Orientation-dependent large plasticity of single-crystalline gallium selenide

Abstract

Unlike metals and alloys with high ductility, inorganic semiconductors are mostly ceramics with brittle nature due to covalent/ionic bonding. Recent studies have shown that some layered/van der Waals semiconductors could exhibit substantial room-temperature ductility, despite the fact that the underlying mechanisms remain to be understood. Here, we report that the van der Waals semiconductor gallium(II) selenide (GaSe) can have crystal-orientation-dependent large plasticity at room temperature. Through in situ tensile and compressive experiments inside electron microscopes, we demonstrate that microfabricated GaSe can have substantial ductility loaded along and slanted with the intralayer direction while showing predominantly elastic deformation perpendicular to the intralayer direction until brittle fracture. We further reveal that, despite the interlayer gliding as the main mechanism, cross-layer slips induced by buckling associated with stacking faults also contribute to the plasticity. This study offers insights to understand the ductility and plasticity of van der Waals semiconductors and shows promising flexible/deformable electronics and energy-device applications. • Crystalline GaSe exhibits substantial ductility upon loading along certain orientations • Orientation-dependent deformation mechanisms revealed by in situ mechanical testing • Large plasticity induced by van der Waals interlayer gliding and cross-layer slips • Ductile GaSe promising for flexible/deformable electronics and energy devices Inorganic semiconductors are often brittle. Wang et al. report that the thermoelectric semiconductor GaSe can exhibit substantial ductility upon compressive and tensile loading along certain orientations. The large plasticity is mainly attributed to van der Waals interlayer gliding, accompanied by cross-layer slips, suggesting its potential for applications in flexible/deformable electronics and energy systems.