| dc.description.abstract | The in-plane acoustic phonon-related issues in graphene include the in-plane acoustic phonon
scatterings in the whole temperature range (from low- to high-temperature regime), the dopingdependent
Bloch-Grüneisen temperatures, and the effect of shortages of in-plane acoustic phonon
momenta to scatter off electrons at Bloch-Grüneisen temperatures. While the first and second
issues have been attracting a lot of theoretical and experimental researches during the last
decade, the third issue remains unexplored. It is worth mentioning that fully comprehending
these issues in graphene is not only important for fundamental understanding but also for designing
graphene-based devices such as optical detectors, bolometers, cooling pathways, and
supercollisions in graphene.
In this thesis, I systematically investigate the three issues in unprecedented details. Regarding
the first issue, the inelastic and semi-inelastic scattering rates at any finite temperature and
doping are derived rigorously, from which the high-temperature scattering rate is reproduced
and the low-temperature scattering rate is corrected. In addition, the ansatz scattering rate
manifests its asymptotic behavior to our scattering rates for the whole temperature range; especially,
the overestimation becomes greater in the low-temperature region. As a test bed, our
scattering rates well fit the available experimental data in the literature.
For the second issue, it turns out that the state-of-the-art definitions of the doping-dependent
Bloch-Grüneisen temperatures need to be revised. Their values should be about 2 ? 2.5 times
smaller. Moreover, the total doping-dependent Bloch-Grüneisen temperatures emerge. Using
our scattering rates to analyze the available experimental data in the literature, the experimentally
inferred values of the total doping-dependent Bloch-Grüneisen temperatures completely
agree with our theoretically predicted values. Additionally, critical mistakes and inconsistencies
in some theoretical and experimental works are also pointed out. Furthermore, our new
results question many theoretical researches of formulations relating to the doping-dependent
Bloch-Grüneisen temperatures in graphene.
Finally, the last but not the least, as far as I have known since the two works by F. Bloch in
1930 and E. Grüneisen in 1933, shortages of acoustic phonon momenta to scatter off electrons
at doping-dependent Bloch-Grüneisen temperatures are observed for the first time. As an application,
we have used our scattering rates to study transfer current in p-type graphene/MoS2
heterostructures under a wide range of applied gate voltage at 300 K without and with optical
pumping. | en_US |