Self-strain suppression of the metal-to-insulator transition in phase-change oxide devices

TL;DR

This study demonstrates that strain induced by lattice mismatch in phase-change oxide devices can suppress the metal-to-insulator transition, impacting device design and functionality at the nanoscale.

Contribution

It reveals how self-induced strain from ion irradiation suppresses phase transitions in V₂O₃, offering new insights for phase engineering in nanoscale devices.

Findings

Strain from lattice mismatch suppresses the metal-insulator transition.

Suppression occurs within irradiated regions or at edges depending on defect distribution.

Self-straining effects become significant as device dimensions shrink.

Abstract

Quantum materials exhibiting phase transitions which can be controlled through external stimuli, such as electric fields, are promising for future computing technologies beyond conventional semiconductor transistors. Devices that take advantage of structural phase transitions have inherent built-in memory, reminiscent of synapses and neurons, and are thus natural candidates for neuromorphic computing. Of particular interest are phase-change oxides, which allow for control over the metal-to-insulator transition. Here, we report X-ray nano-diffraction structural imaging of micro-devices fabricated with the archetypal phase-change material vanadium sesquioxide (V$_2$O$_3$). The devices contain a Ga ion-irradiated region where the metal-to-insulator transition critical temperature is lowered, a useful feature for controlling neuron-like spiking behavior. Results show that strain, induced by crystal lattice mismatch between the pristine and irradiated material, leads to a suppression of the metal-to-insulator-transition. Suppression occurs within the irradiated region or along its edges, depending on the defect-distribution and the size of the region. The observed self-straining effect could extend to other phase-change oxides and dominate as device dimensions are reduced and become too small to dissipate strain within the irradiated region. The findings are important for phase engineering in phase-change devices and highlight the necessity to study phase transitions at the nanoscale.