Review of Nanolayered Post-transition Metal Monochalcogenides: Synthesis, Properties, and Applications

Quasi-Van der Waals Epitaxial Growth of γ′-GaSe Nanometer-Thick Films on GaAs(111)B Substrates

“…In recent decades, layered chalcogenides have garnered significant attention as advanced members in the field of two-dimensional (2D) semiconductors due to their wide range of stoichiometries and stacking sequences, broadly tunable band gaps, − and versatile optical properties. − Within this large family, GaSe is of interest for its potential in optical and optoelectronics applications. GaSe differs from most other 2D semiconductors in that the band gap of GaSe changes from an indirect transition of 3.3 eV to a direct transition of 2.1 eV as the film thickness increases from one layer to bulk. − Moreover, in a single layer of GaSe, the energy gap of the direct transition is only 0.092 eV higher than that of the indirect transition, making GaSe readily convertible into a direct-bandgap material through external stimuli even at atomically thin thicknesses.…”