Manipulating Wrinkles Could Lead to Graphene Semiconductors
October 23, 2015 | RIKENEstimated reading time: 2 minutes
Graphene has generally been described as a two-dimensional structure—a single sheet of carbon atoms arranged in a regular structure—but the reality is not so simple. In reality, graphene can form wrinkles which make the structure more complicated, potentially being applied to device systems. The graphene can also interact with the substrate upon which it is laid, adding further complexity. In research published in Nature Communications, RIKEN scientists have now discovered that wrinkles in graphene can restrict the motion of electrons to one dimension, forming a junction-like structure that changes from zero-gap conductor to semiconductor back to zero-gap conductor. Moreover, they have used the tip of a scanning tunneling microscope to manipulate the formation of wrinkles, opening the way to the construction of graphene semiconductors not through chemical means—by adding other elements—but by manipulating the carbon structure itself in a form of “graphene engineering.”
The discovery began when the group was experimenting with creating graphene films using chemical vapor deposition, which is considered the most reliable method. They were working to form graphene on a nickel substrate, but the success of this method depends heavily on the temperature and cooling speed.
According to Hyunseob Lim, the first author of the paper, “We were attempting to grow graphene on a single crystalline nickel substrate, but in many cases we ended up creating a compound of nickel and carbon, Ni2C, rather than graphene. In order to resolve the problem, we tried quickly cooling the sample after the dosing with acetylene, and during that process we accidentally found small nanowrinkles, just five nanometers wide, in the sample.”
They were able to image these tiny wrinkles using scanning tunneling microscopy, and discovered that there were band gap openings within them, indicating that the wrinkles could act as semiconductors. Normally electrons and electron holes flow freely through a conductor without a band gap, but when it is a semiconductor there are band gaps between the permitted electron states, and the electrons can only pass through these gaps under certain conditions. This indicates that the graphene could, depending on the wrinkles, become a semiconductor. Initially they considered two possibilities for the emergence of this band gap. One is that the mechanical strain could cause a magnetic phenomenon, but they ruled this out, and concluded that the phenomenon was caused by the confinement of electrons in a single dimension due to “quantum confinement.”
According to Yousoo Kim, head of the Surface and Interface Science Laboratory, who led the team, “Up until now, efforts to manipulate the electronic properties of graphene have principally been done through chemical means, but the downside of this is that it can lead to degraded electronic properties due to chemical defects. Here we have shown that the electronic properties can be manipulated merely by changing the shape of the carbon structure. It will be exciting to see if this could lead to ways to find new uses for graphene.”
Suggested Items
Walmart Acquires Vizio, Set to Overtake Samsung as the Largest TV Brand in the US
02/22/2024 | TrendForceUS retail giant Walmart announced on February 20, that it has acquired smart TV brand Vizio for US$2.3 billion, aiming to accelerate the growth of its advertising business: Walmart Connect. Since its launch in 2021, Walmart Connect has seen double-digit annual growth in both its online and offline retail media advertising ventures. Vizio has been expanding its device ecosystem and its SmartCast TV OS, boasting over 18 million active users, according to TrendForce.
Fiber Optic Cables Effective Way to Detect Tsunamis
02/16/2024 | University of MichiganFiber optic cables that line ocean floors could provide a less expensive, more comprehensive alternative to the current buoys that act as early warning systems for tsunamis, says a University of Michigan researcher.
EIPC Winter Conference 2024, Day 2: A Closer Look at Global Trends
02/14/2024 | Pete Starkey, I-Connect007The opening session of the second day’s conference proceedings focused on global PCB trends and was introduced and moderated by Dr. Michele Stampanoni, vice president of strategic sales and business development at Cicor Group in Switzerland. He opened the session with Dr. Hayao Nakahara’s knowledgeable and enlightening video presentation on the IC substrates industry.
IDTechEx Discusses Whether Fuel Cell Vehicles Will Succeed and What It Would Take
02/12/2024 | PRNewswireThe sales of hydrogen fuel cell cars have largely stalled from 2021 onwards, but does this mean there is no market for fuel cell electric vehicles (FCEVs) in the future, and what is required to make them a success? IDTechEx's report, "
Electronics Industry Mourns Loss of Colleague and Visionary Michael Ford
01/31/2024 | I-Connect007Sadly, longtime I-Connect007 columnist, industry visionary, and friend Michael Ford passed away Jan. 27. “In this time of sorrow, we can take solace in the knowledge that Michael leaves a great legacy of contribution to the electronics industry,” according to a statement from Aegis Software. Michael was senior director of emerging industry strategy at Aegis. He was a prolific writer and speaker whose work and ideas put him at the forefront of electronics manufacturing. Working for Aegis gave him the opportunity to apply his software for electronics manufacturing experience to further drive technology solution innovation.