Nanowire formation during catalyst assisted chemical vapor deposition

Liu, Q. X.; Wang, C. X.; Xu, Ning; Yang, Guokun

doi:10.1103/physrevb.72.085417

Cited by 33 publications

(11 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is worthwhile to examine the different approaches. − In the approach, the free energies between two kinds of nuclei are compared. First, column-shape nuclei in contact with vapor and liquid are considered.…”

Section: Resultsmentioning

confidence: 99%

Growth of Bimodal Sn-Catalyzed CdS Nanowires by Using Tin Sulfide

Song

Kim

2014

J. Phys. Chem. C

View full text Add to dashboard Cite

Sn-catalyzed CdS nanowires were grown by a physical vapor transport method by using tin sulfide as a precursor. The bimodal distribution consisting of tall/thin and short/thick nanowires is found at the growth temperatures of 250–350 °C. The tall/thin nanowires grow along ⟨0001⟩ while the short/thick nanowires grow along ⟨011̅0⟩ and all have wurtzite crystal structure. The relationships, valid in the wide range 25–150 nm in nanowire diameters, of d c = (2.64 ± 0.08)d NW for the tall/thin nanowires and of d c = (1.27 ± 0.02)d NW for the short/thick nanowires, are obtained where d c and d NW are the diameters of catalyst and nanowire, respectively. Using nucleation theory, we calculate that the energies of nucleation are quite similar for both types of nanowires, which may explain the bimodality. Both types of nanowires show prominent photoluminescence without any noticeable trace of impurity-related bands, indicating their high optical quality.

show abstract

Section: Resultsmentioning

confidence: 99%

Growth of Bimodal Sn-Catalyzed CdS Nanowires by Using Tin Sulfide

Song

Kim

2014

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…where T, r 0 , and R 0 are the temperature, the nucleus-vapor interfacial energy, and the radius of the nucleus, respectively. 9,13,19 R m and V m are the gas constant and the molar volume of the nucleus, respectively. P and P e are the vapor pressure and the equilibrium vapor pressure, respectively.…”

Section: Theorymentioning

confidence: 99%

“…[5][6][7] In the case of the formation of nanostructures, heterogeneous nucleation is much more common than homogeneous nucleation in practice, [8][9][10][11][12] and this heterogeneous process can determine the growth evolution of various nanostructures. 13,14 The classical nucleation theory-which is based on the collective, pioneering work of Volmer and Weber, 15 Farkas, 16 and Becker and D€ oring 17 -has been widely used to address various nucleation processes. 9,18 However, the actual nucleation process is more complex at the nanometer scale than indicated by the ideal description provided by the classical nucleation theory, 9,19 and some new nucleation phenomena cannot be explained by the classical nucleation theory.…”

Section: Introductionmentioning

confidence: 99%

A nanoscale temperature-dependent heterogeneous nucleation theory

Cao

Yang

2015

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

Classical nucleation theory relies on the hypothetical equilibrium of the whole nucleation system, and neglects the thermal fluctuations of the surface; this is because the high entropic gains of the (thermodynamically extensive) surface would lead to multiple stable states. In fact, at the nanometer scale, the entropic gains of the surface are high enough to destroy the stability of the thermal equilibrium during nucleation, comparing with the whole system. We developed a temperature-dependent nucleation theory to elucidate the heterogeneous nucleation process, by considering the thermal fluctuations based on classical nucleation theory. It was found that the temperature not only affected the phase transformation, but also influenced the surface energy of the nuclei. With changes in the Gibbs free energy barrier, nucleation behaviors, such as the nucleation rate and the critical radius of the nuclei, showed temperature-dependent characteristics that were different from those predicted by classical nucleation theory. The temperature-dependent surface energy density of a nucleus was deduced based on our theoretical model. The agreement between the theoretical and experimental results suggested that the developed nucleation theory has the potential to contribute to the understanding and design of heterogeneous nucleation at the nanoscale. V

show abstract

“…The theoretical aspects of NMs need to be addressed in more detail to keep up with the rapid synthetic progress. In the case of the formation of one-dimensional (1D) NMs, − several studies have explained why 1D NMs have the optimal radius, , why they grow normal to the amorphous surface, why they have the maximum aspect ratio 8 and growth kinetics involving relationships between the growth rate and the radius, and the catalytic growth of nanowires . Although these studies provided useful models to reveal certain aspects of the formation and growth of the 1D NMs, there have been few studies which attempted to explain how they form on the substrate without a catalyst and why they grow with an elongated shape in the equilibrium state.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Analysis of Non-Catalytic Growth of Nanorods on a Substrate

Kwon

2006

J. Phys. Chem. B

View full text Add to dashboard Cite

A theoretical analysis explaining the whole process of the growth of nanorods on a substrate without a catalyst is presented. Prior to the growth of the nanorods, the reaction precursors form nuclei on the substrate. The nuclei undergo cluster migration caused by the surface diffusion of adatoms on the substrate, and this migration continues until the mean free time of the adatoms is larger than surface diffusion time. The most probable mechanism by which cluster migration takes place is the one that leads to the minimization of the cluster free-energy, namely the migration of six adatoms into one fixed adatom. This cluster migration continues during several (typically smaller than 6) consecutive nuclei growth steps. After the process of cluster migration comes to an end, the nuclei grow in an isotropic manner by collection of the adatoms, until the nucleus reaches the thermodynamic size limit. The one-dimensional growth of nanorods on the nuclei, which is associated with the critical radius, begins when the reactant dose is smaller than a certain value, which is determined by the thermodynamic size limit and the mass transport parameter. The mass transport of the reaction precursors leads to the expansion of the radius and elongation of the height of the nanorods, and the growth rate of the height is greater than that of the radius. This difference in the growth rate causes the aspect ratio to increase with increasing growth time. By comparing the experimental data in the literature (ZnO nanorods), the presented analysis explains well the noncatalytic growth of nanorods on a substrate.

show abstract

Nanowire formation during catalyst assisted chemical vapor deposition

Cited by 33 publications

References 26 publications

Growth of Bimodal Sn-Catalyzed CdS Nanowires by Using Tin Sulfide

Growth of Bimodal Sn-Catalyzed CdS Nanowires by Using Tin Sulfide

A nanoscale temperature-dependent heterogeneous nucleation theory

Theoretical Analysis of Non-Catalytic Growth of Nanorods on a Substrate

Contact Info

Product

Resources

About