Strain engineering photonic properties in monolayer semiconductors through mechanically-reconfigurable wrinkling

摘要

Inhomogeneous and three-dimensional strain engineering in two dimensional materials opens up new avenues to straintronic devices for control strain sensitive photonic properties. Here we present a method to tune strain by wrinkling monolayer WSe_2 attached to a 15 nm thick ALD support layer and compressing the heterostructure on a soft substrate. The ALD film stiffens the 2D material, enabling optically resolvable micron scale wrinkling rather than nanometer scale crumpling and folding. Using photoluminescence spectroscopy, we show the wrinkling introduces periodic modulation of the bandgap by 47 meV, corresponding with strain modulation from +0.67% tensile strain at the wrinkle crest to -0.31% compressive strain at the trough. Moreover, we show that cycling the substrate strain mechanically reconfigures the magnitude and direction of wrinkling and resulting band tuning. These results pave the way towards stretchable multifuctional devices based on strained 2D materials.