Fermi liquid theory sheds light on hot electron-hole liquid in 1L−MoS2

Enhanced Emission from Defect Levels in Multilayer MoS2

“…Two possible mechanisms have been previously associated with abrupt changes in PL intensity: electron-hole liquid formation [28][29][30][31][32][33] and a thermally driven electronic structure transition. [34] The possibility of electron-hole liquid formation can be ruled out since it requires large exciton binding energies that are only present in monolayer dichalcogenides (see Figure S10 in the Supporting Information for a more detailed discussion).…”

“…Similar defect emission behaviors were observed when the sample temperature is increased. Such an abrupt PL intensity increase under high laser fluence or high temperatures is usually signatures of either electron–hole liquid formation [ 28–33 ] or a thermally driven electronic structure transition. [ 34 ] We rule out the former option and attribute the abrupt PL intensity increase to a thermally driven crossover from indirect exciton emission to stimulated emission from a defect level.…”

“…Similar defect emission behaviors were observed when the sample temperature is increased. Such an abrupt PL intensity increase under high laser fluence or high temperatures is usually signatures of either electronhole liquid formation [28][29][30][31][32][33] or a thermally driven electronic structure transition. [34] We rule out the former option and Realizing stimulated emission from defects in 2D-layered semiconductors has the potential to enhance the sensitivity of characterizing their defects.…”

Ultrafast hot electron–hole plasma photoluminescence in two-dimensional semiconductors

“…It is known that the high carrier density can result in a renormalization of the band structure due to carrier–carrier interactions. 40 Moreover, as shown by Wilmington et al , 20 high excitation densities can also lead to sample strain in these TMDs. Besides, it has been reported by Desai et al 41 that strain in multilayer WSe 2 induces an indirect to direct band gap transition.…”

“…8–10 As 2D TMDs show suppressed dielectric screening, the formation of tightly bound excitons at temperatures well above room temperature was observed due to their large binding energies of hundreds of meV. 11–13 Therefore, these materials have shown to be an ideal platform to exploit and investigate many body phenomena, including the exciton Mott transition as reported by theoretical and experimental works in several TMD samples such as MoS 2 , 14–20 WS 2 , 21,14 WSe 2 , 14,22 and MoTe 2 , 23 and also TMD heterostructures. 24–27 However, there are still few studies on the light emission properties like photoluminescence (PL) in TMDs showing their interesting optical and electronic responses at high carrier densities above the Mott critical value.…”