Ultrafast (but Many-Body) Relaxation in a Low-Density Electron Glass

TL;DR

This paper investigates the ultrafast relaxation dynamics of photoexcited impurity states in low-density silicon:P electronic glass, revealing power-law relaxation, multi-particle mechanisms, and quantum effects over sub-nanosecond timescales.

Contribution

It provides the first detailed study of ultrafast relaxation processes in low-density electron glasses, highlighting distinct behaviors from higher-density systems.

Findings

Power-law relaxation occurs over sub-ns timescales.

Relaxation behavior depends strongly on temperature and fluence.

Evidence for multi-particle and quantum relaxation mechanisms.

Abstract

We present a study of the relaxation dynamics of the photoexcited conductivity of the impurity states in the low-density electronic glass, phosphorous-doped silicon Si:P. Using optical pump-terahertz probe spectroscopy we find strongly temperature and fluence dependent glassy power-law relaxation occurring over sub-ns time scales. Such behavior is in contrast to the much longer time scales found in higher electron density glassy systems. We also find evidence for both multi-particle relaxation mechanisms and/or coupling to electronic collective modes and a low temperature quantum relaxational regime.