Electronic structure of graphene nano-ribbons
Author
Şen, Hüseyin Şener
Advisor
Gülseren, Oğuz
Date
2008Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
95
views
views
48
downloads
downloads
Abstract
Graphite is a known material to human kind for centuries as the lead of a pencil.
Graphene as a two dimensional material, is the single layer of graphite. Many
theoretical works have been done about it so far, however, it newer took attention
as it takes nowadays. In 2004, Novoselov et al. was able to produce graphene
in 2D. Now that, making experiments on graphene is possible scientists have
to renew their theoretical knowledge about systems in two dimension because
graphene, due to its electronic structure, is able to prove the ideas in quantum
relativistic phenomena. Indeed, recent theoretical studies were able to show that,
electrons and holes behave as if they are massless fermions moving at a speed
about 106m/s (c/300, c being speed of light) due to the linear electronic band
dispersion near K points in the brillouin zone which was observed experimentally
as well.
Having zero band gap, graphene cannot be used directly in applications as
a semiconductor. Graphene Nano-Ribbons (GNRs) are finite sized graphenes.
They can have band gaps differing from graphene, so they are one of the new candidates
for band gap engineering applications such as field effect transistors. This
work presents theoretical calculation of the band structures of Graphene NanoRibbons
in both one (infinite in one dimension) and zero dimensions (finite in both
dimensions) with the help of tight binding method. The calculations were made
for Zigzag, Armchair and Chiral Graphene Nano-Ribbons (ZGNR,AGNR,CGNR)
in both 1D and 0D. Graphene nano-ribbons with zero band gap (ZGNR and
AGNR) are observed in the calculations as well as the ribbons with finite band
gaps (AGNR and CGNR) which increase with the decrease in the size of the
ribbon making them much more suitable and strong candidate to replace silicon
as a semiconductor.
Keywords
Graphenechiral vector
chiral angle
quantum confinement
0D
1D
CGNR
ZGNR
AGNR
band gap
hydrogen saturation of dangling bonds
electronic structure
tight binding
nano-ribbon