|
Descripción
|
|
|---|---|
| The experimental research of the last years on the properties of a single graphite layer dubbed graphene suggests that one may achieve the basis for new nanodevices. There are several experiments showing nowadays carrier mobility with values ~105cm2V-1s-1 or carrier concentrations below ~1010 cm-2 in graphene on substrates, grown on SiC or suspended. How are those values in comparison with those in the graphene layers inside graphite? Though graphite was studied systematically in the last ~70 years and scientists flooded the literature with reports on different kinds of electronic measurements, there was actually no real knowledge on the internal structure of the measured samples as well as the extraordinary sensitivity of the graphite structure to defects and their influence on transport. Recently done transport measurements in bulk as well as in mesoscopic, oriented thin graphite samples with micro-constrictions and multielectrodes indicate a mobility per graphene layer up to 100 times larger (carrier mean free path at 300K in the micrometer range) and carrier concentrations at least ~10 times smaller than the lowest measured in graphene. Furthermore, low-energy TEM characterization of graphite sub-mesoscopic structures as well as proton irradiation experiments on mesoscopic graphite samples provide evidence for the relationship between defects and measured carrier concentration. This new knowledge casts strong doubts on the relevance of the electronic band-structure and its tight binding parameters obtained in the past based on erroneous assumptions on the intrinsic properties of ideal graphite. In my talk I will shortly review and discuss old and new experimental evidence and argue that nowadays graphite appears to be a narrow gap semiconducting and multi-layer system with nearly decoupled two-dimensional graphene planes of much better quality than single isolated layers. | |
|
Internacional
|
No |
|
Nombre congreso
|
Cursos y Seminarios del ISOM |
|
Entidad organizadora
|
ISOM-ETSIT |
|
Nacionalidad Entidad
|
Sin nacionalidad |
|
Lugar/Ciudad de impartición
|
Madrid, España |
|
Fecha inicio
|
29/02/2012 |
|
Fecha fin
|
29/02/2012 |