Abstract
Optical second harmonic (SH) spectroscopy with femtosecond pulses is a promising tool for real-time measurement of epitaxial growth rate and surface chemical processes during chemical vapor deposition at Si( 001) surfaces.1 As a basis for such applications, understanding of the physical mechanism by which surface hydrogen (H) alters the near-surface SH susceptibility is essential. Earlier work proposed relaxation of dimer-induced strain upon dihydride-ternrination as a mechanism.2 While probably important for high H-coverages (θH > 1 ML), this mechanism cannot explain strong SH spectroscopic changes observed for lower coverages (0 < θH < 1 ML),3 the important regime in growth monitoring. Quenching of space charge fields on monohydride passivation of surface dangling bonds provides an alternative mechanism, suggested by the important role of dcelectric-field-induced SH (EFISH) demonstrated in SH studies of Si(001) MOS structure.4 Here we report a complete SH azimuthal rotation spectroscopic study of variably-Hterminated undoped and heavily-p-typedoped Si(001) surfaces to obtain a comprehensive picture of the nonlinear spectroscopy of monohydride termination. The results support a model in which H-modulation of bulk space-charge EFISH plays important role for high-doping, while H-quenching of a strong near-surface electric field caused by local valence electron redistribution resulting from surface charge transfer dominates for low-doping.
© 1997 Optical Society of America
PDF ArticleMore Like This
J. I. Dadap, X. F. Hu, M. H. Anderson, M. ter Beek, O. A. Aktsipetrov, N. M. Russell, J. G. Ekerdt, and M. C. Downer
FD.4 International Conference on Ultrafast Phenomena (UP) 1996
X. F. Hu, Z. Xu, P. S. Parkinson, D. Lim, J. G. Ekerdt, and M. C. Downer
CFG4 Conference on Lasers and Electro-Optics (CLEO:S&I) 1997
J. I. Dadap, X. F. Hu, N. M. Russell, J. G. Ekerdt, M. C. Downer, and O. A. Aktsipetroy
QFF6 Quantum Electronics and Laser Science Conference (CLEO:FS) 1996