Photophysical ablation as a manifestation of mesoscopic effects in porous silicon*

Abstract

The dependence of the dynamics of photophysical ablation in porous silicon (PS) on the wavelength of laser radiation has been investigated experimentally. The ablation process was studied by recording the photoluminescence (PL) of excited electron-hole pairs both in bulk PS and in the ablation cloud of nanocrystallites. The dependence of the PL time constant on the excitation wavelength is evidence that the size of the crystallites in the ablation cloud is smaller, the shorter is the wavelength of the synchronized short-wavelength radiation. The experimental results are explained on the basis of the model of photophysical ablation proposed by B. S. Luk'yanchuk and a phenomenonological model of the breakdown of nanostructures. It follows from the model that the photoexcited carriers in the quantum filaments of porous silicon break them down as a consequence of spatially limited motion in one-dimensional quantum filaments. © 2004 Optical Society of America