Schottky diodes are the grand daddy of semiconductor devices. They are formed when a semiconductor material is combined with a metal and the junction between the two materials creates the Schottky diode. Despite being around since forever, it’s never been quite possible to make them into an ideal diode in which when a voltage is applied it acts as conductor and when the voltage is reversed it serves as a insulator.
Now researchers at the Ulsan National Institute of Science and Technology (UNIST) in Korea have been able to produce the ideal version of the Schottky diode by inserting a graphene layer between the semiconductor and the metal, and in the process have eliminated 50 years of head scratching over this issue.
In research described in the journal Nano Letters, the UNIST researchers discovered that graphene serves to prevent the intermixing of atoms that occurs when the semiconductor and metal are touching each other directly.
“The space between the carbon atoms that make up the graphene layer has a high quantum mechanical electron density and therefore no atoms can pass through it,” said Kibog Park, a professor at UNIST and co-author of the paper, in a press release. “Therefore, by inserting the graphene layer between metal and semiconductor, it is possible to overcome the inevitable atomic diffusion problem.”
While the research solved this problem, it also confirmed a prediction that it didn’t matter what kind of metal was used to form the Schottky junction; the performance does not change significantly.
The applications for Schottky diodes are pretty broad, but the main use is that of a rectifier, which converts alternating current (AC) to direct current (DC). But so many electronic devices use these diodes that this research is expected to resolve what has been a long-standing issue within the electronic industry.