Controlling the stacking and conversion in bilayer crystals and heterostructures by non-equilibrium synthesis and processing is very important to construct 2D moiré quantum materials. Here we will show how to introduce isotopes, laser thinning, and Raman spectroscopy to understand the bilayer growth mechanism in two-step chemical vapor deposition. Then we will describe a feedback approach to reveal and control the transformation pathways in bilayer 2D materials by pulsed laser deposition (PLD). We will focus on the transformation kinetics of bilayer WS2 crystals into Janus WSSe/WS2 and WSe2/WS2 heterostructures by hyperthermal implantation of laser-vaporized Se clusters. In situ ICCD imaging, ion probe, and spectroscopy diagnostics characterize the PLD plasma and are used to precisely control the kinetic energies of the Se species arriving at the substrate. In situ Raman spectroscopy is used to characterize the conversion kinetics and capture the metastable phases during transformation. DFT calculations, XPS, and atomic-resolution HAADF STEM are used to identify the compositions, vibrational modes, and structures for revealing the conversion mechanism of the bilayer crystals.
Automated platforms for synthesis are a necessity to increase the rate of discovery, synthesis, and optimization of materials to match the accelerating pace of theoretical predictions. Here, we introduce a novel pulsed laser deposition (PLD) platform that combines in situ Raman, photoluminescence, and white light reflectance spectroscopies as a material probe with intensified CCD (ICCD) imaging/spectroscopy and ion probe gas-phase PLD plume diagnostics. These diagnostics together with full automation and high-throughput synthesis schemes enable rapid synthesis and characterization with a Python-based dataflow for seamless integration with machine learning algorithms. Examples of in situ spectroscopy of 2D materials during growth and modification will be discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.