Metallic Atomically-Thin Layered Silicon
March 7, 2017 | London Centre for NanotechnologyEstimated reading time: 2 minutes
A new metallic silicon (Si) nanostructure has been discovered by researchers from the London Centre for Nanotechnology, the Japan Advanced Institute of Science and Technology (JAIST), and the Brookhaven National Laboratory (BNL), USA. Their study, which appears in the journal 2D Materials ("Metallic atomically-thin layered silicon epitaxially grown on silicene/ZrB2"), shows that a new atomically-thin Si nanostructure with metallic properties can be grown upon the two-dimensional (2D) material silicene on zirconium diboride (ZrB2).
Scanning tunnelling microscopy (STM) topographic image of the silicene surface on ZrB2 with (right) and without (right) an additional layer of silicon deposited on top. A schematic illustration of this is shown above. With the added layer, the silicon nanostructure becomes metallic and forms an atomically sharp boundary with the neighbouring silicene.
The new Si nanostructure is found to form an atomically-sharp edge with the 2D silicene sheet and could enable the development of native electrical contacting, an important step to realising functional devices based upon silicene and other 2D materials.
As the size of conventional semiconductor devices approaches the fundamental limit at the atomic scale, quantum mechanical effects begin to dominate their behaviour. Researchers across the globe are working to find new ways to harness these quantum phenomena, particularly in new materials in which their effects are more pronounced. One avenue of promise is research into materials that are only a few atomic layers thick. The first of these so called “atomically-thin 2D materials” to be realised in a laboratory was graphene, which is a single layer of carbon atoms. Since the discovery of graphene, a wide range of other 2D materials have been found that have a broad array of potentially novel properties.
“One very exciting new material is silicene, the silicon analogue to graphene” says Yukiko Yamada-Takamura, the member of the research team whose group first discovered the formation of silicene on ZrB2. “Silicene is an interesting development in the field because it may give us access to the electronic properties previously unique to graphene, but in the material of choice in the information technology industry, silicon.”
Recent work has shown that silicene can be incorporated into a conventional field effect transistor and other 2D materials. However, a challenge that remains is how to precisely electrically contact external wires to the silicene sheet without destroying the electronic properties that we desire.
In this work, the researchers found that growing additional silicon layers on top of the silicene surface led to the development of an unusual form of silicon that is unlike a normal silicon crystal. Using angle resolved photoelectron spectroscopy, a technique that probes how electrons are bound in a material, the team showed that the new Si nanostructure is metallic. Scanning tunnelling microscopy, an instrument capable of observing individual atoms on a surface, was then used to show that the transition to this metallic state occurs at atomically sharp boundaries, without affecting the properties of the neighbouring silicene sheet.
“This work highlights the unexpected and intriguing results that can manifest when the structure of 2D materials are altered, even by the addition of one more layer of atoms” said Dr Tobias G. Gill, the first author of this work. “We hope that this new metallic form of silicon can be used to develop the ability to produce native electrical contacts to silicene in future devices.”
Suggested Items
SEMICON Europa 2024 Call for Abstracts Opens
05/21/2024 | SEMISEMI Europe announced the opening of the Call for Abstracts for SEMICON Europa 2024, to be held November 12-15 at Messe München in Munich, Germany. Selected speakers will share their expertise at the Advanced Packaging Conference (APC), Fab Management Forum (FMF), MEMS & Imaging Sensors Summit and during presentations on the show floor.
Material Insight: The Dielectric Constant of PCB Materials
05/17/2024 | Dr. Preeya Kuray -- Column: Material InsightIn the world of PCB design, miniaturization can be achieved by using low dielectric constant (Dk) materials. Low Dk materials can allow for a reduction in thickness while maintaining a given trace width, leading to lower transmission loss and higher density circuitry.
IPC APEX EXPO: Some Thoughts About Growth
05/16/2024 | Dan Feinberg, I-Connect007After two and a half days of wandering the aisles at IPC APEX EXPO 2024, for the first time, I almost felt like I was exploring CES. There were so many booths and exhibits that I could describe, but I’d like to focus on the growth and huge value of this event, which has expanded well beyond just the growing and impressive exhibit show floor.
The Shaughnessy Report: Unlock Your High-speed Material Constraints
05/15/2024 | Andy Shaughnessy -- Column: The Shaughnessy ReportThe world of PCB materials used to be a fairly simple one. It was divided into two groups: the “traditional” laminates, often called FR-4, and the high-speed laminates developed especially for high-speed PCBs. These were two worlds that usually didn’t collide. But then traditional laminates started getting better, and high-speed designers and design engineers took notice and started to reconsider what FR-4 could be used for.
Breaking High-speed Material Constraints: Design007 Magazine — May 2024
05/14/2024 | I-Connect007 Editorial TeamDo you need specialty materials for your high-speed designs? Maybe not. Improvements in resins mean designers of high-speed boards can sometimes use traditional laminate systems instead of high-speed materials, saving time and money while streamlining the fab process. In the May 2024 issue of Design007 Magazine, our contributors explain how to avoid overconstraining your materials when working with high-speed boards.