Hanyang Method Controls Where Semiconductor Crystals Form
Hanyang University semiconductor crystals research in Nature shows a method that achieved over 99% single-crystal growth across 400 sites.
By Academic Writing Club Newsroom
Researchers at Hanyang University have found a way to decide where semiconductor crystals begin to form, achieving over 99% single-crystal growth across 400 sites. The method, called etching-flux-mediated single-centred nucleation (EF-SCN), was described in a study published in Volume 658 of Nature on October 7, 2026. Professor Woo-Hee Kim from Hanyang University, Republic of Korea, carried out the work with colleagues from collaborating institutions. EF-SCN uses oxygen released from an oxide barrier to control the point where crystals start growing. Controlling where crystals begin to form is a challenge in manufacturing two-dimensional semiconductors.
Why Nucleation Matters
In semiconductor manufacturing, nucleation, the moment crystals first begin to form, determines where and how they grow. This is particularly important for two-dimensional (2D) semiconductors, which are promising for next-generation electronics.
Conventional area-selective growth methods cannot reliably control where crystals begin forming within designated regions. That makes it difficult to produce large single crystals and precisely aligned structures for electronic devices.
How the Oxide Barrier Works
The team grew molybdenum disulfide (MoS2), a two-dimensional semiconductor, on patterned substrates using metal-organic chemical vapor deposition. Each designated growth region was surrounded by a hafnium oxide (HfO2) barrier that releases oxygen when heated to 750°C. The oxygen etches the material near the pattern boundaries, suppressing nucleation there and favoring the formation of a single crystal at the center. As growth continues, the crystal expands outwards to form a larger single-crystal region.
The researchers showed consistent, centrally located nucleation across patterned arrays, with crystals filling their designated regions to form single-crystal domains several micrometers across. In a lower-temperature version of the method, they replaced HfO2 with zirconium dioxide, which has a lower crystallization temperature and serves as an alternative etching-flux barrier. This allowed them to grow uniform, centrally nucleated triangular single-crystal MoS₂ domains at temperatures as low as 430°C.
Tuning the Growth Conditions
The study also examined how growth conditions shape crystal formation. The flow rate of diethyl sulfide, which supplies sulfur, primarily controls the number of nuclei that form: too little can prevent nucleation, while too much can produce multiple crystals. The molybdenum precursor flow rate affects how far the crystals grow.
By adjusting these conditions and the pattern dimensions, the researchers produced large crystals and line-shaped channels suitable for transistor integration. They grew crystals approximately 8 micrometers across and single-crystal films filling 10-micrometer growth regions. Across a 2-centimeter substrate, the method achieved a single-crystal yield exceeding 99%.
From Crystals to Transistors
Woo-Hee Kim, Professor at Hanyang University, said:
“To assess the electronic properties of these crystals, our team fabricated field-effect transistors using the MoS2 grown via our EF-SCN method.”
The devices achieved a field-effect mobility of up to 117 cm2 V-1s-1. The team integrated four transistors within a single crystal, with just 7.8% variation in electron mobility, showing the potential to build denser electronic circuits with more consistent performance.
A Framework for Device Integration
The paper is titled Spatially deterministic nucleation of 2D semiconductors by etching flux.
Woo-Hee Kim, Professor at Hanyang University, reflected:
“This approach goes beyond conventional area-selective growth and enables highly reproducible single-crystal growth and provides a general framework for programming nucleation position, crystal geometry and subsequent device integration.”
