Graphene, a material consisting of carbon atoms arranged in a hexagonal lattice, has gained significant attention due to its unique electronic properties. One of the most intriguing aspects of graphene is its potential as a conducting material, but the precise mechanism by which it transitions from a valence band to an energy level called the conduction band is not fully understood.
(where onset of interband absorption happens in graphene)
One possible explanation for the onset of interband absorption in graphene is the presence of quantum spintronics effects. Graphene is a two-dimensional material, with electrons and holes moving simultaneously in different directions. This can result in strong electron-hole pairs, which can lead to significant changes in electrical conductivity.
The transition between the valence band and the conduction band occurs through a process called the photoinduced conduction (PIC). When light shines on graphene, it can cause the electrons and holes to become excited, and their movement can be facilitated by a local field created by the light.
The magnitude of this local field can vary depending on the intensity and frequency of the light. As the light intensity increases or the frequency decreases, the local field becomes stronger, which can result in a more significant change in the conduction band position.
In addition to the photoinduced conduction effect, there are other mechanisms that can contribute to the onset of interband absorption in graphene. For example, electron localization effects can occur when the electrons and holes in the graphene crystal lattice become strongly localized around specific sites. These localized sites can create additional electron-hole pairs, leading to an increase in the net conductance of the system.
Another mechanism that can contribute to interband absorption in graphene is the formation of impurities or defects in the graphene crystal lattice. Impurities can alter the charge distribution within the graphene structure, which can affect the density of states at the conduction band and the transitions between the valence band and the conduction band.
(where onset of interband absorption happens in graphene)
Overall, the onset of interband absorption in graphene is likely influenced by a combination of quantum spintronics effects, local field effects, and the formation of impurities or defects in the graphene crystal lattice. Further research is needed to better understand these mechanisms and their implications for the development of new applications for graphene-based materials.
