Researchers at the Surface and Interface Science Laboratory (RIKEN), Japan believe that the two-dimensional graphene structure can be used to make semiconductors. Graphene, a thin layer made of pure carbon, is a tightly packed layer of carbon atoms that has been bonded in a hexagonal honeycomb structure. The structure can be complicated by the formation of wrinkles from this allotrope carbon. The graphene can also interact with its substrate, which is the layer or substance it is placed on. This adds complexity.
In Nature Communications, the RIKEN researchers explained that graphene wrinkles can limit electrons in one direction. This creates a junction-like structure which shifts zero-gap from semiconductor to conductor back to zero. Schematic of a graphene Nanowrinkle. Image: www.riken.jp. They created wrinkles by manipulating the tip of the scanning tunneling microscope.
This opens up the possibility of creating graphene semiconductors without using chemical methods (with other elements added), but with a form called graphene engineering (manipulating carbon structure). Scientists discovered their method of creating graphene films by chemical vapor deposition, which is the best known and most reliable.
The temperature and speed at which graphene is formed on a nickel substrate were key factors in their discovery. Hyunseob, the first author of the paper, stated that they tried to form graphene from a nickel substrate. However, the temperature and cooling speed are crucial. Normal electron holes and electrons can flow through conductors with zero band gaps. It is possible for electrons to only pass through certain gaps when it’s a semiconductor.
The scan tunneling microscope images show graphene with nanowrinkles. According to the wrinkles, graphene may become a semiconductor. The researchers initially considered two options for the formation of the band gap.
1. A magnetic phenomenon could be caused by mechanical strain.
It was eliminated.
2. This was likely due to the confinement electrons within a single dimension by ‘quantum confinement.
Yousoo, the Surface and Interface Science Laboratory’s team leader, stated that “up until now, attempts to modify the electronic characteristics of graphene had primarily been made through chemical methods, but that has the disadvantage of causing degraded electronics due to chemical defects.” This will make it exciting to discover if there are new ways to use graphene. In fact, Oak Ridge National Laboratory scientists showed earlier this year that large-scale graphene can be made.
