Engineers solved a stubborn interface problem that has held back atomically thin transistors for years, achieving both thin insulating layers and strong electron flow.
For more than a decade, atomically thin semiconductors have been seen as a promising route beyond conventional silicon. These materials, just a single atom thick, offer impressive electrical properties. In principle, they could enable transistors that are smaller, faster, and more energy efficient than today's devices. But a stubborn engineering problem has remained.
A working transistor requires an extremely thin insulating layer — the gate dielectric — that sits above the semiconductor and helps control electron movement. As transistors shrink, making this layer thinner improves electrical control. But adding such layers to atomically thin semiconductors can disturb the delicate interface between materials, scattering electrons and erasing the performance gains.
Researchers at National Yang Ming Chiao Tung University (NYCU), working with TSMC Corporate Research, have now demonstrated a new approach. Instead of searching for a better semiconductor or a different dielectric, they focused on the narrow region where the two materials meet — an area only a few atoms thick.
The team placed an ultrathin epitaxial aluminum layer directly onto monolayer molybdenum disulfide (MoS₂), then carefully oxidized the aluminum to produce an aluminum oxide layer about 0.42 nanometers thick. After that, they added the hafnium oxide gate dielectric.
The engineered interface performs two jobs simultaneously. It creates a smooth, continuous surface that allows the dielectric to grow uniformly, and it works as an atomic buffer that limits unwanted electrical interactions, helping electrons continue moving efficiently through the transistor channel.
Using the new interface design, the researchers fabricated short-channel top-gate transistors with an equivalent oxide thickness of roughly one nanometer. The devices showed low leakage current, minimal hysteresis, and strong transconductance — a combination that has been difficult to achieve in atomically thin transistors.
Because the team used CVD-grown monolayer MoS₂ rather than mechanically exfoliated flakes, the approach is compatible with materials and processes that could eventually be suitable for wafer-scale manufacturing.
The findings point to a broader change in semiconductor design. For decades, improving transistors meant finding better materials or making devices smaller. As components approach atomic dimensions, the interfaces separating different materials become increasingly important. These regions may be only a few atoms thick, yet they strongly influence how well the materials on either side work together.
As the semiconductor industry looks for ways to continue improving chips beyond traditional silicon scaling, learning to engineer these atomic interfaces with precision could become as important as discovering new materials themselves.