Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2

TL;DR

This study demonstrates how inversion domain boundaries in MoSe2 bilayers induce diverse stacking sequences, affecting electronic properties like bandgaps, which could aid in designing tunable 2D multilayer materials.

Contribution

It introduces a method to create and analyze diverse stacking orders in MoSe2 bilayers via inversion domain boundaries, revealing their impact on electronic structure.

Findings

Diverse stacking sequences observed and characterized.

A linear relation between interlayer distance and stacking energy.

Stacking-dependent bandgap variations measured by spectroscopy.

Abstract

Interlayer rotation and stacking were recently demonstrated as effective strategies for tuning physical properties of various two-dimensional materials. The latter strategy was mostly realized in hetero-structures with continuously varied stacking orders, which obscure the revelation of the intrinsic role of a certain stacking order in its physical properties. Here, we introduce inversion-domain-boundaries into molecular-beam-epitaxy grown MoSe2 homo-bilayers, which induce unusual-fractional lattice translations to their surrounding domains, accounting for the observed diversity of large-area and uniform stacking sequences. Unusual low-symmetric stacking orders were observed using transmission electron microscopy and detailed geometries were identified by density functional theory. A linear relation was also revealed between interlayer distance and stacking energy. These stacking sequences yield various energy alignments between the valence states at {\Gamma} and K, showing stacking dependent bandgaps and valence band tail states in the measured scanning tunneling spectroscopy. These results may benefit the design of two-dimensional multilayers with manipulable stacking orders.