In 2004, the researchers discovered a super-thin material that is at least 1
This means that graphene could bring faster electronics than silicon can do today.
However, to be really useful, graphene would have to carry an electrical current that turns on and off, as it does silicon the form of billions of transistors on a computer chip. This switch generates sequences of zeros and ones that a computer uses to process information.
Researchers at Purdue University, in collaboration with the University of Michigan and the Huazhong University of Science and Technology, show how a laser technique can permanently load graphene into a structure that allows the flow of electrical current.
This structure is a so-called "band gap". Electrons must jump across this gap to become conduction electrons capable of carrying electrical current. But of course Graphen has no bandgap.
Purdue researchers have increased the band gap in graphene to a record of 2.1 electron volts. To function as a semiconductor such as silicon, the band gap would have to be at least the previous 0.5 electron volt record.
"This is the first time an effort has achieved such high band gaps without affecting the graphene itself, such as chemical doping, and we've just stretched the material," said Gary Cheng, a professor of industrial engineering at Purdue University, whose laboratory has investigated various ways to make graphene more useful for commercial applications.
The presence of a band gap allows semiconductor materials Depending on whether their electrons are pushed over the band gap or not, it is possible to switch between isolation and conduction of an electrical current.
According to the researchers, more than 0.5 electron volts will release even more potential for graphene in next-generation electronic devices. Her work appears in an issue of Advanced Materials .
"Researchers have in the past opened the bandgap by simply stretching graphene, but stretching them alone does not greatly increase the bandgap. They must permanently change the shape of graphene to keep the bandgap open," Cheng said.
Cheng and his co-workers not only revealed the band gap in graphene, but also adjusted it so that the gap width could be adjusted from zero to 2.1 electron volts. Scientists and manufacturers have the option to use only certain properties of graphene , depending on what the material should do.
The researchers made the band gap structure in graphene durable by using a technique called laser shock imprint that Cheng developed in 2014 along with scientists from Harvard University, the Madrid Institute for Advanced Studies, and the University of California, San Diego.
For this study, researchers used a laser to generate shockwave pulses that penetrate an underlying graphene sheet. The laser shock spans graphene in a trench-like shape and forms it permanently. Adjusting the laser power adjusts the bandgap.
Although the technology does not yet incorporate graphene into semiconductor devices, it offers more flexibility in exploiting the optical, magnetic, and thermal properties of the material, Cheng said.
Holey graphene as a Holy Grail alternative to silicon chips
Maithilee Motlag et al., Asymmetric Elastic-Electron Stress-Modulating 3D Electron Energy Structure in Single-Layer Graphene by Laser Shock, Advanced Materials (2019). DOI: 10.1002 / adma.201900597
Laser Technology May Enable Use of Tough Material for Next Generation Electronics (2019, May 30)
retrieved on May 31, 2019
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