Discipline: Technology and Engineering
Subcategory: Electrical Engineering
James Outlaw - Saint Augustine's University
Co-Author(s): Steven Koester and Matt Robbins, University of Minnesota, Minneapolis, MN
Over one hundred and one years ago the first successful synthesis of crystalline Black Phosphorus was formed. Crystalline Black Phosphorus is formed by heating white phosphorus, using a mercury catalyst and a seed crystal of black phosphorus. In 2014, black phosphorus was isolated in a twodimensional form by exfoliation from a bulk crystal and since then there has been a large research interest in the electronic and optical properties of the material. Black phosphorus has a direct band gap which is tunable with thickness and a high hole mobility making it interesting for electronic and optical applications. The purpose of this study was to develop a method to control the thinning of black phosphorus which tunes the mobility and the layer number of black phosphorus as whole due to the instability of black phosphorus. In order to thin the black phosphorus a Raman spectroscopy was performed as a first step. By performing a Raman spectroscopy allows for a ‘fingerprint’ to be provided for the flake of black phosphorus that is being observed. Raman spectroscopy is performed by using a laser light that interacts with molecular vibrations that causes a shift in energy, which allows for visible vibrations that allow for the ‘fingerprint’ to be formed. Once the Raman spectroscopy has been performed, Aluminum Oxide is removed by using Ammonium Hydroxide. Then Atomic Layer Deposition tool is used to perform the thinning process. This tool helps with allowing for ultra-thin particles to be deposited in a more precise controlled way by producing an atomic specified thickness of the black phosphorus being accessed. Once the thinning process has been completed another layer of Aluminum Oxide is deposited requiring for the entire procedure process to be repeated for the several trials needed. The results show that Black Phosphorus flake thin about 1 nm every 200 cycles. In conclusion, the thinning process works for the accessed measure, however there are some things that can be modified and adjusted to develop a new and more efficient method. We were not able to isolate every factor at this point due to time restraints. Further research is still being developed.
Funder Acknowledgement(s): This work was supported primarily by the National Science Foundation MRSEC and REU programs under Award Numbers DMR-1263062 & DMR1420013.
Faculty Advisor: Mark Melton, email@example.com