Synthesis of WS2 crystals by the chemical vapor deposition (CVD) method on a SiO2 substrate

The synthesis and characterization of WS2 single crystals grown by chemical vapor deposition (CVD) method thru sulfurization of tungsten oxide thin layer on quartz substrate was studied. Synthesis of WS2 was carried out at 800-1000 °C in CVD system. The sulphur vapor is transported by argon gas (500 sccm). Obtained WS2 single crystals characterized by optical microscope, Raman and photoluminescence analysis. Optical microscope analysis demonstrated that triangular WS2 domains with single phase crystal structure are formed. The thickness of WS2 is 6 layers, which determined by Raman spectroscopy. Photoluminescence spectroscopy is shown on Fig. 20, which revealed a strong peak between 600-660 nm, typically for a monolayer WS2 crystal, where the band gap is equal to 1.96 eV

PMMA wet transferring of CVD graphene onto the target substrate

This paper presents the results of experiments such as the synthesis of graphene layers by CVD method on copper (Cu) foil, and then transferring process of obtained graphene layers onto target substrate. Chemical vapor deposition (CVD) method is widely used in the synthesis of graphene [1]. Obtained CVD graphene layers characterized by Raman, AFM and SEM analysis. Raman spectroscopy analysis shows D, G and 2D peaks which are related to graphene. In this research for CVD graphene transferring process the wet transfer method is used [2]. Firstly, poly methyl methacrylate (PMMA) was applied as a support layer on CVD graphene by Spin-coater. After chemical etching of copper foil, PMMA/graphene layers transferred on ITO substrate. Eventually, PMMA is dissolved by acetone. Fig.12 shows an optical image of transferred graphene flakes on ITO

ELECTRICAL AND STRUCTURAL CHARACTERIZATION OF FEW-LAYER GRAPHENE SHEETS ON QUARTZ

Despite the impressive performance and incredible promise for a variety of applications, the wide-scale commercialization of graphene is still behind its full potential. One of the main challenges is related to preserving graphene’s unique properties upon transfer onto practically desirable substrates. In this work, few-layer graphene sheets deposited via liquid-phase transfer from copper onto a quartz substrate have been studied using a suite of experimental techniques, including scanning electron microscopy (SEM), Raman spectroscopy, admittance spectroscopy, and four-point probe electrical measurements. SEM measurements suggest that the transfer of graphene from copper foil to quartz using the aqueous solution of ammonium persulfate was accompanied by unintentional etching of the entire surface of the quartz substrate and, as a result, the formation of microscopic facet structures covering the etched surface of the substrate. As revealed by Raman spectroscopy and the electrical measurements, the transfer process involving the etching of the copper foil in a 0.1Msolution of (NH4)2S2O8 resulted in its p-type doping. This was accompanied by the appearance of an electronic gap of 0.022 eV, as evidenced by the Arrhenius analysis. The observed increase in the conductance of the samples with temperature can be explained by thermally activated carrier transport, dominating the scattering processes

PMMA wet transferring of CVD graphene onto the target substrate

This paper presents the results of experiments such as the synthesis of graphene layers by CVD method on copper (Cu) foil, and then transferring process of obtained graphene layers onto target substrate. Chemical vapor deposition (CVD) method is widely used in the synthesis of graphene [1]. Obtained CVD graphene layers characterized by Raman, AFM and SEM analysis. Raman spectroscopy analysis shows D, G and 2D peaks which are related to graphene. In this research for CVD graphene transferring process the wet transfer method is used [2]. Firstly, poly methyl methacrylate (PMMA) was applied as a support layer on CVD graphene by Spin-coater. After chemical etching of copper foil, PMMA/graphene layers transferred on ITO substrate. Eventually, PMMA is dissolved by acetone. Fig.12 shows an optical image of transferred graphene flakes on ITO

Synthesis of WS2 crystals by the chemical vapor deposition (CVD) method on a SiO2 substrate

The synthesis and characterization of WS2 single crystals grown by chemical vapor deposition (CVD) method thru sulfurization of tungsten oxide thin layer on quartz substrate was studied. Synthesis of WS2 was carried out at 800-1000 °C in CVD system. The sulphur vapor is transported by argon gas (500 sccm). Obtained WS2 single crystals characterized by optical microscope, Raman and photoluminescence analysis. Optical microscope analysis demonstrated that triangular WS2 domains with single phase crystal structure are formed. The thickness of WS2 is 6 layers, which determined by Raman spectroscopy. Photoluminescence spectroscopy is shown on Fig. 20, which revealed a strong peak between 600-660 nm, typically for a monolayer WS2 crystal, where the band gap is equal to 1.96 eV