Coordination imperfection enhanced electron-phonon interaction

Bond order length strength (BOLS) correlation between the size enhanced Stokes shift and the size-enlarged band gap expansion of porous silicon was derived. BOLS correlation allowed to discriminate the effect of electron-phonon coupling from the effect of crystal binding on the blueshift in photoemission and photoabsorption of nanosolid silicon. Matching the measured size dependence of the photoemission, photoabsorption and the band gap expansion provided an idea about the coordination number imperfection induced unusual behavior of photons, phonons and electrons in porous silicon. It was suggested that the shape and size dependency of a nanosolid is determined by the atomic coordination imperfection.