Temperature controlled L\'evy flights of minority carriers in photoexcited bulk n-InP

TL;DR

This study demonstrates temperature-dependent Levy flight behavior of minority carriers in n-InP, revealing how temperature influences carrier spread and distribution through photon-assisted diffusion.

Contribution

It provides experimental evidence of temperature-controlled Levy flights of holes in n-InP, linking the Levy distribution index to the Urbach tailing parameter and temperature.

Findings

Gamma decreases with temperature, indicating more anomalous diffusion.

Carrier spread exceeds 1 cm at lower temperatures.

The observed behavior aligns with theoretical predictions based on the quasi-equilibrium emission spectrum.

Abstract

We study the spatial distribution of minority carriers arising from their anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP slab for temperatures ranging from 300 K to 78 K. The experiment provides a realization of the "L\'evy flight" random walk of holes, in which the L\'evy distribution index gamma is controlled by the temperature. We show that the variation \gamma(T) is close to that predicted earlier on the basis of the assumed quasi-equilibrium (van Roosbroek-Shockley) intrinsic emission spectrum, \gamma=1-\Delta /kT, where \Delta(T) is the Urbach tailing parameter of the absorption spectra. The decreasing \gamma at lower temperatures results in a giant enhancement in the spread of holes -- over distances exceeding 1 cm from the region of photo-excitation.