surrounding materials, samples of a-Si were exposed to Duke-FEL Mark III radiation. The wavelength of the radiation was selected to ?t the absorption maximum of stretching vibrations of Si–H bonds (5 mm). By varying the wavelength in the vicinity of 5 mm, the illumination time and the power density, di?erent types and degrees of structural ordering, of Si–H bonds and Si–Si bonds were obtained, and monitored by Raman spectroscopy. By increasing the energy density, at certain level the crystallization occurs. We were able to demonstrate a direct correlation between short and intermediate range ordering and the wavelength and intensity of the radiation. Using 5 mm at 10 kW/ cm2 leads to increase in structural disordering. However, increasing power to 60 kW/cm2 improves both short and intermediate order in a-Si :H, as demonstrated by Raman spectroscopy. Further increasing power density by an order of magnitude results in crystallization of the sample. ©2001 Published by Elsevier Science B.V.

Selective bond breaking in amorphous hydrogenated silicon by using Duke FEL

Thin amorphous hydrogenated silicon}carbon "lms, a-Si 1~xCx :H were deposited by magnetron sputtering on glass and mono-crystalline substrates with carbon content from x"0.2 to 1, wide variation of hydrogen concentration and di!erent degrees of structural ordering. The obtained "lms were investigated by Fourier transform infra-red (FTIR) spectroscopy, Raman spectroscopy, Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA). The results of the quantitative analyses obtained by the above-mentioned techniques were compared. It has been concluded that the applied vibrational methods can be used quantitatively which enables estimation of the degree of chemical ordering in the analysed samples. ©2001 Elsevier Science Ltd. All rights reserved.

Quantitative analysis of a-Si1~xCx :H thin "lms by vibrational spectroscopy and nuclear methods