Photo-induced doping effect and dynamic process in monolayer MoSe₂

Abstract

Dynamic processes of electron transfer by optical doping in monolayer MoSe2 at 6 K are investigated via measuring time resolved photoluminescence (PL) traces under different excitation powers. Time-dependent electron transfer process can be analyzed by a power-law distribution of t −α with α = 0.1–0.24, depending on the laser excitation power. The average electron transfer time of approximately 27.65 s is obtained in the excitation power range of 0.5 to 100 μW. As the temperature increases from 20 to 44 K, the energy difference between the neutral and charged excitons is observed to decrease.

Interfacial charge and energy transfer in van der Waals heterojunctions

“…Such anomalous enhancement in mobility is attributed to the screening of defect scattering centers by injecting electrons. [129][130][131] Meanwhile, the carrier lifetime is enhanced with the formation of trions, which induces a high optical gain, thus enhancing the photodetector responsivity by ~5 times. Similarly, the responsivity of Cs 2 CO 3 decorated WSe 2 FET dramatically enhances by almost three orders of magnitudes.…”

“…Lin et al used Cs 2 CO 3 , a strong n ‐dopant, to functionalize the MoS 2 field‐effect transistor (FET), leading to the enhanced electron concentration and mobility. Such anomalous enhancement in mobility is attributed to the screening of defect scattering centers by injecting electrons 129–131 . Meanwhile, the carrier lifetime is enhanced with the formation of trions, which induces a high optical gain, thus enhancing the photodetector responsivity by ~5 times.…”

Review of Raman spectroscopy of two-dimensional magnetic van der Waals materials*

“…As a convenient and non-destructive tool with high spatial and spectral resolution, Raman spectroscopy has been widely used to characterize 2D materials. [49][50][51][52][53][54][55][56] The prominent features of Raman peaks, including frequency, full width at half maximum (FWHM), intensity, and line shape, contain useful information to investigate the fundamental physical properties of 2D materials, such as phonon frequency, the number of layers, stacking orders, electron-phonon coupling, charge density wave (CDW), phase transition, et al [57][58][59][60] The quantum picture of the inelastic Raman scattering process can be understood as shown in Fig. 2(a).…”

Biexciton and Singlet Trion Upconvert Exciton Photoluminescence in a MoSe2 Monolayer Supported by Acoustic and Optical K-Valley Phonons

“…The power-dependent evolution of the X PL intensity upconverted from T S is described by α Td S = 1.66, which reflects the power-dependent slope of the trion regular PL intensity. 21 Finally, we elucidate the polarization properties of the exciton PL upconverted from the negative trion and neutral biexciton states, yielding additional details on the UPC mechanisms, which are discussed in the following section. In Figure 4e the UPC PLE spectra are demonstrated for linearly polarized excitation and unpolarized detection, while in Figure 4f,g the incident light and the emission are cocircularly and cross-circularly polarized, respectively.…”

“…The practically quadratic power dependence (α XX 0 = 2.08) of I X,UPC , for E exc – E X = −18 meV, characterizes a process in which a biexciton is involved. The power-dependent evolution of the X PL intensity upconverted from T S is described by α T S = 1.66, which reflects the power-dependent slope of the trion regular PL intensity …”