Temperature dependence of band gap in MoSe2 grown by molecular beam epitaxy

Choi, Byoung Ki; Kim, Minu; Jung, Kwang-Hwan; Kim, Jwasoon; Yu, Kyu-Sang; Chang, Young Jun

doi:10.1186/s11671-017-2266-7

Cited by 43 publications

(26 citation statements)

References 50 publications

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“…Figure 2 compares our results for a monolayer MoSe 2 domain at room temperature with previously reported data 13 , 14 , 33 . Structureless regions at energies less than 1 eV and more than 5 eV are deleted for clarity.…”

Section: Resultssupporting

confidence: 67%

“… Imaginary parts of dielectric spectra of monolayer MoSe 2 at room temperature compared to data previously reported in refs 13 , 14 , 33 . …”

Section: Resultsmentioning

confidence: 78%

“…The noisy feature at 1.24 eV seems to be an artifact caused by change of detectors, as explained in Methods below.

Figure 2 Imaginary parts of dielectric spectra of monolayer MoSe 2 at room temperature compared to data previously reported in refs 13 , 14 , 33 . …”

Section: Resultsmentioning

confidence: 86%

“…Spectroscopic ellipsometry (SE) is a precise and highly sensitive method for obtaining dielectric function data 12 . Several workers have reported dielectric functions of monolayer MoSe 2 using SE at room or high temperature, but these spectra are broad and transition peaks difficult to resolve 13 , 14 . To reduce thermal broadening, enhance weak features, and improve resolution, data must be obtained at cryogenic temperatures 15 – 17 .…”

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of the Dielectric Function of Monolayer MoSe2

Park

Kim

Ullah

et al. 2018

Sci Rep

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The dielectric function of monolayer molybdenum diselenide (MoSe2) is obtained and analyzed at temperatures from 31 to 300 K and at energies from 0.74 to 6.42 eV. The sample is a large-area, partially discontinuous monolayer (submonolayer) film of MoSe2 grown on a sapphire substrate by selenization of pulsed laser deposited MoO3 film. Morphological and optical characterizations verified the excellent quality of the film. The MoSe2 data were analyzed using the effective medium approximation, which treats the film and bare substrate regions as a single layer. Second derivatives of ε with respect to energy were numerically calculated and analyzed with standard lineshapes to extract accurate critical-point (CP) energies. We find only 6 CPs for monolayer MoSe2 at room temperature. At cryogenic temperatures 6 additional structures are resolved. The separations in the B- and C-excitonic peaks are also observed. All structures blue-shift and sharpen with decreasing temperature as a result of the reducing lattice constant and electron-phonon interactions. The temperature dependences of the CP energies were determined by fitting the data to the phenomenological expression that contains the Bose-Einstein statistical factor and the temperature coefficient.

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Section: Resultssupporting

confidence: 67%

“… Imaginary parts of dielectric spectra of monolayer MoSe 2 at room temperature compared to data previously reported in refs 13 , 14 , 33 . …”

Section: Resultsmentioning

confidence: 78%

“…The noisy feature at 1.24 eV seems to be an artifact caused by change of detectors, as explained in Methods below.

Figure 2 Imaginary parts of dielectric spectra of monolayer MoSe 2 at room temperature compared to data previously reported in refs 13 , 14 , 33 . …”

Section: Resultsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of the Dielectric Function of Monolayer MoSe2

Park

Kim

Ullah

et al. 2018

Sci Rep

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“…The error bars in the fit for temperature-dependent optical band gap are approximately 0.5%. Notably, in monolayer MoSe 2 , a previous ellipsometric study determined only the linear temperature dependence of the optical band gap for 300-800 K 22 . Figure 5 presents the absorption spectra for the higher photon energy regions (> 2.5 eV) of monolayer MoS 2 , MoSe 2 , WS 2 , and WSe 2 , which have a considerably higher intensity than those for the A and B exciton peaks.…”

Section: Resultsmentioning

confidence: 99%

Temperature-dependent optical constants of monolayer $${\text {MoS}}_2$$, $${\text {MoSe}}_2$$, $${\text {WS}}_2$$, and $${\text {WSe}}_2$$: spectroscopic ellipsometry and first-principles calculations

Liu

Yang

Chen

et al. 2020

Sci Rep

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The temperature-dependent ($$T = 4.5 \, \hbox {-} \, 500 \, \hbox {K}$$ T = 4.5 - 500 K ) optical constants of monolayer $${\text {MoS}}_2$$ MoS 2 , $${\text {MoSe}}_2$$ MoSe 2 , $${\text {WS}}_2$$ WS 2 , and $${\text {WSe}}_2$$ WSe 2 were investigated through spectroscopic ellipsometry over the spectral range of 0.73–6.42 eV. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 800 nm and approached a constant value of 3.5–4.0 in the near-infrared frequency range. With a decrease in temperature, the refractive indices decreased monotonically in the near-infrared region due to the temperature-dependent optical band gap. The thermo-optic coefficients at room temperature had values from $$6.1 \times 10^{-5}$$ 6.1 × 10 - 5 to $$2.6 \times 10^{-4} \, \hbox {K}^{-1}$$ 2.6 × 10 - 4 K - 1 for monolayer transition metal dichalcogenides at a wavelength of 1200 nm below the optical band gap. The optical band gap increased with a decrease in temperature due to the suppression of electron–phonon interactions. On the basis of first-principles calculations, the observed optical excitations at 4.5 K were appropriately assigned. These results provide basic information for the technological development of monolayer transition metal dichalcogenides-based photonic devices at various temperatures.

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Optical Harmonic Generation in 2D Materials

Khan

Zhang

Ishfaq

et al. 2021

Adv Funct Materials

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2D materials are emerging as ideal candidates for fundamental investigations and new technologies due to their unique optoelectronic properties. Giant nonlinear susceptibility and perfect phase matching in 2D materials lead to extraordinary nonlinear light matter interactions, thus enabling several potential applications and fundamental scientific discoveries in nonlinear optics. For instance, second harmonic generation in 2D materials play an important role in optical devices such as, lasers, tunable waveguides, electro‐optic modulators, and switches. This review will discuss optical harmonic generation (OHG) processes, various characterization modes, and tuning techniques in 2D materials. The future prospectives for OHG in 2D materials is discussed. The extremely promising attributes of combining nonlinear optics and 2D materials is becoming a highly important multidisciplinary field.

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Temperature dependence of band gap in MoSe2 grown by molecular beam epitaxy

Cited by 43 publications

References 50 publications

Temperature Dependence of the Dielectric Function of Monolayer MoSe2

Temperature Dependence of the Dielectric Function of Monolayer MoSe2

Temperature-dependent optical constants of monolayer $${\text {MoS}}_2$$, $${\text {MoSe}}_2$$, $${\text {WS}}_2$$, and $${\text {WSe}}_2$$: spectroscopic ellipsometry and first-principles calculations

Optical Harmonic Generation in 2D Materials

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