Moir\'e quantum well states in tiny angle two dimensional semi-conductors

TL;DR

This paper demonstrates that tiny angle twist bilayers of 2D semiconductors like MoS2 and phosphorene create highly localized moiré quantum well states at the valence band edge, which can be tuned by twist angle and interlayer interaction.

Contribution

It introduces the concept of moiré quantum wells in 2D semiconductors and shows their controllability for potential quantum dot applications.

Findings

Localized energy levels form at the valence band edge due to moiré potential

Energy level spacing and number are tunable by twist angle

Charge density becomes ultra-localized at the valence band maximum

Abstract

The valence band edge in tiny angle twist bilayers of MoS$_2$ and phosphorene is shown to consist of highly localized energy levels created by a `moir\'e quantum well', i.e. trapped by the interlayer moir\'e potential. These approximately uniformly spaced energy levels exhibit a richly modulated charge density, becoming ultra-localized at the valence band maximum. The number and spacing of such levels is controllable by the twist angle and interlayer interaction strength, suggesting the possibility of `moir\'e engineering' ordered arrays of quantum dots in 2d twist semi-conductors.