Structure and Phase Control in 2D Semiconductor Synthesis and Heterostructure Assembly

Abstract:
Two-dimensional (2D) materials are poised to enable new frontiers in fundamental science and semiconductor technologies due to their unique electronic and optical properties at nanoscale dimensions. Even greater possibilities emerge when individual 2D crystals are assembled into van der Waals heterostructures (vdWHS), which enable atomically precise interfaces between diverse materials, and free control of the interlayer twist angle to engineer the band structure and moiré superlattice. However, the synthesis of 2D monolayers, multilayers, and vdWHS remains challenging. In this presentation, I will discuss our recent advances in transition metal dichalcogenide (TMD) synthesis and vdWHS assembly. We've adapted metal-organic chemical vapor deposition to use both vapor-phase chalcogens and liquid-phase metal precursors, facilitating quicker growth, easier doping, and polymorph control. We've also developed robotic assembly of vdWHS in vacuum, enabling the systematic arrangement of 2D material layers into vdWHS with precise layer composition and interlayer twist. Lastly, we've improved the characterization of these materials through hyperspectral reflectance microscopy and torsional force microscopy, expediting quality assessment and structural analysis.

Bio:
Andrew Mannix is an assistant professor of Materials Science and Engineering at Stanford University. He completed his B.S. in Materials Science and Engineering at the University of Illinois at Urbana-Champaign, and his Ph.D. in Materials Science and Engineering at Northwestern University as an NSF GRFP Fellow, where he worked on the growth and atomic-scale characterization of new 2D materials, including borophene. During his postdoctoral fellowship at the University of Chicago, Andy developed new methods of atomically-thin nanomaterials growth, processing, and automated heterostructure assembly. His lab at Stanford focuses on the growth, assembly and atomic-scale characterization of 2D materials for new electronic, optoelectronic, and quantum applications.