Revealing Intrinsic Excitonic and Interlayer Coupling in CVD-Grown TMDCs via a Bubble-Free Interface

Abstract

The integration of van der Waals (vdW) materials, especially those grown by chemical vapor deposition (CVD), is often hindered by interfacial contamination, bubble formation, and chemical damage during transfer. Here, we demonstrate an hBN-assisted encapsulation strategy that leverages the strong adhesion between hBN and CVD-grown transition metal dichalcogenides (TMDCs) to lift them cleanly from SiO2 substrates without the use of harsh chemicals. A hot inclined touch-down method applied during stacking minimizes interfacial defects and bubble formation, preserving optical integrity. This process enables the assembly of high-quality homo- and heterobilayers, such as MoS2/MoS2, WSe2/WSe2, and WSe2/MoSe2, which exhibit enhanced excitonic features and pronounced interlayer Raman modes, as well as spatially indirect excitons, confirming strong interlayer coupling. The technique is compatible with patterned or suspended substrates, thereby expanding its applicability to studies of strain and environmental effects. Our all-dry encapsulation method yields optically pristine hBN/TMDC heterostructures from CVD-grown materials, paving the way for next-generation 2D optoelectronic and quantum devices.