Zener Tunneling Breakdown in Phase-Change Materials Revealed by Intense Terahertz Pulses

TL;DR

This study demonstrates how intense terahertz pulses induce Zener tunneling in phase-change materials, leading to localized conductivity changes and filamentary crystal growth, advancing understanding of ultrafast phase transitions.

Contribution

It reveals the nonlinear effects of intense THz pulses on phase-change materials and details the spatial-temporal dynamics of crystallization induced by electric field concentration.

Findings

Zener tunneling increases conductivity in Ge2Sb2Te5 under THz irradiation.

Localized electric fields cause Joule heating and nanometer-scale crystal growth.

Filamentary conductive domains form across the sample due to field-induced crystallization.

Abstract

We have systematically investigated the spatial and temporal dynamics of crystallization that occurs in the phase-change material Ge2Sb2Te5 upon irradiation with an intense THz pulse. THz pump and optical probe spectroscopy revealed that Zener tunneling induces a nonlinear increase in the conductivity of the crystalline phase. This result indicates that the large electric field associated with the THz pulses causes a nonlinear increase only at the edge of the crystallized area. The electric field concentrating in this area causes a temperature increase via Joule heating, which in turn leads to nanometer scale crystal growth parallel to the field and the formation of filamentary conductive domains across the sample.