Scientists have discovered a new method to produce high-quality semiconductor films at lower temperatures, potentially simplifying the development of next-generation AI chips, ultra-low-power electronics, and advanced optical devices.
Led by Professor Joonki Suh at the Korea Advanced Institute of Science and Technology (KAIST), along with researchers from Hanyang University in South Korea and Rice University in the U.S., the study was recently published in Science Advances.
Modern electronics often depend on stacking different materials, each serving a specific purpose. To ensure these layered structures operate efficiently, engineers must assemble them carefully, avoiding damage or defects at the interfaces. Even minor imperfections at these junctions can impair device performance.
A promising class of materials gaining attention is van der Waals materials, composed of ultra-thin atomic layers that are loosely connected. This characteristic allows different materials to be stacked like sheets of paper without contaminating their surfaces, making them highly suitable for future semiconductor applications, especially in AI and energy-efficient devices.
However, a significant obstacle has been the chemically stable surfaces of van der Waals materials, which hinder the organized growth of new semiconductor layers. This challenge intensifies at lower temperatures, where atoms tend to settle randomly instead of aligning with the existing crystal lattice. Such uncontrolled growth compromises the quality and efficiency of the resulting devices.
To overcome this, the researchers improved atomic layer deposition (ALD)—a process that constructs ultra-thin films one atomic layer at a time. Their modified method allows tellurium-based molecules, or precursors, to move freely over the surface before bonding. This mobility grants the molecules time to find the most stable positions, encouraging the formation of orderly, crystalline structures rather than disorganized layers.
Tellurium was chosen because of its excellent electrical and optical properties, including anisotropic conductivity and strong interaction with light—attributes useful for photodetectors, LEDs, and advanced semiconductor components. Using this approach, the team successfully grew tellurium films with single-crystal orientation at just 150°C (302°F) through a process called epitaxy, where the new layer aligns with the underlying crystal structure—similar to stacking bricks neatly in straight lines. Such orderly growth improves electrical flow and device performance.
The team demonstrated this technique’s versatility by applying it to various van der Waals materials, including tungsten diselenide, molybdenum disulfide, rhenium diselenide, and mica. This indicates the method’s potential broad applicability.
To showcase practical benefits, they fabricated transistors and optoelectronic devices using the newly grown films, demonstrating their ability to control, detect, and emit light. This highlights the method’s promise not just for laboratory research but also for manufacturing high-quality electronic components.
Professor Suh noted that this is the first time high-quality semiconductor films have been grown on van der Waals materials at low temperatures without harming the layers underneath. This innovative process could serve as a foundational platform for integrating diverse next-generation materials onto single chips, paving the way for faster, more efficient electronic devices in the future.