In this Letter, we present nondegenerate ultrafast optical pump-probe studies of the carrier recombination dynamics in MoS2 monolayers. By tuning probe to wavelengths much longer than exciton line, make transmission sensitive total population photoexcited electrons and holes. Our measurement reveals two distinct time scales over which holes recombine; a fast scale that lasts ∼ 2 ps slow 100 ps. The temperature pump fluence dependence observed are consistent with defect-assisted as being...

We measure the optical-absorption spectra and optical conductivities of excitons trions in monolayers metal dichalcogenide MoS${}_{2}$ compare results with theoretical models. Our show that Wannier-Mott model for modifications to account small exciton radii large relative wave function spread momentum space, phase space blocking due Pauli exclusion doped materials, wave-vector-dependent dielectric constant gives agree well experiments. The measured are used obtain experimental estimates fall...

We present results on the radiative lifetimes of excitons and trions in a monolayer metal dichalcogenide ${\mathrm{MoS}}_{2}$. The small exciton radius large optical oscillator strength result 0.18--0.30 ps range for that have in-plane momenta couple to radiation. Average thermally distributed depend linearly temperature can be few picoseconds at temperatures more than nanosecond near room temperature. Localized exhibit same lifetime increases as localization length decreases. are hundreds...

We present results on photoexcited carrier lifetimes in few-layer transition metal dichalcogenide MoS2 using nondegenerate ultrafast optical pump-probe technique. Our show a sharp increase of the with number layers sample. Carrier from few tens picoseconds monolayer samples to more than nanosecond 10-layer samples. The inverse lifetime was found scale according probability carriers being at surface layers, as given by wavefunction layer samples, which can be treated quantum wells. were...

Using ultrafast optical pump-probe spectroscopy, we study the relaxation dynamics of hot phonons in few-layer and multi-layer graphene films grown by epitaxy on silicon carbide substrates chemical vapor deposition nickel substrates. In first few hundred femtoseconds after photoexcitation, carriers lose most their energy to generation which then present main bottleneck subsequent carrier cooling. Optical phonon cooling short time scales is found be independent growth technique, number layers,...

Abstract The strong light emission and absorption exhibited by single atomic layer transitional metal dichalcogenides in the visible to near-infrared wavelength range make them attractive for optoelectronic applications. In this work, using two-pulse photovoltage correlation technique, we show that monolayer molybdenum disulfide photodetector can have intrinsic response times as short 3 ps implying photodetection bandwidths wide 300 GHz. fast is a result of electron–hole exciton lifetimes...

Using optical-pump terahertz-probe spectroscopy, we study the relaxation dynamics of photoexcited carriers in graphene at different temperatures. We find that lower temperatures tail transients as measured by differential probe transmission becomes slower, extending beyond several hundred picoseconds below 50K. interpret observed resulting from cooling via phonon emission. The slow low is attributed to bulk electron and hole energy distributions moving close enough Dirac point such both...

The strong Coulomb interactions and the small exciton radii in two-dimensional metal dichalcogenides can result very fast capture of electrons holes excitons by mid-gap defects from Auger processes. In processes considered here, an is annihilated at a defect site with electron (or hole) hole electron) scattered to high energy. case excitons, probability finding near each other enhanced many folds compared free uncorrelated holes. Consequently, rate carrier scattering for be 100--1000 times...

Electron-hole generation and recombination rates for plasmon emission absorption in graphene are presented. The times of carriers due to found be the tens femtoseconds hundreds picoseconds range. depend sensitively on carrier energy, density, temperature, dispersion. Carriers near Dirac point have much longer lifetimes compared at higher energies. Plasmons a layer polar substrate hybridize with surface optical phonons this hybridization modifies We also present layers substrates.

We present results on the relaxation dynamics of photoexcited carriers in MoS2 using optical-pump terahertz-probe spectroscopy. Our measurements indicate that carrier recombination is accelerated at low temperatures where defect-assisted becomes more efficient.

Graphene has emerged as the semiconductor with highest reported mobility of carriers at room temperature making it suitable for terahertz applications. The plasmon frequencies graphene are also in range. Plasmons interact strongly electrons and holes emission absorption fastest mechanisms electron-hole recombination generation. Plasmon density states can be modified patterned nanoscale thereby enabling one to control well carrier dynamics. We present spectroscopy results relaxation dynamics...

We present results on the relaxation dynamics of photoexcited carriers in graphene using optical-pump terahertz-probe spectroscopy. Our measurements indicate that carrier cooling is extremely slow at low temperatures where electron-optical phonon becomes inefficient.

Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text H. Wang, J. Strait, F. Rana, C. Ruiz-Vargas, and Park, "Thermoelectric Vs. Photoelectric Response of Graphene-Metal Photodetectors," in CLEO:2011 - Laser Applications Photonic Applications, OSA Technical Digest (CD) (Optica Publishing Group, 2011), paper JThB31. Export BibTex Endnote (RIS) HTML Plain alert Save article

We present results from measurements of ultrafast thermal transport in Graphene. find that on picosecond time scales and 5-20 micron length hot carriers, instead the phonons, are dominant carriers energy. The is found to be diffusive with a diffusivity ~500 cm2/s.

Two-dimensional atomically thin materials, most notably graphene and transition metal dichalcogenides (TMDs), have generated tremendous interest among researchers. The high electron mobility strong light absorption exhibited by these materials make them attractive for opto-electronic applications. We will present our recent experimental theoretical work on the ultrafast dynamics of collective excitations, such as excitons, phonons, plasmons, in electronic photonic device study excitons 2D...