scholarly journals Probing the Optical Properties of MoS2 on SiO2/Si and Sapphire Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 740 ◽  
Author(s):  
Tao Han ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Shupeng Chen ◽  
Wei Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Vapor ◽  
Peak Shift ◽  
Peak Position ◽  
Absorption Capacity ◽  
Exciton Peak ◽  
Monolayer Mos2 ◽  
Si Substrate ◽  
Sapphire Substrates ◽  
Pl Spectrum

As an important supplementary material to graphene in the optoelectronics field, molybdenum disulfide (MoS2) has attracted attention from researchers due to its good light absorption capacity and adjustable bandgap. In this paper, MoS2 layers are respectively grown on SiO2/Si and sapphire substrates by atmospheric pressure chemical vapor deposition (APCVD). Atomic force microscopy, optical microscopy, and Raman and photoluminescence spectroscopy are used to probe the optical properties of MoS2 on SiO2/Si and sapphire substrates systematically. The peak shift between the characteristic A1g and E12g peaks increases, and the I peak of the PL spectrum on the SiO2/Si substrate redshifts slightly when the layer numbers were increased, which can help in obtaining the layer number and peak position of MoS2. Moreover, the difference from monolayer MoS2 on the SiO2/Si substrate is that the B peak of the PL spectrum has a blueshift of 56 meV and the characteristic E12g peak of the Raman spectrum has no blueshift. The 1- and 2-layer MoS2 on a sapphire substrate had a higher PL peak intensity than that of the SiO2/Si substrate. When the laser wavelength is transformed from 532 to 633 nm, the position of I exciton peak has a blueshift of 16 meV, and the PL intensity of monolayer MoS2 on the SiO2/Si substrate increases. The optical properties of MoS2 can be obtained, which is helpful for the fabrication of optoelectronic devices.

SYNTHESIS AND OPTICAL PROPERTIES OF THE MULTILAYER STARLIKE ZnO NANOSTRUCTURES

2011 ◽  
Vol 25 (08) ◽  
pp. 1143-1148 ◽  
Author(s):  
PYINGHUA WANG ◽  
XINGCHANG WANG ◽  
AIHUA WANG ◽  
BINGLIN ZHANG ◽  
YONGTIAO TIAN ◽  
...  
Keyword(s):  
Optical Properties ◽  
Zinc Acetate Dihydrate ◽  
Chemical Vapor ◽  
Hexagonal Wurtzite Structure ◽  
Zno Nanostructures ◽  
X Ray Diffraction ◽  
Acetate Dihydrate ◽  
Zno Nanostructure ◽  
Pl Spectrum ◽  
Source Materials

A novel multilayer starlike ZnO nanostructure has been successfully synthesized on a Si (111) substrate at 600°C by chemical vapor deposition using Zn and zinc acetate dihydrate as the source materials. The morphology, structure, and optical properties are investigated by field emission scanning electron microscopy, X-ray diffraction, Raman and photoluminescence (PL) spectrum, respectively. The results show that the multilayer starlike ZnO nanostructures have hexagonal wurtzite structure. The room-temperature PL spectrum shows the dominant green band peak and the weak UV peak. The possible growth mechanism of the multilayer starlike ZnO nanostructures is also discussed.

The synthesis of 3D InN architectures via chemical vapor deposition and their optical properties

RSC Advances ◽  
2016 ◽  
Vol 6 (18) ◽  
pp. 14958-14963 ◽  
Author(s):  
Yunxuan Dong ◽  
Shunxi Tang ◽  
Hang Cui ◽  
Jian Zhang ◽  
Qiliang Cui
Keyword(s):  
Optical Properties ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Self Organization ◽  
Si Substrate

Two types of 3D InN microstructures were prepared via different self-organization processes in the up- and downstream regions of the Si substrate.

scholarly journals Direct observation of the CVD growth of monolayer MoS2 using in situ optical spectroscopy

2019 ◽  
Vol 10 ◽  
pp. 557-564 ◽  
Author(s):  
Claudia Beatriz López-Posadas ◽  
Yaxu Wei ◽  
Wanfu Shen ◽  
Daniel Kahr ◽  
Michael Hohage ◽  
...  
Keyword(s):  
Real Time ◽  
Optical Spectroscopy ◽  
Chemical Vapor ◽  
Semiconductor Materials ◽  
Transition Metal Dichalcogenide ◽  
Monolayer Mos2 ◽  
In Situ Study ◽  
Sapphire Substrates ◽  
Cvd Growth

Real-time monitoring is essential for understanding and precisely controlling of growth of two-dimensional transition metal dichalcogenide (2D TMDC) materials. However, it is very challenging to carry out such studies during chemical vapor deposition (CVD). Here, we report the first, real time, in situ study of the CVD growth of 2D TMDCs. More specifically, the CVD growth of a molybdenum disulfide (MoS2) monolayer on sapphire substrates has been monitored in situ using differential transmittance spectroscopy (DTS). The growth of the MoS2 monolayer can be precisely followed by observation of the evolution of the characteristic optical features. Consequently, a strong correlation between the growth rate of the MoS2 monolayer and the temperature distribution in the CVD reactor has been revealed. Our results demonstrate the great potential of real time, in situ optical spectroscopy to assist the precisely controlled growth of 2D semiconductor materials.

scholarly journals Synthesis of SiC/SiO2 core–shell nanowires with good optical properties on Ni/SiO2/Si substrate via ferrocene pyrolysis at low temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo-Yu Chen ◽  
Chong-Chi Chi ◽  
Wen-Kuang Hsu ◽  
Hao Ouyang
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Approximate Model ◽  
Decomposition Temperature ◽  
Core Shell ◽  
Si Substrate ◽  
Hydrocarbon Gases ◽  
Shell Nanowires

