RESUMO
Fabrication of practical devices based on the transient metal dichalcogenides (TMDs) can be successively extended to various areas of the applications if the large area growth technology can be intentionally controlled and the characteristics of the layers can be easily predicted. In present work we presented the principles of the technology control based on the single key variable that can be directly related to the sequence of the technological processes. The atomically thin MoS2 layers were used as a model material and the layers were obtained by the CVD synthesis of the molybdenum precursor. Our thorough study demonstrated that the method allowed to deliberately choose the number of the MoS2 two-dimensional (2D)-layers between 1 and 10 by simply choosing the precursor deposition time. The optical properties of the layers were characterised by the optical transitions that corresponded to the known band structure of the MoS2 layers. Fused calibration diagram was proposed as the practical tool for the technology control and it was proved to be highly successive in relating the 2D-properties of the films with the initial stage of the fabrication technology. The method can be adapted to the wafer size TMDs growth on the diverse substrates.
RESUMO
The acousto-optic control of light polarization due to diffraction by leaky acoustic waves in ZX-LiNbO3 has been demonstrated. The randomly polarized light of 633 nm wavelength is converted by the anisotropic diffraction into two beams with mutually orthogonal polarizations, the relative intensities of which depend on the light incidence angle and acoustic frequency. Variation in acoustic frequency from 108 to 112 MHz rotates the polarization of the output optical beam by 90°. The acousto-optic control is accomplished entirely by electronic means and can be applied for implementation of fast polarization converters.