# Amorphous to Amorphous Insulator-Metal transition in GeSe$_3$:Ag glasses

## TL;DR

This study investigates an insulator-metal transition in GeSe3:Ag glasses, revealing that the transition involves growth of Ag-rich phases and changes in network composition, with significant conductivity contrast.

## Contribution

It demonstrates a method to induce and analyze insulator-metal transition in chalcogenide glasses using gap sculpting and DFT calculations.

## Key findings

- Metallic and insulating phases have nearly identical DFT energies.
- Conductivity contrast of approximately 10^8 between phases.
- Growth of Ag-rich phase correlates with increased conductivity.

## Abstract

We study an insulator-metal transition in a ternary chalcogenide glass (GeSe$_3$)$_{1-x}$Ag$_x$ for $x$=0.15 and 0.25. The conducting phase of the glass is obtained by using "Gap Sculpting" (Prasai et al, Sci. Rep. 5:15522 (2015)) and it is observed that the metallic and insulating phases have nearly identical DFT energies but have a conductivity contrast of ~10$^8$. The transition from insulator to metal involves growth of an Ag-rich phase accompanied by a depletion of tetrahedrally bonded Ge(Se$_{1/2}$)$_4$ in the host network. The relative fraction of the amorphous Ag$_2$Se phase and GeSe$_2$ phase is shown to be a critical determinant of DC conductivity.