scholarly journals Excitonic absorption and defect-related emission in three-dimensional MoS2 pyramids

Nanoscale ◽  
2022 ◽  
Author(s):  
M. Negri ◽  
L. Francaviglia ◽  
D. Kaplan ◽  
V. Swaminathan ◽  
G. Salviati ◽  
...  

In this work, we study the excitonic absorption and cathodoluminescence emission of MoS2 micro-pyramids grown by chemical vapor deposition on SiO2 substrates, obtained at room and cryogenic temperatures.

1992 ◽  
Vol 114 (3) ◽  
pp. 735-742 ◽  
Author(s):  
Y. T. Lin ◽  
M. Choi ◽  
R. Greif

A study has been made of the deposition of particles that occurs during the modified chemical vapor deposition (MCVD) process. The three-dimensional conservation equations of mass, momentum, and energy have been solved numerically for forced flow, including the effects of buoyancy and variable properties in a heated, rotating tube. The motion of the particles that are formed is determined from the combined effects resulting from thermophoresis and the forced and secondary flows. The effects of torch speed, rotational speed, inlet flow rate, tube radius, and maximum surface temperature on deposition are studied. In a horizontal tube, buoyancy results in circumferentially nonuniform temperature and velocity fields and particle deposition. The effect of tube rotation greatly reduces the nonuniformity of particle deposition in the circumferential direction. The process is chemical-reaction limited at larger flow rates and particle-transport limited at smaller flow rates. The vertical tube geometry has also been studied because its symmetric configuration results in uniform particle deposition in the circumferential direction. The “upward” flow condition results in a large overall deposition efficiency, but this is also accompanied by a large “tapered entry length.”


1988 ◽  
Vol 116 ◽  
Author(s):  
R.A. Rudder ◽  
S.V. Hattangady ◽  
D.J. Vitkavage ◽  
R.J. Markunas

Heteroepitaxial growth of Ge on Si(100) has been accomplished using remote plasma enhanced chemical vapor deposition at 300*#x00B0;C. Reconstructed surfaces with diffraction patterns showing non-uniform intensity variations along the lengths of the integral order streaks are observed during the first 100 Å of deposit. This observation of an atomically rough surface during the initial stages of growth is an indication of three-dimensional growth. As the epitaxial growth proceeds, the diffraction patterns become uniform with extensive streaking on both the integral and fractional order streaks. Subsequent growth, therefore, takes place in a layer-by-layer, two-dimensional mode. X-ray photoelectron spectroscopy of the early nucleation stages, less than 80 Å, show that there is uniform coverage with no evidence of island formation.


2014 ◽  
Vol 122 ◽  
pp. 285-288 ◽  
Author(s):  
Zhuchen Liu ◽  
Zhiqiang Tu ◽  
Yongfeng Li ◽  
Fan Yang ◽  
Shuang Han ◽  
...  

2011 ◽  
Vol 1348 ◽  
Author(s):  
Jian Lin ◽  
Miroslav Penchev ◽  
Guoping Wang ◽  
Rajat K Paul ◽  
Jiebin Zhong ◽  
...  

ABSTRACTIn this work, we report the synthesis and characterization of three dimensional heterostructures graphene nanostructures (HGN) comprising continuous large area graphene layers and ZnO nanostructures, fabricated via chemical vapor deposition. Characterization of large area HGN demonstrates that it consists of 1-5 layers of graphene, and exhibits high optical transmittance and enhanced electrical conductivity. Electron microscopy investigation of the three dimensional heterostructures shows that the morphology of ZnO nanostructures is highly dependent on the growth temperature. It is observed that ordered crystalline ZnO nanostructures are preferably grown along the <0001> direction. Ultraviolet spectroscopy indicates that the CVD grown HGN layers has excellent optical properties. A combination of electrical and optical properties of graphene and ZnO building blocks in ZnO based HGN provides unique characteristics for opportunities in future optoelectronic devices.


2012 ◽  
Vol 528 ◽  
pp. 14-17
Author(s):  
Peng Zhan Sun ◽  
Hong Wei Zhu

Carbon nanotube (CNT) sponges are three-dimensional frameworks of interconnected CNTs with great potentials in composite and environmental applications. CNT sponges with lateral sizes of centimeters have been prepared through chemical vapor deposition (CVD), and their compressive mechanical properties are studied. To gain deep insight on the microstructure and how CNTs are connected within the sponges, we propose a simple theoretical model to understand the arrangement as well as the interconnection of CNTs. The mechanical properties of CNT sponges can be well explained and predicted using this model.


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