Abstract 

We investigated an epitaxial strategy for fabricating MoS2 light-emitting diodes (LEDs). A full-coverage MoS2 active layer was grown on p-type GaN, and n-type ZnO nanorods were then vertically aligned on the MoS2 to form ap–n junction with negligible damage to the MoS2. All materials have nearly matched hexagonal structures, enabling single-crystal alignment. Although the continuous MoS2 film formed multiple layers (MLs), the ZnO/MoS2/GaN heterostructure yielded favorable optical characteristics of the ML-MoS2, including internal quantum efficiency comparable to that of the single-layer MoS2. The ZnO/MoS2/GaN LED exhibited stable A and B exciton emissions, which implies direct bandgap transition with spin–orbit coupling. Without mechanically exfoliated or transferred 2D films, this epitaxial approach satisfies the key requirements for fabricating 2D-based optoelectronic and quantum light sources. The strength of epitaxy, such as large-scale scalability and multiple quantum-well formation, will further advance 2D optoelectronics, making them more practical and efficient.

A research team, affiliated with UNIST has demonstrated a new way to produce light-emitting diodes (LEDs) using atomically thin layers of molybdenum disulfide (MoS2). By growing the material directly on a substrate, they eliminate the need for transferring fragile 2D films—a step that has limited previous efforts to scale and uniformity.

Led by Professor Kunook Chung  from the Graduate School of Semiconductor Materials and Devices Engineering, the team developed a process to grow high-quality MoS₂ directly on gallium nitride (GaN), then add zinc oxide (ZnO) nanorods on top to form a complete p–n junction. This approach simplifies manufacturing and results in consistent, scalable devices.

MoS2, a 2D semiconductor capable of emitting visible light at just a few atomic layers, has long promised applications in quantum light sources and integrated photonics. However, traditional fabrication methods involve synthesizing the material separately and then transferring it onto a substrate, which often introduces defects, contamination, and variability.

By growing MoS2 directly on GaN, the team avoided these issues. The process begins with depositing GaN, then carefully epitaxially growing MoS2 at high temperature. The ZnO nanorods are subsequently grown vertically on the MoS₂ layer, creating a well-aligned, high-quality heterostructure.

These devices emit red light at wavelengths of 630 nm and 705 nm, confirmed through optical testing. The emission features quantum effects like spin–orbit coupling, suggesting potential for quantum photonic applications.

Professor Chung explained, “Transfer processes have limited the scalability of 2D LEDs. Our method shows that direct growth can produce uniform, high-quality devices—similar to traditional semiconductor fabrication. This opens the door to large-scale, practical 2D optoelectronics.” He further added, “Further improvements in efficiency could lead to applications such as micro-LED displays or quantum light sources, especially in the red spectrum.”

The findings of this research have been featured as the Supplementary Cover of Nano Letters on April 21, 2026. The study has been supported by the National Research Foundation of Korea (NRF), the Ministry of Science and ICT (MSIT), the Korea Institute for Advancement of Technology (KIAT), and the Ministry of Trade, Industry, and Resources (MOTIE).

Journal Reference

Imasda Rahmatulloh, Daryll JC Dalayoan, Asad Ali,  et al ., “Epitaxial n-ZnO/MoS2/p-GaN Heterostructure Light-Emitting Diodes,”   Nano Letters,  (2026).