Ferroelectricity in 6 Angstrom-Thick Two-dimensional Ga$_2$O$_3$

TL;DR

This paper demonstrates ferroelectricity in atomically thin 2D Ga$_2$O$_3$, showing stability, low-voltage switching, and integration with silicon, opening new avenues for ultra-thin, high-density electronic devices.

Contribution

It reports the discovery of ferroelectricity in 6 Å-thick 2D Ga$_2$O$_3$, including a novel strain-induced phase transition and CMOS-compatible low-voltage switching.

Findings

Ferroelectricity observed in 6 Å-thick 2D Ga$_2$O$_3$

Strain reduces polarization switching voltage to 0.8 V

Successful integration with silicon technology

Abstract

Atomic-scale ferroelectric thin films hold great promise for high-density, low-power applications but face stability and voltage scaling challenges at extreme thinness. Here, we demonstrate ferroelectricity in single-crystalline two-dimensional (2D) Ga$_2$O$_3$, an ultra-wide-bandgap semiconductor, at just 6 angstrom thickness, exhibiting exceptional retention and thermal stability. We show that epitaxial beta-Ga$_2$O$_3$ can be exfoliated down to a half-unit cell thickness via a self-limiting mechanism, enabling a biaxial strain-induced phase transition into a novel ferroelectric layered structure. Strain modulation enables the reduction of polarization switching voltage to 0.8 V, meeting CMOS voltage scaling requirements. Theoretical calculations reveal that switching is driven by covalent bond reconstruction, effectively countering depolarization and enhancing stability. Additionally, we integrate ferroelectric 2D Ga$_2$O$_3$ onto silicon using a low-temperature, back-end-of-line-compatible process. This work advances the exploration of sub-nanometer ferroelectrics, paving the way for high-density, low-power, non-volatile applications seamlessly integrated with advanced silicon technology.