Time:2023.04.25Browse:1
Graphene already exists in nature, but it is difficult to peel off a single layer structure. Graphene is stacked layer by layer to form graphite, with a thickness of 1 millimeter containing approximately 3 million layers of graphene. A pencil lightly scratches on paper, leaving traces that may be several or even just one layer of graphene.
The carrier mobility of graphene at room temperature is about 15000 cm2/(V · s), which is 10 times more than that of silicon materials, and more than twice that of indium antimonide (InSb), the material with the highest known carrier mobility. Under certain conditions, such as low temperature, the carrier mobility of graphene can even reach 250000 cm2/(V · s). Unlike many materials, the electron mobility of graphene is less affected by temperature changes. At any temperature between 50 and 500K, the electron mobility of single-layer graphene is about 15000 cm2/(V · s).
In addition, the half integer quantum Hall effect of electron carriers and hole carriers in graphene can be observed by changing the chemical potential through the action of electric field. Scientists have observed this quantum Hall effect of graphene at room temperature. The carriers in graphene follow a special quantum tunnel effect, and will not produce backscattering when they encounter impurities, This is the reason for the local super conductivity and high carrier mobility of graphene. The electrons and photons in graphene have no stationary mass, and their velocity is a constant independent of kinetic energy.
Graphene is a zero distance semiconductor because its conduction and valence band meet at the Dirac point. Brillouin at the edge of the momentum space at six positions of the Dirac point is divided into two groups of equivalent triplets. In contrast, the main points of traditional semiconductors are generally Γ, The momentum is zero.