MoS2 is the semiconductor material widely tipped to succeed silicon, and making a uniform monolayer film across an entire wafer has long been the sticking point. Researchers from Japan's NIMS and the University of Tokyo have now deposited a film three atoms thick across a full two-inch wafer.

Silicon's Limits and the Quest for Next-Generation Semiconductors

Semiconductor miniaturization has followed Moore's Law for decades, but conventional silicon-based technology is approaching fundamental physical limits. At today's cutting-edge 2-3nm process nodes, transistor channels are only a few nanometers thick, making quantum tunneling effects and leakage currents increasingly problematic.

Major semiconductor companies like TSMC, Intel, and Samsung are accelerating research into alternative materials for the post-silicon era of the 2030s and beyond. The leading candidates are two-dimensional materials known as transition metal dichalcogenides (TMDs).

What Is Molybdenum Disulfide (MoS2)?

MoS2 (molybdenum disulfide) is a representative TMD material. A monolayer of MoS2 consists of a layer of molybdenum (Mo) atoms sandwiched between two layers of sulfur (S) atoms, a sandwich roughly 0.65nm thick, or three atoms.

Traditionally, MoS2 has been used industrially as a lubricant. Its layered structure, held together by weak van der Waals forces between layers, allows the layers to slide easily, resulting in a low friction coefficient. However, researchers recently discovered that when reduced to a monolayer, this material becomes a direct bandgap semiconductor with excellent electrical properties.

Monolayer MoS2 has a bandgap of approximately 1.8eV and combines a high on/off ratio with good electron mobility, well suited to next-generation ultra-low-power devices.

A Technical Breakthrough Through Industry-Academia Collaboration

On January 21, 2026, a research group led by Yoshiki Sakuma, NIMS Distinguished Researcher at the National Institute for Materials Science (NIMS), and Professor Kosuke Nagashio from the University of Tokyo's Graduate School of Engineering published their results in Nature Communications. The collaborative research included Nagoya University, the University of Tsukuba, and semiconductor equipment giant Tokyo Electron Technology Solutions.

The research team discovered two critical mechanisms when growing monolayer MoS2 using metalorganic chemical vapor deposition (MOCVD):

Self-alignment mechanism: MoS2 crystal grains growing on sapphire substrates spontaneously align their crystal orientations as they merge, ultimately forming a single crystal.

Self-limiting mechanism: Using uniquely selected precursors (source gases), the deposition reaction automatically stops at monolayer thickness.

Through the synergistic effect of these two mechanisms, the team achieved uniform and reproducible epitaxial growth of monolayer MoS2 across entire 2-inch sapphire wafers.

Quality Verification: Electron Mobility Evaluation

The researchers evaluated film quality through temperature-dependent electron mobility measurements. In high-quality semiconductors, lower temperatures reduce lattice vibrations (phonons), suppressing electron scattering and increasing mobility. In contrast, materials with many defects show defect-dominated scattering, limiting mobility improvements even at low temperatures.

Measurements confirmed that MoS2 films produced by this method showed significantly improved mobility at lower temperatures, demonstrating extremely low defect density and confirming the formation of high-quality single-crystal films.

The Technology Industry Has Been Waiting For

What makes this achievement significant is its "wafer-scale" nature. While laboratory methods like mechanical exfoliation (the "scotch tape method") can produce high-quality monolayer MoS2, they only yield micrometer-sized flakes, completely unsuitable for large-scale integrated circuit manufacturing.

The semiconductor industry has established processes for forming uniform thin films on large-diameter wafers (200-300mm) and batch-processing thousands to tens of thousands of chips simultaneously. While this research uses 2-inch (approximately 50mm) wafers, it demonstrates uniform film formation across entire wafers using MOCVD, a method compatible with industrial manufacturing processes.

Tokyo Electron's participation in this collaborative research underscores the high expectations for industrializing this technology.

The Path to Sub-1nm Node Transistors

Volume production has already moved to the 2nm node: TSMC began mass production of N2 in the fourth quarter of 2025, with the 1.6nm A16 node next in line. (A16 was originally slated for volume production in late 2026; at its April 2026 technology symposium TSMC said the ramp now depends on customer products and is expected in 2027.) Beyond that sit the sub-1nm nodes.

At sub-1nm nodes, transistor channel thickness reaches extreme limits where conventional silicon cannot suppress electron tunneling. Monolayer MoS2, functioning as a semiconductor at just 0.65nm thick, emerges as a leading candidate material for realizing sub-1nm node logic transistors.

Remaining Challenges and Future Outlook

Several obstacles stand between this result and commercial production.

The first is wafer size: scaling up to the 300mm wafers that are standard in industry. Interface control between MoS2 and metal electrodes, p-type as well as n-type devices, and integration with existing CMOS lines all remain open.

However, the discovery of the "self-alignment" and "self-limiting" mechanisms provides essential foundational technology for addressing these challenges. The research group states that this achievement will significantly contribute to future large-scale integrated circuits, low-power electronics, and optoelectronic device applications.

Japan's Materials Science Leading the World

Japan's presence in the semiconductor industry has faded in recent years, but in materials and manufacturing equipment, the unglamorous layers beneath the chip, it still ranks among the best in the world. The line-up behind this result, a national research institute, universities and an equipment maker sharing one paper, shows exactly where that strength survives.

Post-silicon materials research could shape where the semiconductor industry goes next, and Japan is steadily building its position in it. What work on next-generation semiconductor materials is happening in your country?

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