New method produces graphene on surfaces for precise electronics applications

Scientists at Rice University, the University of Tennessee, Knoxville (UT Knoxville) and Oak Ridge National Laboratory (ORNL) have demonstrated the use of a very small visible beam to burn graphene into microscopic patterns.

Schematic of the method for finely creating graphene with a small laser imageScientists recorded the formation of laser-induced graphene made with a small laser mounted to a scanning electron microscope. Image credit: the Tour Group

The labs of Rice chemist James Tour, which discovered the original method to turn a common polymer into graphene in 2014, and Tennessee/ORNL materials scientist Philip Rack revealed they can now watch the conductive material form as it makes small traces of LIG in a scanning electron microscope (SEM).

Special substrates enable large single crystal bi-/tri-layer graphene growth

Researchers of the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS, South Korea), in collaboration with UNIST and Sungkyunkwan University teams, have reported the fabrication and use of single crystal copper-nickel alloy foil substrates for the growth of large-area, single crystal bilayer and trilayer graphene films.

The growth of large area graphene films with a precisely controlled number of layers and stacking order can open new possibilities in electronics and photonics but remains a challenge. This study showed an example of the synthesis of bi- and trilayer graphene sheets larger than a centimeter, with layers piled up in a specific manner, namely AB- and ABA-stacking.

New method uses hydrogen plasma to smooth out wrinkles in graphene

Researchers from Nanjing University in China have developed a method to make large graphene films free of any wrinkles. The ultra-smooth films could enable large-scale production of electronic devices that harness the unique physical and chemical properties of graphene and other 2D materials.

Wrinkles  disappear when graphene is treated with a hydrogen plasma imageWrinkles in graphene films grown via chemical vapor deposition appear as jagged white lines at the top of this atomic force microscope image (left), but they disappear when the material is treated with a hydrogen plasma (right). Credit: Nature

Chemical vapor deposition (CVD) is the best-known method for making high-quality graphene sheets. It typically involves growing graphene by pumping methane gas onto copper substrates heated to temperatures around 1,000 °C, and then transferring the graphene to another surface such as silicon. But some of the graphene sticks to the copper surface, and as the graphene and copper expand and contract at different rates, wrinkles form in the graphene sheets. Such wrinkles often present hurdles for charge carriers and lower the film’s conductivity. Other researchers have tried to reduce wrinkles using low growth temperatures or special copper substrates, but the wrinkles have proven difficult to eliminate entirely, according to Libo Gao, a physicist at Nanjing University.

Graphene enables researchers to visualize the flow of electrons

Researchers from Israel's Weizmann Institute and the UK's Manchester University have succeeded in imaging electrons' hydrodynamic flow pattern for the first time using a novel scanning probe technique. They have proven the longstanding scientific theory that electrons can behave like a viscous liquid as they travel through a conducting material, producing a spatial pattern that resembles water flowing through a pipe.

The results of this study could help developers of future electronic devices, especially those based on 2D materials like graphene in which electron hydrodynamics is important.

Graphenea launches highly flat monolayer graphene on copper thin film

Graphenea has announced the launch of a new product – highly flat monolayer graphene. The graphene is grown by CVD on copper thin film on a 2” sapphire substrate. With extremely low roughness that is less than 4 nm, this new product is targeted at applications in photonics, high-performance electronics, magnetic memory, and freestanding membranes.

Graphenea's new flat monolayer graphene on copper thin film image

The product aims to meet wafer-scale integration requirements to build uniform graphene devices in a fashion compatible with current industrial fabrication methods. The flat graphene product is ready to be transferred by electrochemical delamination or dry methods since the sapphire substrate is robust enough to withstand mechanical damage, preventing tearing and wrinkling of the thin Cu sheet. The total wafer thickness is 430 micrometers. Full product information can be found in Graphenea's online store.