Controllable Formation of Zero-twisted 2D Layers via Atomic Reconstruction

Twist angle between two-dimensional (2D) layers is a critical parameter that determines their
interfacial properties, such as moiré excitons and interfacial ferroelectricity. To achieve better control
over these properties for fundamental studies and various applications, there have been considerable
efforts to manipulate the twist angle. However, due to mechanical limitations and the inevitable
formation of incommensurate regions, there remains a challenge in perfectly aligning the crystalline
orientation. This talk describes techniques and mechanisms of formation of zero-twisted transition
metal dichalcogenides multilayers by thermally induced atomic reconstruction, regardless of twist
angles of as-stacked samples and lattice mismatches. We also demonstrate the selective formation of Rand
H-type FC phases with a seamless lateral junction using chemical-vapor-deposited TMDs. The
resulting FC phases exhibit strong photoluminescence (PL) enhancement of the interlayer excitons even
at room temperature due to their commensurate structure with aligned momentum coordinates. Our
work not only shows a way to fabricate zero-twisted 2D bilayers with R and H-type configurations, but
also provides a platform for studying their unexplored properties.