Local photodoping in monolayer MoS₂

Abstract

Inducing electrostatic doping in 2D materials by laser exposure (photodoping effect) is an exciting route to tune optoelectronic phenomena. However, there is a lack of investigation concerning in what respect the action of photodoping in optoelectronic devices is local. Here, we employ scanning photocurrent microscopy (SPCM) techniques to investigate how a permanent photodoping modulates the photocurrent generation in MoS 2 transistors locally. We claim that the photodoping fills the electronic states in MoS 2 conduction band, preventing the photon-absorption and the photocurrent generation by the MoS 2 sheet. Moreover, by comparing the persistent photocurrent (PPC) generation of MoS 2 on top of different substrates, we elucidate that the interface between the material used for the gate and the insulator (gate-insulator interface)is essential for the photodoping generation. Our work gives a step forward to the understanding of the photodoping effect in MoS 2 transistors and the implementation of such an effect in integrated devices.

Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS2

“…Apart from the aforementioned analysis of the magneticfield dependence of transition energies, the applied magnetic field may also affect the emission intensities of the σ ± components. [54][55][56][57] As can be seen in Fig. 4(a), both σ ± components of the X 0 line are characterized by almost the same intensity in magnetic fields, which is characteristic for this complex in darkish MLs.…”

“…Recently, it has been demonstrated that the laser excitation may induce free electron concentration in MoS 2 MLs ranging up to several times 10 12 cm −2 . 56 Due to the small CB spin-orbit splitting and the photo-doping processes, we assumed that the Fermi level is high enough to provide free electrons on the higher energy CB subband allowing the formation of the intervalley triplet state of the negative trion.…”

Spatiotemporally Controlled Access to Photoluminescence Dark State of 2D Monolayer Semiconductor by FRAP Microscopy

“…Relatively non-blinking emission (i.e., the random PL intensity switching of a single emitter between "ON" and "OFF" state) in most 2D 1L-TMDs, [17,52] also endows it a stable PL background for monitoring the dynamics of photoexcited carriers upon an external carrier injection, such as photodoping. [53,54] Herein, we developed a two-laser beam technology to on-demand access to the PL dark state of 2D 1L-TMDs in a temporally-and spatially-controlled manner. This was based on the increased EEA effect upon instantaneous injection of abundant excitons via spatiotemporally-controlled high-power pump beam stimulation (photodoping).…”

“…Relatively non‐blinking emission (i.e., the random PL intensity switching of a single emitter between “ON” and “OFF” state) in most 2D 1L‐TMDs, [ 17,52 ] also endows it a stable PL background for monitoring the dynamics of photoexcited carriers upon an external carrier injection, such as photodoping. [ 53,54 ]…”

Anomalous Light-Induced Charging in MoS2 Monolayers with Cracks

“…Transition metal dichalcogenides (TMDs), as atomically thin semiconductors with near-infrared and visible range band gap energies, have been increasingly studied for optoelectronic device applications. − Integration of two-dimensional (2D) TMDs on three-dimensional (3D) nanostructures leads to interesting physical phenomena including enhanced optical absorption, plasmon-exciton coupling, strain-mediated exciton funneling, and interfacial charge transfer . Proof-of-concept experiments can be attempted using exfoliated TMD flakes, which have random shapes and sizes.…”