UNIST to Engineer Dream Diodes with a Graphene Interlayer
February 1, 2017 | UNISTEstimated reading time: 2 minutes
A team of researchers, affiliated with UNIST has created a new technique that greatly enhances the performance of Schottky Diodes (metal-semiconductor junction) used in electronic devices. Their research findings have attracted considerable attention within the scientific community by solving the contact resistance problem of metal-semiconductor, which had remained unsolved for almost 50 years.
As described in the January issue of Nano Letters, the researchers have created a new type of diode with a graphene insertion layer sandwiched between metal and semiconductor. This new technique blows all previous attemps out the water, as it is expected to significantly contribute to the semiconductor industry’s growth.
The Schottky diode is one of the oldest and most representative semiconductor devices, formed by the junction of a semiconductor with a metal. However, due to the atomic intermixing along the interface between two materials, it has been impossible to produce an ideal diode. (An ideal diode acts like a perfect conductor when voltage is applied forward biased and like a perfect insulator when voltage is applied reverse biased.)
graphene interlayer 2The schematic view of internal photoemission (IPE) measurements on metal/n-Si(001) junctions with Ni, Pt, and Ti electrodes for with and without a graphene insertion layer.
Professor Kibog Park of Natural Science solved this problem by inserting a graphene layer at the metal-semiconductor interface. In the study, the research team demonstrated that this graphene layer, consisting of a single layer of carbon atoms can not only suppress the material intermixing substantially, but also matches well with the theoretical prediction.
“The sheets of graphene in graphite have a space between each sheet that shows a high electron density of quantum mechanics in that no atoms can pass through,” says Professor Park. “Therefore, with this single-layer graphene sandwiched between metal and semiconductor, it is possible to overcome the inevitable atomic diffusion problem.”
The study also has the physiological meaning of confirming the theoretical prediction that “In the case of silicon semiconductors, the electrical properties of the junction surfaces hardly change regardless of the type of metal they use,” according to Hoon Hahn Yoon (Combined M.S./Ph.D. student of Natural Science), the first author of the study.
The internal photoemission method was used to measure the electronic energy barrier of the newly-fabricated metal/graphene/n-Si(001) junction diodes. The Internal Photoemission (IPE) Measurement System in the image shown above has contributed greatly to these experiments. This system has been developed by four UNIST graduate students (Hoon Han Yoon, Sungchul Jung, Gahyun Choi, and Junhyung Kim), which was carried out as part of an undergraduate research project in 2012 and was supported by the Korea Foundation for the Advancement of Science and Creativity (KOFAC).
“Students have teamed up and carried out all the necessary steps for the research since they were undergraduates,” Professor Park says. “Therefore, this research is a perfect example of time, persistence, and patience paying off.”
This study has been jointly conducted by Professor Hu Young Jeong of the UNIST Central Research Facilities (UCRF), Professor Kwanpyo Kim of Natural Science, Professor Soon-Yong Kwon of Materials Science and Engineering, and Professor Yong Soo Kim of Ulsan University. It has been also supported by the National Research Foundation of Korea, Nuclear Research Basis Expansion Project, as well as the Global Ph.D Fellowship (GPF).
Suggested Items
epoxySet Introduces EO-20E – Versatile, Electrically Conductive Epoxy
04/29/2024 | epoxySetepoxySet produces EPOXIOHM EO-20E an industry established, reliable electrically conductive epoxy designed for solder replacement, chip bonding and other intricate electronic and optoelectronic assemblies. This creamy paste has a an easy to use 1:1 mix ratio with a 48 hour work time.
The Right Approach: I Hear the Train A Comin'
04/25/2024 | Steve Williams -- Column: The Right ApproachTraining is often an afterthought in many organizations, and the longer a company has been in business, the more this seems to apply. Over the past couple of decades, it has been amazing to observe that the biggest offenders of this are the companies that overuse the sound bite, “Our most important assets are our people.” When you dig into the process and peel back the onion, their commitment to training is not commensurate with that statement.
Big Win for Defense Production Act Budget Allocation in FY24 Budget
04/23/2024 | I-Connect007 Editorial TeamOne year ago, President Biden issued a determination that chips and packaging are critical for national security. Since that time, much work has been done to continue the conversation in Washington, elevating the importance of the entire chips value chain, and including printed circuit boards and substrates, without which chips cannot operate.
IDTechEx Examines the Opportunities for Wearables in Digital Health
04/19/2024 | IDTechExIDTechEx’s report, “Digital Health and Artificial Intelligence 2024-2034: Trends, Opportunities, and Outlook”, covers this ongoing trend in the consumer health wearables market and includes analysis of the opportunities and roadmap for biometric monitoring.
NCAB Appoints Tim Benjamin as New CFO
04/15/2024 | NCAB GroupNCAB Group has appointed Tim Benjamin as its new CFO. Tim has a long and broad experience of managerial business finance roles, including M&A and IT.