IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Monday Sessions
       Session SC+SS-MoA

Paper SC+SS-MoA5
Simplified Bond-Charge Model for the Analysis of Second-Harmonic-Generation Data: Application to Si/Dielectric Interfaces

Monday, October 29, 2001, 3:20 pm, Room 122

Session: Semiconductor Surfaces
Presenter: J.F.T. Wang, North Carolina State University
Authors: J.F.T. Wang, North Carolina State University
G.D. Powell, North Carolina State University
R.S. Johnson, North Carolina State University
G. Lucovsky, North Carolina State University
D.E. Aspnes, North Carolina State University
Correspondent: Click to Email
We develop a simplified bond-charge model for the analysis of second-harmonic-generateion (SHG) data, and apply it to study interfaces between singular and vicinal (001) and (111) Si substrates and various oxides, nitrides and oxynitrides. We model SHG microscopically as the 2@omega@t component of dipole radiation generated by the nonsinusoidal motion of electrons in bonds with anharmonic restoring forces, where the bonding electrons are driven by the @omega@t incident field. The simplfying assumption, which makes the treatment of SHG simpler than that of linear optics, is that only the anharmoic polarizability along the bond axis need be considered owing to the expected symmetry of the bond. Using this approach we analyze the azimuthal intensity dependence of SHG in the 800 to 900 nm spectral range of Si interfaces of various orientations and surface terminations. We find for example that a knowledge of the azimuthal dependence of the p-p signal for vicinal (111)Si allows us to predict the p-s, s-p, and s-s signals, and to determine the real and imaginary parts of the nonlinear polarizability associated with the different bonds. For interfaces between vicinal (001) Si samples and thin (less than 10 nm) thermally grown oxides, the essential absence of a 4-fold contribution to the azimuthal intensity dependence shows that these interfaces are double-domain. This result allows us to assign both SHG and RD signals of these interfaces to steps. Differences among oxidized samples and samples nitrided in various ways are relatively small, but systematic.