相关论文: Influence of doping on non-equilibrium carrier dyn…
Chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of…
To minimize parasitic doping effects caused by uncontrolled material adsorption, graphene is often investigated under vacuum. Here we report an entirely unexpected phenomenon occurring in vacuum systems, namely strong n-doping of graphene…
We achieve fine tuning of graphene effective doping by applying ultrahigh pressures (> 10 GPa) using Atomic Force Microscopy (AFM) diamond tips. Specific areas in graphene flakes are irreversibly flattened against a SiO2 substrate. Our work…
A degenerate pump--probe technique is used to investigate the non equilibrium carrier dynamics in multi--layer graphene. Two distinctly different dynamics of the carrier relaxation are observed. A fast relaxation ($\sim 50$ fs) of the…
The equilibrium optical phonons of graphene are well characterized in terms of anharmonicity and electron-phonon interactions, however their non-equilibrium properties in the presence of hot charge carriers are still not fully explored.…
Bipolar carrier transport is often a limiting factor in the thermoelectric efficiency of narrow bandgap materials at high temperatures due to the reduction in the Seebeck coefficient and the introduction of an additional term to the thermal…
We perform a femtosecond-THz optical pump-probe spectroscopy to investigate the cooling dynamics of hot carriers in quasi-free standing bilayer epitaxial graphene. We observed longer decay time constants, in the range of 2.6 to 6.4 ps,…
A method for determining the type of charge carrier, electron or hole, which is transferred from metal contacts to graphene, is described. The Dirac point is found to shift toward more negative (positive) gate voltages for electron (hole)…
Chemical modification, such as intercalation or doping of novel materials is of great importance for exploratory material science and applications in various fields of physics and chemistry. In the present work, we report the systematic…
Density functional theory calculations suggest a pronounced hole electron doping asymmetry in a single layer graphene. It turns out that a single graphene sheet can sustain doping levels up to 0.1 holes or up to a remarkably large 1.9…
Density functional calculations are used to explain the charge transfer doping mechanism by which species physisorptively bonded to graphene can increase its free hole or electron density, without giving rise to defects, and thus maintain a…
Dirac Fermion, which is the low energy collective excitation near the Dirac cone in monolayer graphene, have gained great attention by low energy Terahertz probe. In the case of undoped graphene, it has been generally understood that the…
Using density-functional calculations, we show that electron or hole doped graphene can strongly change the mobility of adsorbed atoms H and O. Interestingly, charge doping affects the diffusion of H and O in the opposite way, namely,…
The ultrafast dynamics of excited carriers in graphene is closely linked to the Dirac spectrum and plays a central role for many electronic and optoelectronic applications. Harvesting energy from excited electron-hole pairs, for instance,…
Due to their unique dimensionality, the physical properties of two-dimensional materials are deeply impacted by their surroundings, calling for a thorough understanding and control of these effects. We investigated the influence of the…
Penta-graphene is a quasi-two-dimensional carbon allotrope consisting of a pentagonal lattice in which both sp2 and sp3-like carbons are present. Unlike graphene, penta-graphene exhibits a non-zero bandgap, which opens the possibility of…
Graphene is thought to be a promising materials for many applications. However, pristine graphene is not suitable for most electrochemical devices, where defect engineering is crucial for its performance. We demonstrate how boron doping of…
The role of doping in tailoring thermal transport in semiconductors is critical for efficient thermal management in electronic devices. While the effects of doping have been extensively studied to tune electrical properties, its impact on…
The influence of plasma etched sample edges on electrical transport and doping is studied. Through electrical transport measurements the overall doping and mobility are analyzed for mono- and bilayer graphene samples. As a result the edge…
We consider hot carrier inelastic scattering due to electron--electron interactions in graphene, as functions of carrier energy and density. We calculate the imaginary part of the zero-temperature quasiparticle self-energy for doped…