51. Ex situ variable angle spectroscopic ellipsometry studies on chemical vapor deposited boron-doped diamond films: Layered structure and modeling aspects.
- Author
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Gupta, S., Dudipala, A., Williams, O. A., Haenen, K., and Bohannan, E.
- Subjects
CHEMICAL vapor deposition ,BORON ,DIAMONDS ,LAYER structure (Solids) ,ELLIPSOMETRY ,REGRESSION analysis ,THIN films ,RAMAN spectroscopy - Abstract
We report the optical property measurements on boron-doped diamond (BDD) films which were synthesized by microwave plasma-assisted chemical vapor deposition technique on Si (100) using methane in high hydrogen dilution and trimethylboron as precursors with varying boron concentration such that [B]/[C]
gas =100, 500, 1000, 2000, 4000, and 6467 ppm. These BDD films were investigated using a rotating analyzer variable angle spectroscopic ellipsometry (SE) from the near IR to UV range (830–193 nm). By applying the conventional Bruggeman effective medium approximation and linear regression analyses to the raw SE data that is, [ψ(λi ),Δ(λi )] and pseudodielectric function (<[variant_greek_epsilon]r (λi )>,<[variant_greek_epsilon]i (λi )>), we determined the most appropriate model fit. The SE modeling was performed through the normal and point-by-point fit methods combined with the coupled and uncoupled bulk and surface layer approaches providing the details about the thin films’ microstructure in terms of the (a) multilayer (component and surface) structure and component layer thickness of the films, (b)volume fraction of constituents [fsp , f3 Csp and void (f2 Cv ) in the component layer], (c) inhomogeneity of the structure along the growth axis and its variation with boron concentration, and (iv) surface roughness layer thickness (ds ) with dimensions less than the optical wavelength that is not otherwise available. A simplified three-layer structural model consisting of an interfacial layer, an intermediate (or bulk) layer, and a top surface roughness layer has been proposed, which simulates the ellipsometry data reasonably well with coupled point-by-point method. An estimator, i.e., mean squared error (χ2 ), is used to assess the accuracy of the model fit. The... [ABSTRACT FROM AUTHOR]- Published
- 2008
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