Carrier Multiplication-Induced Structural Change during Ultrafast Carrier Relaxation and Non-Thermal Phase Transition in Semiconductors

TL;DR

This study demonstrates that carrier multiplication can induce ultrafast, non-thermal phase transitions in semiconductors like Ge2Sb2Te5, challenging traditional thermal models and unifying previous experimental observations.

Contribution

It reveals that carrier multiplication alone can trigger phase transitions in semiconductors without lattice heating, offering a new perspective on ultrafast phase change mechanisms.

Findings

Carrier multiplication induces ultrafast phase transition in Ge2Sb2Te5.

The lattice remains cold during the transition, indicating a non-thermal process.

Unifies experimental findings with the plasma annealing model.

Abstract

While being extensively studied as an important physical process to alter exciton population in nanostructures at fs time scale, carrier multiplication has not been considered seriously as a major mechanism for phase transition. Real-time time-dependent density functional theory study of Ge2Sb2Te5 reveals that carrier multiplication can induce ultrafast phase transition in solid state despite that the lattice remains cold. The results also unify the experimental findings in other semiconductors for which the explanation remains to be the 30-year old phenomenological plasma annealing model.