Related papers: Tunable Carrier Multiplication and Cooling in Grap…
One of the salient features of graphene is the very high carrier mobility that implies tremendous potential for use in electronic devices. Unfortunately, transport measurements find the expected high mobility only in freely suspended…
Hot, dense phases of Dirac fermions - predicted to resemble relativistic plasma - are uniquely accessible through photoexcitation of pristine, charge neutral graphene. We demonstrate a sensitive temperature probe of the photoexcited Dirac…
The dynamics of photocarriers in reduced graphene oxide thin films is studied by using ultrafast pump-probe spectroscopy. Time dependent differential transmissions are measured with sample temperatures ranging from 9 to 300 K. At each…
The optical properties of graphene are strongly affected by electron-electron (e-e) and electron-hole (e-h) interactions. Here we tune these many-body interactions through varying the density of free charge carriers. Measurements from the…
Graphene as a zero-bandgap semiconductor is an ideal model structure to study the carrier relaxation channels, which are inefficient in conventional semiconductors. In particular, it is of fundamental interest to address the question…
Hot carriers in a doped graphene under dc electric field is described taking into account the intraband energy relaxation due to acoustic phonon scattering and the interband generation-recombination transitions caused by thermal radiation.…
Graphene phonons are measured as a function of electron doping via the addition of potassium adatoms. In the low doping regime, the in-plane carbon G-peak hardens and narrows with increasing doping, analogous to the trend seen in graphene…
The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on doped graphene layers were studied by ab initio simulations. Electron doping was found to heighten the diffusion potential barrier, while hole doping lowers it.…
Graphene is an ideal material to study fundamental Coulomb- and phonon-induced carrier scattering processes. Its remarkable gapless and linear band structure opens up new carrier relaxation channels. In particular, Auger scattering bridging…
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…
We modulate the atomic structure of bilayer graphene by driving its lattice at resonance with the in-plane E1u lattice vibration at 6.3um. Using time- and angle-resolved photoemission spectroscopy (tr-ARPES) with extreme ultra-violet (XUV)…
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)…
The nonlinear response of electrons (holes) in doped graphene on ac pumping is considered theoretically for the frequency region above the energy relaxation rate but below the momentum and carrier-carrier scattering rates.…
Long lifetimes of hot carriers can lead to qualitatively new types of responses in materials. The magnitude and time scales for these responses reflect the mechanisms governing energy flows. We examine the microscopics of two processes…
Optical pump-terahertz probe differential transmission measurements of as-prepared single layer graphene (AG)(unintentionally hole doped with Fermi energy $E_F$ at $\sim$180 meV), nitrogen doping compensated graphene (NDG) with $E_F$…
Sulfur and nitrogen dual doped graphene have been extensively investigated in the field of oxygen reduction reaction, supercapacitors and batteries, but their magnetic and absorption performance have not been explored. Besides, the effects…
Three dimensional (3D) Dirac semimetals which can be seen as 3D analogues of graphene have attracted enormous interests in research recently. In order to apply these ultrahigh-mobility materials in future electronic/optoelectronic devices,…
In this work, we investigate the possibility of enhancing the thermoelectric power (Seebeck coefficient) in graphene devices by strain and doping engineering. While a local strain can result in the misalignment of Dirac cones of different…
The exceptional electronic properties of monoatomic thin graphene sheets triggered numerous original transport concepts, pushing quantum physics into the realm of device technology for electronics, optoelectronics and thermoelectrics. At…
Carrier multiplication is a many-particle process giving rise to the generation of multiple electron-hole pairs. This process holds the potential to increase the power conversion efficiency of photovoltaic devices. In graphene, carrier…