EAGER: Strain Engineering the Mechanical Properties of Black Phosphorus

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

With this EArly-concept Grant for Exploratory Research (EAGER), the team will investigate the feasibility of producing thin layers of phosphorus that, based on measurements and theoretical predictions, have more attractive electronic properties than thin layers of carbon. Ultrathin materials that consist of one or a few atomically-thin layers are being studied as alternatives for current silicon-based microelectronics. The electronic properties of thin layers of phosphorous change when subjected to deformation, enabling control by the application of external forces that would offer interesting device functionality when placed on flexible material supports. This project will demonstrate the effect of macro- and nano-scale bending on the electronic properties of thin phosphorus films. Being able to produce and control the properties of phosphorous would enable new materials and concepts for electronics. Insight from the combined experimental-theoretical approach to investigate strain in atomically thin layers would be applicable to other two-dimensional materials. The research program is integrated with an outreach program involving student recruitment in partnership with the Society of Hispanic Professional Engineers, Inc. and public education in relation to the Solar Vehicle Project. The goal of this research is to demonstrate strain engineering in atomically-thin membranes by combining experimental realization and characterization with computational investigation. Two-dimensional (2D) films of the phosphorus allotrope known as black phosphorus will be exfoliated onto silicon carbide and flexible substrates. It is expected that the black phosphorus will conform to patterns in the silicon carbide in a manner that depends on the number of phosphorus layers and pattern dimensions. The black phosphorus will be strained by application of a force to the flexible substrate. The strain introduced in the black phosphorus will be measured by Raman spectroscopy and scanning tunneling microscopy. The delamination from the patterns will be measured by atomic force microscopy. The experiments will be modeled by density functional-based theory to obtain a picture of the mechanical and electronic properties at the nanoscale in two-dimensional films. The understanding and control of strain will enable a new anisotropic, 2D electronic material that has a bandgap, and will establish a robust platform for achieving strain engineering in technologically important 2D films beyond graphene.