Direct observation of Levy flight of holes in bulk n-InP

TL;DR

This study provides direct experimental evidence of Levy flight behavior in hole transport within bulk n-InP, revealing a power-law decay in photoluminescence intensity over millimeter scales, consistent with Levy-flight models.

Contribution

It is the first direct observation of Levy flight dynamics in hole transport in bulk semiconductors, validated by comprehensive optical measurements and theoretical modeling.

Findings

Hole distribution follows a Levy-flight process over millimeters.

Power-law decay of photoluminescence intensity observed.

Free-carrier absorption truncates Levy flights in heavily doped samples.

Abstract

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 Levy-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.