New Method of Characterizing Graphene
May 30, 2017 | University of BaselEstimated reading time: 2 minutes
Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.
The layer of graphene (black honeycomb structure) encapsulated in boron nitride (blue) is placed on a superconductor (gray) and coupled with a microwave resonator. By comparing microwave signals (RF), the resistance and quantum capacitance of the embedded graphene can be determined. (Image: University of Basel, Department of Physics/Swiss Nanoscience Institute)
Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better conductor of electricity than copper. Since graphene was first isolated in 2004, scientists across the world have been researching its properties and the possible applications for the ultrathin material. Other two-dimensional materials with similarly promising fields of application also exist; however, little research has been carried out into their electronic structures.
No need for electrical contacts
Electrical contacts are usually used to characterize the electronic properties of graphene and other two-dimensional materials. However, these can significantly alter the materials’ properties. Professor Christian Schönenberger’s team from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics has now developed a new method of investigating these properties without applying contacts.
To do this, the scientists embedded graphene in the isolator boron nitride, placed it on a superconductor and coupled it with a microwave resonator. Both the electrical resistance and the quantum capacitance of the graphene affect the quality factor and resonance frequency of the resonator. Although these signals are very weak, they can be captured using superconducting resonators.
By comparing the microwave characteristics of resonators with and without encapsulated graphene, the scientists can determine both the electrical resistance and quantum capacitance. “These parameters are important in the determination of graphene’s exact properties and in the identification of limiting factors for its application,” explains Simon Zihlmann, a PhD student in Schönenberger’s group.
Also suitable for other two-dimensional materials
The boron nitride-encapsulated graphene served as a prototype material during the method’s development. Graphene integrated into other materials can be investigated in the same way. In addition, other two-dimensional materials can also be characterized without the use of electrical contacts; for example, the semiconductor molybdenum disulfide, which has applications in solar cells and optics.
Suggested Items
Elephantech: For a Greener Tomorrow
04/16/2025 | Marcy LaRont, PCB007 MagazineNobuhiko Okamoto is the global sales and marketing manager for Elephantech Inc., a Japanese startup with a vision to make electronics more sustainable. The company is developing a metal inkjet technology that can print directly on the substrate and then give it a copper thickness by plating. In this interview, he discusses this novel technology's environmental advantages, as well as its potential benefits for the PCB manufacturing and semiconductor packaging segments.
Trouble in Your Tank: Organic Addition Agents in Electrolytic Copper Plating
04/15/2025 | Michael Carano -- Column: Trouble in Your TankThere are numerous factors at play in the science of electroplating or, as most often called, electrolytic plating. One critical element is the use of organic addition agents and their role in copper plating. The function and use of these chemical compounds will be explored in more detail.
IDTechEx Highlights Recyclable Materials for PCBs
04/10/2025 | IDTechExConventional printed circuit board (PCB) manufacturing is wasteful, harmful to the environment and energy intensive. This can be mitigated by the implementation of new recyclable materials and technologies, which have the potential to revolutionize electronics manufacturing.
Connect the Dots: Stop Killing Your Yield—The Hidden Cost of Design Oversights
04/03/2025 | Matt Stevenson -- Column: Connect the DotsI’ve been in this industry long enough to recognize red flags in PCB designs. When designers send over PCBs that look great on the computer screen but have hidden flaws, it can lead to manufacturing problems. I have seen this happen too often: manufacturing delays, yield losses, and designers asking, “Why didn’t anyone tell me sooner?” Here’s the thing: Minor design improvements can greatly impact manufacturing yield, and design oversights can lead to expensive bottlenecks. Here’s how to find the hidden flaws in a design and avoid disaster.
Real Time with... IPC APEX EXPO 2025: Tariffs and Supply Chains in U.S. Electronics Manufacturing
04/01/2025 | Real Time with...IPC APEX EXPOChris Mitchell, VP of Global Government Relations for IPC, discusses IPC's concerns about tariffs on copper and their impact on U.S. electronics manufacturing. He emphasizes the complexity of supply chains and the need for policymakers to understand their effects.