Optically Discriminating Carrier-Induced Quasiparticle Band Gap and Exciton Energy Renormalization in MonolayerMoS2

Abstract

Optoelectronic excitations in monolayer MoS2 manifest from a hierarchy of electrically tunable, Coulombic free-carrier and excitonic many-body phenomena.Investigating the fundamental interactions underpinning these phenomenacritical to both many-body physics exploration and device applications -presents challenges, however, due to a complex balance of competing optoelectronic effects and interdependent properties. Here, optical detection of bound-and freecarrier photoexcitations is used to directly quantify carrier-induced changes of the quasiparticle band gap and exciton binding energies. The results explicitly disentangle the competing effects and highlight longstanding theoretical predictions of large carrier-induced band gap and exciton renormalization in 2D semiconductors. 2/20

Dielectric-dependent hybrid functionals for heterogeneous materials

“…[95], was neglected in our calculations. Therefore, we conclude that our quasiparticle gap is in reasonable agreement with the experimental value of 2.78(2) eV [96].…”

Many-body effects in doped WS2 monolayer quantum disks at room temperature

“…Due to the reduced dielectric screening and relatively heavy particle band masses, few-layered transition-metal dichalcogenide (TMDs) form tightly bound electron-hole pairs (excitons) with binding energies up to hundreds of meV, which is much larger than that in conventional bulk semiconductors. [1][2][3] The strongly bound excitons produce a variety of interesting multiparticle excitations such as charged excitons (trions), biexcitons, and exciton-trion complexes. [3][4][5] Because of efficient Coulomb interactions, few-layered TMDs are strongly interacting systems even in high carrier densities, thus, they provide an ideal vehicle to study fundamental many-body physics, such as band-gap renormalization and the Mott transition.…”

“…[3][4][5] Because of efficient Coulomb interactions, few-layered TMDs are strongly interacting systems even in high carrier densities, thus, they provide an ideal vehicle to study fundamental many-body physics, such as band-gap renormalization and the Mott transition. 2,[6][7][8] Carrier doping allows us to modulate the band structure of TMDs and manipulate their properties. By increasing the doping in few-layered TMDs, carriers can occupy the phase space of the conduction (valence) band at the K/K' points leading to the Pauli blocking effect, as originated from the Pauli exclusive principle.…”

“…6 A band-gap renormalization of over 150 meV and an exciton binding energy as large as 790 meV have also been demonstrated in monolayer molybdenum disulfide (MoS 2 ) through photoluminescence excitation (PLE). 2 With intense optical pulses, a Mott transition from excitons to free carriers has been observed accompanied by a huge band-gap renormalization. 7 To date, most of the experiments involving the many-body effects in TMDs have been performed at cryogenic temperature (50-80 K).…”

Phonon-assisted processes in the ultraviolet-transient optical response of graphene

“…Electronic properties of such systems are shown to be highly sensitive to external perturbation that introduces excess electron or hole concentrations. For instance, electrostatic and chemical doping techniques were successfully utilized in order to tune optical absorption as well as plasmon and exciton energies in graphene-based materials [3][4][5][6][7][8][9], transitions metal dichalcogenides [10][11][12][13][14][15][16], and corresponding van-der-Waals heterostructures [17,18].…”