The effect of the experimental parameters on the growth of MoS₂ flakes

Abstract

The growth mechanism and optical performance of MoS2 crystals have been systemically studied by manipulating the growth parameters.

Multilayered Vertical Heterostructures Comprised of MoS2 and WS2 Nanosheets for Optoelectronics

“…The Raman spectra of the two samples in Figure S2d include two predominant vibration peaks located at constant positions, ∼381.8 and 401.8 cm –1 , ascribed to characteristic the E 1 2g (Γ) and A 1g (Γ) Raman modes for 1L MoS 2 . Moreover, the peak spacing of two such typical modes is estimated to be ∼20 cm –1 , analogous to that of a CVD-grown 1L MoS 2 , corroborating the single-layer feature of the two MoS 2 samples. In addition, Figure S2e provides the representative PL spectra of the two MoS 2 samples.…”

“…As the growth temperature continues to rise to 900 °C, large-scale triangular-like MoS 2 crystals with a longer average edge length of ∼82 μm can be obtained, and the light-purple color of the flakes is uniform, verifying the no fluctuation of the thickness across the triangle, while some larger flakes have a tiny dark region at the very center, ascribed to the thicker nucleation site. Significantly, the average edge length of the MoS 2 crystals obtained at 900 °C is obviously larger than that of the MoS 2 flakes grown at 875 °C, attributed to the fact that a higher growth temperature can generate a higher Mo atom concentration in the vapor and promote the growth rate of MoS 2 crystals . The detailed layer number and crystal quality of the MoS 2 samples obtained at 875 and 900 °C are further analyzed by employing Raman and PL spectroscopy, as depicted in Figure S2d,e.…”

“…Significantly, the average edge length of the MoS 2 crystals obtained at 900 °C is obviously larger than that of the MoS 2 flakes grown at 875 °C, attributed to the fact that a higher growth temperature can generate a higher Mo atom concentration in the vapor and promote the growth rate of MoS 2 crystals. 37 The detailed layer number and crystal quality of the MoS 2 samples obtained at 875 and 900 °C are further analyzed by employing Raman and PL spectroscopy, as depicted in Figure S2d,e. The Raman spectra of the two samples in Figure S2d include two predominant vibration peaks located at constant positions, ∼381.8 and 401.8 cm −1 , ascribed to characteristic the E 1 2g (Γ) and A 1g (Γ) Raman modes for 1L MoS 2 .…”

Single-Layer MoS2 Grown on Atomically Flat SrTiO3 Single Crystal for Enhanced Trionic Luminescence

“…Further examining the sample surface with AFM reveals a uniform thickness of ∼0.87 nm for the as-grown MoS 2 nanosheets, corresponding to the single layer height of MoS 2 . 45,46 Simultaneously, the step-terrace structure of the SrTiO 3 (111) substrate is clearly viewed, as shown in Figure 1c, manifesting a well-defined atomic structure of the sample surface. To further investigate the atomic details of the MoS 2 -SrTiO 3 (111) heterostructure, we performed the same synthetic strategy to grow MoS 2 on a Nb-doped SrTiO 3 (111) single crystal substrate (shorten as MoS 2 -Nb-SrTiO 3 (111)) and measured with scanning tunneling microscopy (STM).…”

“…Figure b shows a scanning electron microscopy (SEM) image of the as-prepared MoS 2 -SrTiO 3 (111) sample which witnesses many triangular-shaped MoS 2 nanosheets that spread for 500 nm to 2 μm and orient either parallelly or antiparallelly to one certain direction, indicative of a typical epitaxial growth of MoS 2 on the SrTiO 3 (111) substrate. Further examining the sample surface with AFM reveals a uniform thickness of ∼0.87 nm for the as-grown MoS 2 nanosheets, corresponding to the single layer height of MoS 2 . , Simultaneously, the step-terrace structure of the SrTiO 3 (111) substrate is clearly viewed, as shown in Figure c, manifesting a well-defined atomic structure of the sample surface. To further investigate the atomic details of the MoS 2 -SrTiO 3 (111) heterostructure, we performed the same synthetic strategy to grow MoS 2 on a Nb-doped SrTiO 3 (111) single crystal substrate (shorten as MoS 2 -Nb-SrTiO 3 (111)) and measured with scanning tunneling microscopy (STM).…”