Large photoinduced absorption is observed in free-standing porous-silicon films in the spectral range from 1.1 to 2.5 eV by using a femtosecond pump-and-probe technique. The measured nonlinear transmission spectra have a very fast component with initial decay on the subpicosecond time scale. The spectral structure and temporal behavior of induced absorption show the presence of molecularlike Si complexes with well-defined energy levels and spectrally uniform picosecond relaxation dynamics.
ASJC Scopus subject areas
- Condensed Matter Physics