Photoluminescence Differentiation of Zigzag and Armchair Edges of a Layered GaSe _0.5 Te _0.5 Alloy Crystal

Abstract Layered GaSe _0.5 Te _0.5 alloy crystals with hexagonal crystal structures and visible band‐to‐band transitions offer promising applications in electronics, photonics, and optoelectronics. Knowledge of these alloy crystal edges and orientations is crucial for device design, manufacturing and applications. Hence, a facile strategy for recognizing their zigzag/armchair edge structures is highly desired. Here, the edge‐dependent photoluminescence from the GaSe _0.5 Te _0.5 alloy crystal is observed, in which the correlations between emission features and edge structures have been revealed. The photoluminescence intensities in the edge regions are enhanced compared to the body region. Moreover, quantitative differences of phonon bands at the two types of edges have been distinguished by spatially‐resolved Raman scattering signals. The changes in photoluminescence and Raman scattering signals have been attributed to the edge‐related structures, where the in‐plane Type‐I quantum well forms due to the unintentional oxidation effect and facilitates carrier confinement at the edge regions. This work will benefit the fast identification of the crystal orientations of layered GaSe _0.5 Te _0.5 alloy crystals and the development of photonic devices with controllable edge‐emitting features.