M. Hidalgo et al., LASER-INDUCED BREAKDOWN SPECTROMETRY OF TITANIUM-DIOXIDE ANTIREFLECTION COATINGS IN PHOTOVOLTAIC CELLS, Analytical chemistry, 68(7), 1996, pp. 1095-1100
Silicon photovoltaic cells have design and material requirements diffe
rent from those of most other silicon electronic devices. Not only are
nearly ideal silicon surfaces required, but also the bulk properties
must be of uniform high quality for high-energy conversion efficiency.
In this paper, emission spectra of laser-generated plasmas from titan
ium dioxide antireflection coatings in solar cells are reported, A pul
sed nitrogen laser at 337.1 nm was used with a pulse width of 10 ns an
d a laser fluence of 8.6 J/cm(2) onto the sample. The plasmas were det
ected using a charge-coupled device. Depth profilings from several sam
ples with different thicknesses of titanium dioxide have been studied.
A method for measuring thin TiO2 films based on the observation of su
ch profiles was developed. The effect of the laser fluence on the sens
itivity of the present method has been examined. Depth resolutions are
fluence-dependent but are on the order of 40 nm. The dependence betwe
en titanium dioxide plasma intensity and material reflectivity at the
laser wavelength is discussed. Another valuable aspect of the techniqu
e is the ability to perform measurements in a contactless manner at ro
om temperature and atmospheric pressure on wafer-sized samples.