AbstractIn this study, the high-density SiC/SiO2 core–shell nanowires were synthesized on the nickel coated SiO2 (100 nm)/Si substrate by chemical vapor deposition (CVD) method with ferrocene precursor at temperature 1000 °C compared to previous studies (1300–1600 °C). The present work provides an efficient strategy for the production of SiC/SiO2 nanowires with uniform morphology and good optical properties, where the Ni layer plays important roles for this fabrication at low temperature which reduces the decomposition temperature of hydrocarbon gases and improves the growth quality of SiC nanowires. The as-synthesized SiC/SiO2 nanowires consist of single crystal 3C structures as well as 3C structures with defects along [111] direction. In the photoluminescence (PL) spectrum, the SiC/SiO2 core–shell nanowires revealed an obvious blueshift. The blueshift is due to the formation of nanoscale silicon carbide polytypism caused by the stacking faults in 3C–SiC and the nanoscale polytypism also caused the transition from indirect to direct bandgap which explains why the stacking faults percentage in SiC confirmed from X-ray diffraction (XRD) is 19%, but ultimately makes the strongest emission intensity. Finally, the PL characteristics are further improved by changing the diameter of the SiC nanowire and etching and an approximate model followed by the vapor–liquid–solid (VLS) mechanism was proposed to explain the possible growth mechanism of the SiC/SiO2 nanowires.

scholarly journals The peak shift and evolution of upconversion luminescence from CsPbBr3nanocrystals under femtosecond laser excitation

RSC Advances ◽  
2017 ◽  
Vol 7 (57) ◽  
pp. 35757-35764 ◽  
Author(s):  
Qiuju Han ◽  
Wenzhi Wu ◽  
Weilong Liu ◽  
Yanqiang Yang
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Laser Excitation ◽  
Upconversion Luminescence ◽  
Peak Shift ◽  
Peak Position ◽  
Red Shift ◽  
Time Resolved ◽  
Pl Spectrum

Compared with normal PL, a red shift of upconversion PL spectrum is observed. Time-resolved PL and TA spectroscopies show FWHM and peak position are changed at various times, which suggest the existence of more than single excited state.

scholarly journals Temperature-Dependent Optical Properties of Graphene on Si and SiO2/Si Substrates

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 358
Author(s):  
Sisi Wu ◽  
Lingyu Wan ◽  
Liangmin Wei ◽  
Devki N. Talwar ◽  
Kaiyan He ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Near Infrared ◽  
Infrared Region ◽  
Peak Position ◽  
Monolayer Graphene ◽  
Ultraviolet Region ◽  
Si Substrate ◽  
Temperature Dependent ◽  
Si Substrates

Systematic investigations are performed to understand the temperature-dependent optical properties of graphene on Si and SiO2/Si substrates by using a variable angle spectroscopic ellipsometry. The optical constants of graphene have revealed changes with the substrate and temperature. While the optical refractive index (n) of monolayer graphene on Si exhibited clear anomalous dispersions in the visible and near-infrared region (400–1200 nm), the modification is moderate for graphene on SiO2/Si substrate. Two graphene sheets have shown a pronounced absorption in the ultraviolet region with peak position related to the Van Hove singularity in the density of states. By increasing the temperature from 300 K to 500 K, for monolayer graphene on Si, the n value is gradually increased while k decreased. However, the optical constants [n, k] of monolayer graphene on SiO2/Si exhibited unpredictable wave variations. In the wavelength range of 400–1200 nm, an experiential formula of a like-Sellmeier equation is found well suited for describing the dispersions of graphene on Si and SiO2/Si substrates.

scholarly journals Fabrication and Characterization of MoS2/h-BN and WS2/h-BN Heterostructures

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1114
Author(s):  
Tao Han ◽  
Hongxia Liu ◽  
Shupeng Chen ◽  
Yanning Chen ◽  
Shulong Wang ◽  
...  
Keyword(s):  
Preparation Method ◽  
Chemical Vapor ◽  
Local Strain ◽  
Optical Microscope ◽  
Peak Position ◽  
Emission Peak ◽  
Large Area ◽  
Vdw Heterostructure ◽  
Pl Spectrum

The general preparation method of large-area, continuous, uniform, and controllable vdW heterostructure materials is provided in this paper. To obtain the preparation of MoS2/h-BN and WS2/h-BN heterostructures, MoS2 and WS2 material are directly grown on the insulating h-BN substrate by atmospheric pressure chemical vapor deposition (APCVD) method, which does not require any intermediate transfer steps. The test characterization of MoS2/h-BN and WS2/h-BN vdW heterostructure materials can be accomplished by optical microscope, AFM, Raman and PL spectroscopy. The Raman peak signal of h-BN material is stronger when the h-BN film is thicker. Compared to the spectrum of MoS2 or WS2 material on SiO2/Si substrate, the Raman and PL spectrum peak positions of MoS2/h-BN heterostructure are blue-shifted, which is due to the presence of local strain, charged impurities and the vdW heterostructure interaction. Additionally, the PL spectrum of WS2 material shows the strong emission peak at 1.96 eV, while the full width half maximum (FWHM) is only 56 meV. The sharp emission peak indicates that WS2/h-BN heterostructure material has the high crystallinity and clean interface. In addition, the peak position and shape of IPM mode characteristic peak are not obvious, which can be explained by the Van der Waals interaction of WS2/h-BN heterostructure. From the above experimental results, the preparation method of heterostructure material is efficient and scalable, which can provide the important support for the subsequent application of TMDs/h-BN heterostructure in nanoelectronics and optoelectronics.

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