Dynamic Designer Strain Distributions in Two-Dimensional Materials

Strain engineering of two-dimensional (2D) semiconductors has recently revealed exciting nanophotonic effects such as localized bandgap tuning, exciton funneling, and the creation of site-specific single photon emitters. While there has been significant progress in the theoretical understanding of nanoscale strain engineering over recent years, experimental progress is hindered by the presence of unintended strain in solid-state devices, blurring the relationship between the local strain environment and direct material response. We introduced a new strain engineering platform to investigate complex strain distributions by transferring 2D materials flakes onto nanostructures patterned in close proximity, enabling the study of a variety of strain distributions, such as uniaxial, biaxial, and triaxial strain within a single flake. The bright emission from thick flakes makes gallium selenide a fantastic material for understanding the relationship between local strain and optical response. In this talk, we will report dynamic local strain engineering of suspended 2D material flakes by using a novel micromechanical spring with designed nanoscale probes for inducing symmetry-controlled localized strain. By performing strain engineering measurements on suspended 2D materials instead of using patterned substrates, unintended strain originating from the surrounding environment is avoided. The presented research establishes a new platform for streamlining the quantitative understanding of material properties as a function of complex local strain in two-dimensional materials for quantum photonics applications.