1D Plasticity in Semiconductor Crystals.

Abstract

The exceptional plasticity recently found in inorganic semiconductors can be classified into two types: the three-dimensional (3D) orientation-insensitive deformability in polycrystals, and the two-dimensional (2D) anisotropic case in layered crystals. It is thus highly anticipated that one-dimensional (1D) plasticity should also exist but it has not been found yet. Here this work reports the excellent 1D plasticity in tin selenide (SnSe) semiconductor crystals. In in-plane directions, the bending strain is as large as ∼22.7% for the zig-zag-aligned specimen (plasticity) while as small as ∼1.4% for the armchair-aligned one (brittleness). Such 1D plasticity is ascribed to the coherent and stronger bond topology along b-axis that allows for multiple deformation mechanisms including layer segments, interlayer slip, bridging, lattice distortion, and dislocations. This bonding topology enables that the 1D plasticity is also observed in isostructural SnS and GeSe crystals. High-performance shape-conformable thermoelectric generators are then successfully developed using materials with 1D plasticity. This work enriches the diagram for plasticity and thus provides a new direction for the design and discovery of ductile semiconductors.