Exciton Emission in Molybdenum Telluride Homobilayers with Fine‐Tuned Twist‐Angles

Abstract

AbstractLayered 2H‐molybdenum ditelluride (MoTe2) is a promising near‐infrared material with optical activity, which enables hybrid‐integrated with silicon photonics for communication purposes. The use of various artificial hetero‐stacking or twist‐stacking techniques can further expand the emission bandwidth and offer more choices of optical‐active materials used as building blocks in on‐chip optoelectronic devices. However, while the twisting technique is an effective tool for adjusting interlayer interaction in van der Waals materials, a systematic experimental study of twisted MoTe2 homobilayers is currently lacking. Here, a series of MoTe2 homobilayers were prepared with precisely controlled twist‐angles from 0° to 60°, with a particular focus on the small‐twist region. Conducting photoluminescence measurements at low temperatures enabled observation of the evolution of exciton emission as the twist angle increases. Neutral and charged excitons were also identified in a dual‐gated 1.4° twisted MoTe2 through gate‐dependent and field‐dependent photoluminescence measurements. Furthermore, spatially‐resolved photoluminescence measurements revealed the critical role of the interface conditions, including interlayer spacing and strain, in addition to the twist‐angle, in determining the excitonic behavior of the material. This study provides compelling experimental evidence for understanding the twist‐angle‐dependent excitonic behaviors in atomically thin semiconductors.