2 2 M ay 2 01 2 Direct observation of Lévy flight of holes in bulk n - InP

We study the photoluminescence spectra excited at an edge side of n-InP slabs and observed from the broadside. In a moderately doped sample the intensity drops off as a power-law function of the distance from the excitation — up to several millimeters — with no change in the spectral shape.The hole distribution is described by a stationary Lévy-flight process over more than two orders of magnitude in both the distance and hole concentration. For heavily-doped samples, the power law is truncated by free-carrier absorption. Our experiments are near-perfectly described by the Biberman-Holstein transport equation with parameters found from independent optical experiments.