Demystifying the Art of Novel Material Crystal Growth with Diffraction
Researchers use a non-destructive CT technique to study a flux-grown layered semiconductor crystal KBiS2.
You may be surprised to know that the computing processors you use in a phone or computer are built on super-perfect arrangements of atoms, all lined up across a chip. Single crystals are the ticking hearts of these devices and consist of some of the most perfect arrangements of materials in the universe, and we carry them around without a second thought. Yet today, we only use very simple crystals like silicon for this purpose. For the next generation of devices, taking advantage of more complex materials for new functions and energy efficiency is exciting and inevitable.
Dr. Daniel Shoemaker, Associate Professor at the University of Illinois Urbana-Champaign, USA, directs research to create materials with new electronic and magnetic functions. In his recent publication, his lab uses diffraction contrast tomography with ZEISS Xradia Versa to understand the morphology and growth habits of a novel flux-grown layered semiconductor crystal, KBiS2.
Non-destructive CT Reveals Crystal Morphology and Growth
Dr. Shoemaker's lab grows a lot of large, single crystals in their effots to create materials with new electronic and magnetic functions. He describes it as a very mysterious process. These crystals form in an opaque liquid at high temperatures, so they are not easily observed during or after their formation. Opening the vessels they grow in would cause them to react with the oxygen in air.
In their publication, a non-destructive CT technique with ZEISS Xradia Versa is used to probe not just the shape of the crystals of a novel flux-grown layered semiconductor crystal, KBiS2, but also to investigate how the atomic planes in the crystals are oriented in three dimensions.
I was really shocked that we could look inside such a “messy” system and get such rich information. It was an unexpected bonus when we discovered a new type of crystalline material in the process.
Diffraction Contrast Tomography Reveals Needle-Shaped Crystals
The Benefits of Diffraction Contrast Tomography
Dr. Shoemaker explains that many might be more familiar with traditional computed tomography (CT) methods, which basically record a series of projections and reproduce the 3D shapes of things. Here they did a diffraction CT measurement, which also analyzes the orderly rays of X-rays that arise from specific atomic arrangements in crystals. Merging the diffraction data and CT data tells them the full information about not only the crystal size and shape, but also the atomic arrangements inside them.
Laue Diffraction Patterns Collected Using Lab-based Diffraction Contrast Tomography (LabDCT)
Using Diffraction for Future Studies
These experiments were conducted as a challenge to discover if a non-destructive CT technique with ZEISS Xradia Versa could reveal more information about crystal morphology and growth patterns.
Now that they have discovered it is possible, Dr. Shoemaker and his team are exploring how this technique can grow improved materials with novel functions. Topological materials and spintronic compounds are often grown from melts, but their crystallization behavior has not been imaged directly. By watching these processes unfold, they hope to identify new materials, as was accomplished for KBiS2.