Abstract
An intense femtosecond pulse of visible light incident on the surface of a crystalline semiconductor can deposit energy in the electronic system in a time that is short compared to the electron–phonon coupling time. If the density of deposited energy is high enough, a layer of material at the surface may be able to disorder before appreciable energy is transferred from the electrons to the ions of the lattice.1 Pump–probe experiments on silicon rising 90-fs pulses showed a rise in reflectivity and a decay in second-harmonic generation (SHC) consistent with the melting of the surface layer after the excitation pulse2–4 Because the intensity of the reflected second-harmonic signal depends on crystallographic orientation, its decay serves as a sensitive probe of structural changes. GaAs offers the advantage offers SI that SHG is dipole-allowed in the bulk, so that the surface contribution is negligible compared to the strong bulk signal.
© 1992 Optical Society of America
PDF ArticleMore Like This
P. N. Saeta, J.-K. Wang, Y. Siegal, N. Bloembergen, and E. Mazur
MC8 International Conference on Ultrafast Phenomena (UP) 1992
Juen-Kai Wang, Peter Saeta, Yakir Siegal, Eric Mazur, and Nicolaas Bloembergen
PDP24 International Conference on Ultrafast Phenomena (UP) 1990
S. V Govorkov, V. I. Emel'anov, N. I. Koroteev, I. L. Shumay, T. Schroder, and W. Rudolph
QMB2 Quantum Electronics and Laser Science Conference (CLEO:FS) 1991