scholarly journals Impact of the in situ rise in hydrogen partial pressure on graphene shape evolution during CVD growth of graphene

RSC Advances ◽  
2018 ◽  
Vol 8 (15) ◽  
pp. 8234-8239 ◽  
Author(s):  
Zewdu M. Gebeyehu ◽  
Aloïs Arrighi ◽  
Marius V. Costache ◽  
Clivia M. Sotomayor-Torres ◽  
Maria J. Esplandiu ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Hydrogen Partial Pressure ◽  
Shape Evolution ◽  
Cvd Growth

Growth to etching transformation following in situ rise in hydrogen with time results in dendritic graphene.

In Situ Observation of Nucleation and Growth of Carbon Nanotubes from Iron Carbide Nanoparticles

2008 ◽  
Vol 1142 ◽  
Author(s):  
Hideto Yoshida ◽  
Seiji Takeda ◽  
Tetsuya Uchiyama ◽  
Hideo Kohno ◽  
Yoshikazu Homma
Keyword(s):  
Carbon Nanotubes ◽  
Iron Carbide ◽  
Bulk Diffusion ◽  
Chemical Vapor ◽  
Nucleation And Growth ◽  
Atomic Scale ◽  
In Situ Observation ◽  
Transmission Electron ◽  
Cvd Growth

ABSTRACTNucleation and growth processes of carbon nanotubes (CNTs) in iron catalyzed chemical vapor deposition (CVD) have been observed by means of in-situ environmental transmission electron microscopy. Our atomic scale observations demonstrate that solid state iron carbide (Fe3C) nanoparticles act as catalyst for the CVD growth of CNTs. Iron carbide nanoparticles are structurally fluctuated in CVD condition. Growth of CNTs can be simply explained by bulk diffusion of carbon atoms since nanoparticles are carbide.

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

Low-Temperature Epitaxial Growth of IN-Situ HeavilY B-Doped Si1-xGex, Films Using Ultraclean LPCVD

1998 ◽  
Vol 533 ◽  
Author(s):  
A. Morrya ◽  
M. Sakuraba ◽  
T. Matsuura ◽  
J. Murota ◽  
I. Kawashima ◽  
...  
Keyword(s):  
Low Temperature ◽  
Partial Pressure ◽  
Epitaxial Growth ◽  
Lattice Constant ◽  
Deposition Rate ◽  
Epitaxial Films ◽  
Similar Degree ◽  
Gas Mixture ◽  
Heavy Doping

AbstractIn-situ heavy doping of B into Si1-xGex epitaxial films on the Si(100) substrate have been investigated at 550°C in a SiH4(6.0Pa)-GeH4(0.1−6.0Pa)-B2H6(1.25 ×10−5−3.75 × 10−2Pa)-H2(17–24Pa) gas mixture by using an ultraclean hot-wall low-pressure CVD system. The deposition rate increased with increasing GeH4 partial pressure, and it decreased with increasing B2H6 partial pressure only at the higher GeH4 partial pressure. As the B2H6 partial pressure increased, the Ge fraction scarcely changed although the lattice constant of the film decreased. These characteristics can be explained by the suppression of both the SiH4 and GeH4 adsorption/reactions in a similar degree due to B2H6 adsorption on the Si-Ge and/or Ge-Ge bond sites. The B concentration in the film increased proportionally up to 1022cm3 with increasing B2H6 partial pressure.

Effect of O2 Partial Pressure on Post Annealed Ba2YCU3O7-δ Thin Films

1992 ◽  
Vol 275 ◽  
Author(s):  
Julia M. PhUlips ◽  
M. P. Siegal ◽  
S. Y. Hou ◽  
T. H. Tiefel ◽  
J. H. Marshall
Keyword(s):  
Partial Pressure ◽  
Film Growth ◽  
Epitaxial Films ◽  
Pinning Force ◽  
Low Oxygen ◽  
O2 Partial Pressure ◽  
Growth Method ◽  
Lower Temperature ◽  
The Relationship

ABSTRACTEpitaxial films of Ba2YCu3O7-δ (BYCO) as thin as 250 å A and with Jc's approaching those of the best in situ grown films can be formed by co-evaporating BaF2, Y, and Cu followed by a two-stage anneal. These results extend the work on films > 2000 Å thick by R. Feenstra et al. [J. Appl. Phys. 69, 6569 (1991)]. High quality films of these thicknesses become possible if low oxygen partial pressure [p(O2) = 4.3 Torr] is used during the high temperature portion cf the anneal (Ta). The BYCO melt line is the upper limit for Ta. The use of low p(O2) shifts the window for stable BYCO film growth to lower temperature, which allows the formation of smooth films with greater microstructural disorder than is found in films grown in p(O2) = 740 Torr at higher Ta. The best films annealed in p(O2)=4.3 Torr have Jc values a factor of four higher than do comparable films annealed in P2=740 Torr. The relationship between the T required to grow films with the strongest pinning force and p(O2) is log independent of growth method (in situ or situ) over a range of five orders of magnitude of P(O2).

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