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Xiangfeng Duan1

1, University of California-Los Angeles, Los Angeles, California, United States

Semiconductor heterostructures are central for all modern electronic and optoelectronic devices. Traditional semiconductor heterostructures are typically created through a “chemical integration” approach with one-to-one covalent bonds, and generally limited to the materials with highly similar lattice symmetry and lattice constants (thus similar electronic structures) due to lattice/processing matching requirement. Materials with substantially different structure or lattice parameters can hardly be epitaxially grown together without generating too much defects that could seriously alter their electronic properties. In contrast, van der Waals integration, where pre-formed materials are “physically assembled” together through van der Waals interactions, offers an alternative “low-energy” material integration approach (vs. the more aggressive “chemical integration” strategy). The flexible “physical assembly” approach is not limited to materials that have similar lattice structures or require similar synthetic conditions. It can thus open up vast possibilities for damage-free integration of highly distinct materials beyond the traditional limits posed by lattice matching or process compatibility requirements, as exemplified by the recent blossom in van der Waals integration of a broad range of 2D heterostructures. Here I will discuss van der Waals integration as a general material integration approach beyond 2D materials for creating diverse heterostructure (e.g., dielectric/semiconductor and metal/semiconductor) interfaces with minimum integration damage and interface traps, enabling high-performing devices (including high speed transistors, diodes, plasmonic devices) that are difficult to achieve with conventional “chemical integration” approach.

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