A Framework for WS_2 Nanoscroll Formation and Optical Analysis

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) exhibit favorably unique optical and electronic properties that make them promising building blocks for engineered heterostructures. Nanoscrolls, formed by rolling monolayer TMD flakes, are a simple and scalable way to create multi-layer structures. However, their formation process is not fully understood, and their resulting properties remain challenging to control. In this work, we develop an experimental framework for producing WS_2 nanoscrolls with improved yield and reproducibility. By systematically comparing flakes that roll with those that do not, we identify key factors, including flake size, shape, and experimental conditions, that govern the rolling process, and propose a practical rubric for selecting favorable flake candidates. We then use Raman and photoluminescence spectroscopy techniques to characterize the resulting structures and verify the presence of interlayer coupling. By comparing nanoscrolls formed under different fabrication conditions, we show how optical and electronic responses vary, and identify trends that link fabrication parameters to material behavior. Together, these results demonstrate that nanoscroll formation can be used not only to produce multi-layer structures, but also to begin controlling their properties. This thesis provides a foundation for using TMD nanoscrolls as a scalable and reliable method for engineering higher-order heterostructures.