Excitonic Instability and Electronic Property of Two-dimensional AlSb Limit

TL;DR

This study predicts that two-dimensional monolayer AlSb exhibits excitonic instability and high mobility, making it a promising candidate for excitonic insulator applications and advanced electronic devices.

Contribution

First-principles and Bethe-Salpeter calculations reveal excitonic instability and electronic properties of monolayer AlSb, emphasizing the importance of spin-orbit coupling in its ground state prediction.

Findings

Excitonic instability due to exciton binding energy exceeding the energy gap by ~0.1 eV.

Monolayer AlSb is a direct gap semiconductor with high electron and hole mobilities (~1700 cm²/V·s).

Spin-orbit coupling is essential for accurate ground state prediction.

Abstract

Motivated by the recent synthesis of two-dimensional monolayer AlSb, we theoretically investigate its ground state and electronic properties using the first-principles calculations coupled with Bethe-Salpeter equation. An excitonic instability is revealed as a result of larger exciton binding energy than the corresponding one-electron energy gap by $\sim$0.1 eV, which is an indicative of a many-body ground state accompanied by spontaneous exciton generation. Including the spin-orbit coupling is proven to be a must to correctly predict the ground state. At room temperature, the two-dimensional monolayer AlSb is a direct gap semiconductor with phonon-limited electron and hole mobilities both around 1700 cm$^2$/V$\cdot$s. These results show that monolayer AlSb may provide a promising platform for realization of the excitonic insulator and for applications in the next-generation electronic devices.