Full Control of In-Plane Stress Tensor in Nanomembranes

The physical properties of materials depend on the inter-atomic distances of the constituent atoms which can be tuned by introducing strain fields conveniently. In this regard, the tailoring of the stress field in materials provides an unexplored degree of freedom that opens up a new horizon towards the unprecedented realization of engineered materials and new devices [1]. There has been significant experimental and theoretical progress on the study of strain effects in materials for a wide range of applications like topological insulators [2], nanophotonics [3], spintronics [4] and 2D materials [5,6]. However, the possibility of exerting fully controlled stress fields on demand was still missing until now [7]. In this talk, we will present a novel micro-machined piezoelectric actuator capable of introducing in-plane stress fields on demand in a GaAs semiconductor nanomembrane, which can be an ideal platform for the integration of many nanomaterials for elastic strain engineering applications. We successfully demonstrate deliberate and reversible uniaxial and isotropic/anisotropic biaxial stress fields in the nanomembrane at predefined positions [7]. As a further application of our actuator, we demonstrate for the first time wavelength-tunable polarization-entangled photons produced by any arbitrarily selected self-assembled InAs quantum dots embedded in a GaAs nanomembrane [8].