Atomic sculpting; patterning 2D materials; MRI project.
Oak Ridge National Laboratory has combined a scanning transmission electron microscope (STEM) with new electronic controls. This tool enables the construction, or the atomic sculpting, of 3D-like feature sizes down to 1nm and 2nm.
To achieve these dimensions, the STEM is controlled with a special set of programmable electronics. This, in turn, enables the STEM to tunnel into non-crystalline material, thereby creating features that are in perfect alignment.
The tool can create any shape. It does this by exposing patterned areas to higher numbers of electrons.
In the lab, researchers took the STEM and developed crystalline material from non-crystalline material. “Interestingly, this non-crystalline oxide layer was made by a usually undesirable process: While preparing a sample for the electron microscope, significant re-deposition of the initially crystalline substrate occurs,” according to the U.S. Department of Energy (DOE). Oak Ridge is part of the DOE.
“This redeposited material is non-crystalline and is on top of the initial crystalline film. The electron beam can then sculpt and crystallize this non-crystalline material,” according to the DOE.
The result is materials with desirable structures. The STEM tool could be used to make integrated circuits and other products.
Patterning 2D materials
Using e-beam lithography, Oak Ridge National Laboratory has developed a process for creating 5nm junctions based on 2D materials.
Two-dimensional (2D) materials are gaining steam in the R&D labs. The 2D materials include graphene, boron nitride and the transition-metal dichalcogenides (TMDs). Two TMDs, molybdenum diselenide (MoSe2) and molybdenum disulfide (MoS2), are gaining interest in the market.
The 2D materials could enable a new class of field-effect transistors (FETs) and contacts in today’s chips, but the technology isn’t expected to appear until sometime in the next decade.
Meanwhile, in Oak Ridge’s flow, single layers of MoSe2 crystals less than a nanometer thick were first patterned using e-beam lithography. Then, the pattern was exposed to laser-vaporized sulfur.
The sulfur atoms replaced the selenium atoms in the exposed regions. This, in turn, converted MoSe2 to MoS2. Electron microscopy revealed that the junctions were only 5nm wide.
A group from Europe has been selected to join the European Union-funded IDentIFY project to extend the capability of magnetic resonance imaging (MRI) in disease detection.
The four-year IDentIFY project is coordinated by the University of Aberdeen. The other partners are CEA (led by Leti, a CEA Tech institute, and Inac), INSERM, and G2ELab.
The project, which is part of the EU Horizon 2020 program, was initiated by INSERM. It aims to further develop and help commercialize a characterization technique, called Fast Field-Cycling (FFC) MRI to obtain quantitative, diseaserelated information that is invisible to standard MRI.
Unlike standard MRI, in which scanners operate at a strong, fixed magnetic field, FFC-MRI scanners yield images of living organisms at varying low values of the magnetic field by fast switching of this field from high to near-zero values. This technique can deliver medical information at a lower cost than conventional MRI.
“This technology presents a huge opportunity to cost-effectively improve health care, especially for cancer, one of the world’s fastest-growing diseases,” said Marie Semeria, CEO of Leti, a CEA Tech institute.