Duan Research Group

Hetero-integrated Nanostructures and Nanodevices


Van der Waals superlattices

Huaying Ren, Zhong Wan, Xiangfeng Duan

National Science Review (2022)

Semiconductor technology has enabled many essential devices, including transistors for computing and communication, diodes for solid-state lighting and photovoltaics. Behind all these devices, the material foundation is a series of highly elaborated heterostructures and superlattices [1]. To this end, integrating different materials into heterostructures or superlattices with well-defined spatial modulation of chemical compositions and electronic structures is central for generating designed electronic functions and has been a continued pursuit of the materials science community. The traditional approaches to heterostructures and superlattices, such as epitaxial growth, usually rely on the atom-to-atom covalent bonds to join the constituent materials and are often limited by strict lattice matching or processing compatibility requirements. High-quality heterostructures or superlattices can only be obtained between materials with nearly identical lattice structures and thus very similar electronic properties (e.g. Ga1−xAlxAs with slightly different compositions) [2]. A slight mismatch would inevitably lead to interfacial defects/strains, which could often propagate well beyond the interface to form extensive dislocations in bulk lattices, and in some cases, totally disordered interfacial layers (Fig. 1a and b) [3]. As a result, materials with substantially different lattice structures can hardly be integrated together without generating too many defects that may fundamentally alter their electronic functions.
UCLA, Department of Chemistry and Biochemistry
607 Charles E. Young Drive East, Box 951569
Los Angeles, CA 90095-1569
E-mail: xduan@chem.ucla.edu