Critical Disconnect Between Structural and Electronic Recovery in Amorphous GaAs during Recrystallization

TL;DR

This study reveals a disconnect between structural and electronic recovery during amorphous to crystalline transition in irradiated GaAs, showing that electronic properties do not fully recover even when structural reordering occurs.

Contribution

It uncovers the contrasting evolution of structure and electronic properties during recrystallization, emphasizing the non-congruence in recovery processes in amorphous GaAs.

Findings

Structural evolution occurs in two stages: slow epitaxial growth at low temperatures and rapid growth with nanotwin formation at high temperatures.

Electronic properties deviate further from pristine material after recrystallization than in the amorphous phase.

Structural recovery does not necessarily lead to electronic property recovery in irradiated GaAs.

Abstract

Understanding the evolution of structure and functionality through amorphous to crystalline phase transitions is critical for predicting and designing devices for application in extreme conditions. Here, we consider both aspects of recrystallization of irradiated GaAs. We find that structural evolution occurs in two stages, a low temperature regime characterized by slow, epitaxial front propagation and a high-temperature regime above dominated by rapid growth and formation of dense nanotwin networks. We link aspects of this structural evolution to local ordering, or paracrystallinity, within the amorphous phase. Critically, the electronic recovery of the materials is not commensurate with this structural evolution. The electronic properties of the recrystallized material deviate further from the pristine material than do those of the amorphous phase, highlighting the incongruence between structural and electronic recovery and the contrasting impact of loss of long range order versus localized defects on the functionality of semiconducting materials.