Enhanced ductility of III-V covalent semiconductors from electrons and holes

Abstract

Covalent semiconductors exhibit low ductility arising from the resistance of the strong chemical bonds to deformation slip. It is important to soften these strong covalent bonds to improve the ductility of covalent semiconductors for their extended engineering applications. Here, we demonstrate from quantum mechanics simulations that the free carriers, including electrons and holes, can significantly weaken the strong covalent bonds of III-V covalent semiconductors, resulting in the modified general stacking fault energy surface and enhanced ductility. Furthermore, we establish the relationship between the carrier density and the energy barriers of deformation slip, in which the increased carrier concentration leads to an increased tendency of dislocation nucleation and higher ductility. The physical origin of this phenomenon arises from the contributions of extra carriers to the formation of new weak bonds at stacking fault layers along the slip plane, decreasing the energy barrier of deformation slip. Our results indicate that free electrons and holes play an important role in the mechanical properties of covalent semiconductors at high carrier concentrations. This provides the theoretical foundation to tune the mechanical properties of covalent semiconductors using injected carriers.