Science Gazette

Wafer-scale atomically thin crystal assembly programmed


Lego bricks, which are popular with both children and adults, may be combined into set models like as space shuttles or fancy buildings, but they can also be used to construct any new constructions. A novel method for assembling atomic-sized blocks into new materials, similar to these blocks, has been presented.

A POSTECH research team led by Professor Cheol-Joo Kim and Ph.D. candidates Seong-Jun Yang and Ju-Hyun Jung (Department of Chemical Engineering) has developed a technology for assembling wafer-scale films at the atomic level in collaboration with Dr. Chang Cuk Hwang and Dr. Eunsook Lee (Pohang Accelerator Laboratory) and Professor Pinshane Y. Huang and Ph.D. candidate Edmund Han (University of Illinois The discoveries, which were just published as the front cover article of Nano Letters, are the consequence of carefully tailoring the structure of materials at the atomic level.

Crystal films made of atoms have different physical characteristics depending on how their thickness or atomic structure is modulated. The physical characteristics of these thin films vary depending on their stacking arrangement, which might be layer-by-layer or twisted. However, previous research has only allowed for the production of atomically thin crystals on a very small scale since constructing big wafer-sized thin films readily contaminates their interfaces, preventing the formation of novel features.

To solve this, the researchers suggested a van der Waals-assisted programmed crystal assembly of graphene and monolayer hexagonal boron nitride (hBN). This novel approach yields wafer-scale films with practically perfect surfaces.

The adoption of this novel approach allows for the large-scale fabrication of wafer-size artificial crystalline films, which had hitherto been impossible to employ as real devices owing to their tiny size. Because it can program the structure of a material at the atomic level, this technique has the potential to aid in the development of novel materials that produce light or conduct electricity.

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“The atomic-level assembly approach has been constrained to extremely tiny scales, restricting property discovery and technology development to mere verification at the single-device level,” said research leader Professor Cheol-Joo Kim. “The results of this work have proven for the first time the atomic-level precise assembly of single-crystalline materials at the wafer-scale, which will be useful to the creation of nanodevices in the future,” he noted.

The National Research Foundation of Korea funded this work via the Young Researcher Program and the Creative Materials Discovery Program.

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