http://phys.org/news/2015-09-delicately-band-gap-graphene-enables.htmlElectrons can move through graphene with almost no resistance, a property that gives graphene great potential for replacing silicon in next-generation, highly efficient electronic devices. But currently it's very difficult to control the electrons moving through graphene because graphene has no band gap, which means the electrons don't need to cross any energy barrier in order to conduct electricity. As a result, the electrons are always conducting, all the time, which means that this form of graphene can't be used to build transistors because it has no "off" state. In order to control the electron movement in graphene and enable "off" states in future graphene transistors, graphene needs a non-zero band gap—an energy barrier that can prevent electrons from conducting electricity when desired, making graphene a semiconductor instead of a full conductor.
In a new study, scientists have opened a band gap in graphene by carefully doping both sides of bilayer graphene in a way that avoids creating disorder in the graphene structure. Delicately opening up a band gap in graphene in this way enabled the researchers to fabricate a graphene-based memory transistor with the highest initial program/erase current ratio reported to date for a graphene transistor (34.5 compared to 4), along with the highest on/off ratio for a device of its kind (76.1 compared to 26), while maintaining graphene's naturally high electron mobility (3100 cm2/V·s). The researchers, led by Professor Young Hee Lee at Sungkyunkwan University and the Institute for Basic Science in Suwon, South Korea, have published their paper on the new method for opening up a band gap in graphene in a recent issue of ACS Nano.
