Two-dimensional (2D) semiconductors, such as atom-thin materials such as monolayer MoS₂ or MoSe₂, show strong promise for highly scaled, high-performance electronics. But a key challenge has been reliably fabricating high-quality 2D wafers and stacking them into engineered multi-layer structures with clean, controlled interfaces, tells Tech Xplore.
The research team introduced a bonding approach that places two monolayer-semiconductor wafers face-to-face, under vacuum or in a glove box, cleaning and annealing them, then pressing and bonding them without any glue-like intermediate layer. This produces a stack with ultra-clean interface, wafer-scale uniformity, and precise control of the number of layers and inter-layer twist angles.
They demonstrated this with 2-inch wafers of monolayer MoSe₂ and MoS₂, successfully bonding them into heterostructures and homostructures, and even bonding a monolayer MoS₂ directly onto high-k dielectric substrates (HfO₂, Al₂O₃) while preserving the intrinsic electronic properties of the semiconductors.
Because the method avoids adhesive interfaces, it reduces contamination and interface defects—key for achieving high device performance. Also, because the bonding process is reversible, the bonded structure can later be debonded, and the process offers flexibility in fabrication and integration.
For engineers working in advanced materials and device integration, this breakthrough offers a promising route toward stacking 2D semiconductors at scale, enabling next-generation transistors, sensors, or other components with minimal interface loss. The scalability, wafer-level uniformity, and interface cleanliness bring 2D semiconductor systems closer to practical device manufacturing. The next step will be integrating this method into full device fabrication flows and assessing the electrical/thermal reliability of the bonded stacks.