Electric Field-Tunable Structural Phase Transitions in Monolayer Tellurium.

Electronic properties of monolayer tellurium (Te) with three proposed atomic configurations under external electric field were investigated through first-principles calculations. The calculated results demonstrate that α-Te and γ-Te have indirect band gaps, whereas β-Te, when no electric field is applied, can be considered as a direct semiconductor. An interesting structural change occurs in α- and γ-phase Te under a specific electric field strength, as does a change in structural chirality. In the presence of a perpendicular electric field, the band gaps can be modified and drawn close to 0 eV at a certain critical electric field strength. Before that, the band gaps of α-Te and γ-Te are nearly constant, while that of β-Te shows a quadratic relationship to electric field strength. These findings not only enrich our understanding of the electronic properties of monolayer tellurium but also show that monolayer tellurium has tremendous potential in nanoscale electronic devices owing to its tunable band gaps.