Field-effect transistors are the tiny engines behind modern electronics, and one of their most important performance measures is transconductance: how effectively a change in gate voltage controls the current flowing through a channel. High transconductance can translate into greater voltage gain, faster switching and broader operating bandwidth. Now, researchers have reported a monolayer molybdenum disulfide transistor that reaches a transconductance of 0.45 millisiemens per micrometre while operating with an equivalent oxide thickness of approximately 1 nanometre, a result that addresses one of the central challenges facing ultra-scaled two-dimensional electronics.
The work, published in Nature Electronics, focuses on a top-gate field-effect transistor made from a single atomic layer of molybdenum disulfide, commonly known as MoS₂. Two-dimensional semiconductors such as MoS₂ are attractive for future electronics because their atomically thin channels offer excellent electrostatic control and could allow devices to be scaled beyond the limits of conventional silicon architectures. Yet their extreme thinness also makes them unusually sensitive to the materials placed next to them, particularly the insulating layers used to control the channel.
A transistor’s transconductance depends on several factors that are difficult to improve at the same time. A shorter channel generally increases current modulation and speed, while a thinner effective gate dielectric strengthens the electric field produced by the gate. At the same time, the semiconductor must preserve high carrier mobility, allowing electrons to move through the channel efficiently. In practice, aggressive dielectric scaling often damages mobility because defects, roughness, trapped charges and vibrational interactions in the insulator can scatter carriers in the two-dimensional semiconductor.
The researchers addressed this trade-off through an interface engineering strategy rather than simply depositing a high-κ dielectric directly onto MoS₂. High-κ materials, such as hafnium oxide, can provide strong gate control without requiring a physically thick insulating layer. Their electrical effect is described using equivalent oxide thickness, or EOT, which expresses the gate-control capability of a dielectric as the thickness of an equivalent layer of silicon dioxide. An EOT near 1 nanometre represents an intensely scaled electrostatic environment, but achieving it without introducing additional scattering is technically demanding.
To construct a cleaner interface, the team first grew an epitaxial aluminium film directly on the MoS₂ surface under ultrahigh-vacuum conditions. Epitaxy refers to the growth of a crystalline layer with a defined structural relationship to the underlying material. This approach can produce a more ordered interface than a conventional deposition process, potentially reducing the irregularities that interfere with carrier transport. The aluminium was then oxidized in situ at low pressure, forming an aluminium oxide layer derived from the epitaxial film.
That aluminium oxide interfacial layer played a critical role in the device architecture. It provided a controlled transition between the atomically thin semiconductor and the thicker insulating stack, supporting the subsequent uniform integration of hafnium oxide. Instead of exposing MoS₂ directly to a potentially disruptive high-κ dielectric, the researchers created an engineered interface designed to minimize disorder and electrostatic fluctuations near the channel. The result was a gate dielectric system capable of combining strong capacitance with a comparatively gentle environment for charge carriers.
In a top-gate transistor, the gate electrode sits above the semiconductor and modulates the density of carriers in the channel through the insulating layer. When the dielectric is thin in equivalent electrical terms, a small change in gate voltage can produce a strong change in channel charge. This improves the transistor’s ability to amplify signals and switch between conducting and non-conducting states. The challenge is that the same proximity that improves electrostatic control can also make carriers more vulnerable to imperfections in the dielectric. The reported interface was designed to capture the first benefit while suppressing the second.
The resulting MoS₂ transistors achieved a transconductance of 0.45 mS µm⁻¹ at an EOT of around 1 nm, while avoiding a notable degradation in mobility. That combination is significant because high transconductance is often obtained by sacrificing transport quality, or high mobility is preserved only by using a thicker and less powerful gate dielectric. The reported performance suggests that epitaxial interface engineering can decouple these competing requirements, at least within the demonstrated device platform.
The findings could influence the development of high-performance electronics based on two-dimensional semiconductors, including compact amplifiers, radio-frequency circuits and energy-efficient switching devices. MoS₂ remains especially interesting because it is a semiconductor with a finite bandgap, unlike graphene, which lacks a natural bandgap suitable for conventional digital switching. However, turning laboratory-scale two-dimensional devices into practical technologies will require further progress in contact resistance, large-area material growth, device uniformity and manufacturing compatibility. A carefully controlled dielectric interface may become one of the most important pieces of that puzzle.
More broadly, the study demonstrates that transistor scaling is not only a matter of making layers thinner. At nanometre dimensions, the atomic structure and chemical history of every interface can determine whether a device becomes faster or less reliable. By growing aluminium epitaxially on MoS₂ and converting it into an interfacial oxide before adding hafnium oxide, the researchers created a gate stack that combines near-nanometre electrostatic scaling with preserved carrier transport. The result offers a route toward two-dimensional transistors that are not merely smaller, but electrically more capable.
Subject of Research: Monolayer molybdenum disulfide top-gate field-effect transistors and epitaxial dielectric interface engineering
Article Title: High-transconductance molybdenum disulfide top-gate transistors using epitaxial interface engineering
Article References: Su, YC., Mao, PS., Shih, CY. et al. High-transconductance molybdenum disulfide top-gate transistors using epitaxial interface engineering. Nat Electron (2026). https://doi.org/10.1038/s41928-026-01672-7
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41928-026-01672-7
Keywords: molybdenum disulfide, MoS₂, two-dimensional semiconductors, field-effect transistors, transconductance, high-κ dielectrics, hafnium oxide, aluminium oxide, epitaxial interface engineering, equivalent oxide thickness
