Light irradiation induced brittle-to-ductile and ductile-to-brittle transition in inorganic semiconductors

Abstract

The intrinsic brittleness of inorganic semiconductors prevents them from extended engineering applications under extreme condition of high temperature and pressure, making it essential to improve their ductility. Here, we applied the constrained density functional theory to examine the relationship between plastic deformation and photonic excitation in sphalerite ZnS and related II-IV semiconductors. We find that ZnS transforms from a dislocation dominated deformation mode in the ground state to a twin dominated deformation mode with bandgap electronic excitations, leading to brittle failure under light illumination. This agrees very well with recent mechanical experiments on single crystal ZnS.More interesting, we predict that the ZnTe and CdTe display the opposite mechanical behavior compared to ZnS, exhibiting ductility close to metallic level with bandgap illumination, but typical brittle failure in the dark state. Our results provide a general approach to design more shapeable and tougher semiconductor devices by controlling exposure to electronic excitation.Inorganic semiconductors have attracted enormous attention because of their widespread application in electronic devices, light-emitting diodes, thermoelectrics, and photovoltaic cells [1,2]. One of the main limitations in inorganic semiconductors is their brittle mechanical behavior. Fracture or yielding often occurs in these materials upon very small-scale strain induced by external stress [3][4][5]. Therefore, understanding, designing, and controlling of the mechanical properties of inorganic semiconductors are essential for their modern engineering applications. A very recent experimental study showed that sphalerite ZnS, a representative II-VI semiconductor, displays a brittle character under conditions of light irradiation[6], but, it becomes extraordinarily plastic when the deformation is performed in complete darkness. In addition, the brittle

Orientation Dependent Mechanical Responses and Plastic Deformation Mechanisms of ZnSe Nano Films under Nanoindentation

“…In addition, the energy barrier along the direction is higher than that in the [1][2][3][4][5][6][7][8][9][10] direction, indicating that it is energetically more favorable to glide along [1][2][3][4][5][6][7][8][9][10] direction. This result is in good agreement with previous experimental results [48], indicating the reliability of our calculations.…”

“…In our calculations, we find that the generalized stacking fault energy curve of <11-2>{111} system is asymmetric, while that of the <1-10>{111} system is symmetric. The maximum stacking fault energy of the <11-2>{111} system is about 1.4 J/m 2 , which agrees well with the first principles calculation result (1.1 J/m 2 ) [48]. In addition, the energy barrier along the direction is higher than that in the [1][2][3][4][5][6][7][8][9][10] direction, indicating that it is energetically more favorable to glide along [1][2][3][4][5][6][7][8][9][10] direction.…”

“…In our calculations, we find that the generalized stacking fault energy curve of <11-2>{111} system is asymmetric, while that of the <1-10>{111} system is symmetric. The maximum stacking fault energy of the <11-2>{111} system is about 1.4 J/m 2 , which agrees well with the first principles calculation result (1.1 J/m 2 ) [48]. In addition, the energy barrier along In our calculations, the constructed ZnSe models are divided into two parts by the (111) crystalline plane, as illustrated as the dash line in Figure 2a.…”

Solution‐Processed Stretchable Ag2S Semiconductor Thin Films for Wearable Self‐Powered Nonvolatile Memory

“…[ 8–12 ] However, finding candidates of stretchable semiconductors that have an appropriate bandgap and related electrical performance as well as mechanical and environmental durability has been challenging. [ 13,14 ] For instance, conventional inorganic semiconductors held by ionic or covalent bonds are intrinsically brittle and show only the strain of about 0.1–0.2%, [ 15–17 ] thus easily experiencing mechanical cracks due to the accumulation of fatigue under repetitive deformation, while organic‐based semiconductors are vulnerable to humidity, oxygen, and chemical and thermal stresses, and their inferior electrical properties; [ 18–21 ] therefore, they cannot fulfil the criteria for future deformable semiconductor devices.…”

Room‐temperature plastic inorganic semiconductors for flexible and deformable electronics

“…The light-modulated deformation mechanism in ZnS and other II-IV semiconductors was further studied by constrained density functional theory (CDFT). 71 Under light illumination, the deformation of ZnS is mainly controlled by twinning compared to a dislocation-dominated deformation mode without illumination. The research also suggested that crystals with more covalent component may exhibit ductility under light illumination such as ZnTe and ZnSe.…”