Coherent Quantum Transport in Monolayer Semiconductors Achieved

In a groundbreaking study, researchers have successfully integrated monolayers of molybdenum disulfide (MoS₂) into field-effect transistor (FET) arrays, showcasing advanced electronic properties that could pave the way for more efficient semiconductor technologies. This innovative approach utilizes vicinal van der Waals epitaxy, a method that has allowed for the seamless transfer of these single-crystalline materials onto a hafnium oxide (HfO₂)/p⁺-silicon substrate. The implications of this work are substantial, as it not only enhances device performance but also offers a pathway for developing next-generation electronic components.

The FETs in these arrays have been constructed without the passivation layer of hexagonal boron nitride (hBN), which is often considered a reliable insulating layer in various applications. The omission of this layer was a strategic choice, emphasizing practical scalability in production while achieving optimal performance in real-world conditions. Notably, the research team managed to create ohmic contacts using bismuth as the source and drain, which was confirmed through the measured current-voltage (I-V) characteristics of the devices.

One of the standout features of the FETs is their transfer characteristics, showcasing an extraordinary sharp subthreshold swing (SS) of 65 mV per decade at room temperature. This characteristic represents a significant achievement as it approaches the theoretical limit of 60 mV per decade, which is crucial in determining the performance efficiency of transistors. Furthermore, the on/off current ratio of these devices exceeds 10⁷, underlining their applicability in advanced digital applications where low power consumption and high operational speed are essential.

Statistics gathered from the analysis of 64 individual FETs within the array illustrate an average field-effect mobility (μ_FET) of approximately 100 cm²V⁻¹s⁻¹, establishing performance metrics that surpass those achieved in previous demonstrations of epitaxial MoS₂ monolayers. This impressive mobility is attributed to the superior quality of the single-crystal MoS₂ monolayers, which, in turn, is a result of the efficient epitaxial growth technique employed in the study.

The research also delves into the statistical distribution of SS and mobility across the devices, highlighting that the devices maintained an SS range between 65 and 75 mV per decade. This spread showcases the consistency and reliability of the fabrication method, essential traits for commercial applications. Remarkably, this work outperformed earlier examples of epitaxial MoS₂ that employed similar growth techniques, which reported lower mobilities and higher SS values.

The impressive SS value presented in this study can greatly be linked to the reduced density of defects in the MoS₂ monolayers. Defect states often create charge traps that adversely affect the electronic characteristics of semiconductors, leading to non-ideal transistor behaviors such as increased SS values. By minimizing these defects through advanced growth techniques, the researchers have not only improved device performance but also derived deeper insights into the fundamental physics of material properties.

Previous advancements have already explored the epitaxial growth of MoS₂ single crystals on substrates such as c-plane sapphire, indicating an ongoing interest in exploiting various substrate materials to tailor electronic properties. Studies documenting average μ_FET values of about 78 cm²V⁻¹s⁻¹ and higher SS values around 120 mV per decade emphasize the progressive evolution of this field. The comparative analysis with this newer work signifies the continual stairway of innovation leading towards the realization of more efficient two-dimensional electronic devices.

The implication of such findings heralds a new chapter in semiconductor research, particularly for applications requiring low power and high scalability. Considering the growing demands for more efficient electronic components capable of operating at faster speeds with reduced power requirements, this innovative research provides a foundation for future development. The integration of MoS₂ into FET arrays, with its optimal performance innovations, demonstrates a plausible route to overcoming existing challenges in semiconductor technology.

The current approach not only addresses previous limitations seen in two-dimensional material utilization but also enhances the potential for implementing these advanced devices in real-world scenarios. With increasing emphasis on sustainable and efficient technologies, the advancements reported hold promise for a myriad of applications in automotive, consumer electronics, and beyond.

Moreover, this recent work underscores the significance of material quality in the performance of electronic components. As researchers continue to explore the intersections of material science and electronic engineering, the insights gleaned from this study can help to inform future innovations and lead to even higher performance thresholds.

Ultimately, the forward strides made in this research signify an important milestone in materials science and semiconductor physics. With a focus on achieving coherence in quantum transport within single-crystalline structures via effective epitaxy, there remains significant potential for exciting breakthroughs in technology development. These findings not only expand the knowledge surrounding two-dimensional materials like MoS₂ but also spark curiosity about the vast possibilities that lie ahead in this rapidly advancing field of study.

The researchers’ efforts exemplify the interdisciplinary nature of modern scientific inquiry, blending aspects of physics, engineering, and nanotechnology to achieve groundbreaking results. As we move forward, the need for efficient and scalable semiconductor technologies becomes increasingly imperative, and studies like these provide the necessary groundwork for realizing that vision.

In conclusion, the integration of single-crystalline MoS₂ in FET arrays represents a significant engineering achievement. It illustrates the incredible potential of these materials within the electronics landscape, shaping the future of computing and communication technologies. Continued exploration and refinement of these approaches are set to unlock further innovations, ultimately leading to more sustainable and efficient electronic devices that redefine our technological experience in the years to come.

Moon, G., Lee, SH., Cho, H. et al. Single-crystalline monolayer semiconductors with coherent quantum transport by vicinal van der Waals epitaxy.
Nat Electron (2025). https://doi.org/10.1038/s41928-025-01496-x