Growth, structure and field emission characteristics of petal like carbon nano-structured thin films

Srivastava, Sanjay K.; Shukla, Anupam; Vankar, V. D.; Kumar, Vikram

doi:10.1016/j.tsf.2005.07.283

Cited by 116 publications

(64 citation statements)

References 28 publications

(33 reference statements)

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“…Multilayer graphene sheets along with the MWCNTs were grown by MPECVD technique on catalyst (iron)-coated n-Si (100) substrate [21]. A thin film of Al metal of thickness *6 nm was used as an interlayer beneath the Fe catalyst film (*10 nm thick) coated on Si substrate by thermal evaporation at a base pressure *5 9 10 -6 torr.…”

Section: Methodsmentioning

confidence: 99%

Microwave plasma CVD-grown graphene–CNT hybrids for enhanced electron field emission applications

Kaushik

Shukla

2014

Appl. Phys. A

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The growth and electron emission characteristics were investigated from a hybrid structure of multiwalled carbon nanotubes (MWCNTs) and multilayer layer graphene (MLG) deposited on silicon substrate coated with iron catalyst and an interlayer of aluminium. The hybrid structures were synthesized in a two-step process by microwave plasma-enhanced chemical vapour deposition technique. The formation of MWCNTs takes place by absorption and precipitation of carbon radicals into the catalyst particles. Thereafter, ample carbon forms MLG on tip of the MWCNTs resulting in a MLG-MWCNTs hybrid nanostructure. MLG was observed to grow branching out of the tips and sidewalls of the MWCNTs and is expected to attach by Van der Walls bonds. Transmission electron microscopy and micro-Raman spectroscopy confirmed the crystalline nature of the hybrid structures. Electron emission studies were carried out using a diode-type field emission setup. The enhancement factor was found to be *3,500 for bare MWCNTs, *4,070 to *5,000 for hybrid structures and *6,500 for N-doped MLG-MWCNTs hybrid structures. Modification in the defects structure and enhancement of emission sites are suggested to be responsible for the increase of the field emission characteristics.

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Section: Methodsmentioning

confidence: 99%

Microwave plasma CVD-grown graphene–CNT hybrids for enhanced electron field emission applications

Kaushik

Shukla

2014

Appl. Phys. A

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“…The details of the experimental setup are described elsewhere [18]. In this study, oxidized Fe film of ~ 10 nm thickness on Si-substrates was used as a catalyst.…”

Section: Methodsmentioning

confidence: 99%

Effect of hydrogen plasma treatment on the growth and microstructures of multiwalled carbon nanotubes

Srivastava

Kumar

2010

Nano-Micro Lett

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The effect of hydrogen plasma treatment of iron oxide films on the growth and microstructure of carbon nanotubes (CNTs) by microwave plasma enhanced chemical vapor deposition process has been investigated. Microwave plasma was characterized in-situ using optical emission spectrometer. Morphology of the films was examined by scanning electron microscopy. Structural analysis was carried out by high resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray spectroscopy (EDS) and micro-diffraction attachments. It is found that oxide films without H 2 plasma pretreatment or treated for lesser time resulted in CNT films with high percentage of carbonaceous particles and with embedded particles/nanorods distributed discontinuously in the cavity of the nanotubes. The embedded particles were found to be of iron carbide (Fe-C) as confirmed by HRTEM, EDS and micro-diffraction analysis. Experimental observations suggested that the iron oxide particles had poor catalytic action for CNT growth and in-situ reduction of oxide clusters to Fe by hydrogen plasma plays a key role in discontinuous filling of the nanotubes by the catalytic particles. [12][13][14] have been used to synthesize CNTs. CVD methods (both thermal and plasma enhanced) are reliable in producing multiwalled CNTs (MWNTs) with proper control over the process parameters. Plasma enhanced CVD, however, can produce CNTs with a higher growth rate, at low temperature, and with better reproducibility. The plasma not only ionizes the gas but also causes a local surface heating [15]. Consequently, growth temperature could be significantly decreased compared to non-plasma CVD processes. In addition, the plasma atmosphere may also influence the detailed catalyst surface kinetics in many ways [16] and hence the growth of carbon nanostructures.Growth of CNTs and their microstructures depend on several parameters such as growth technique, feed gases, growth temperature, catalyst, and catalyst preparation method as well as their state (solid, liquid or vapor). In plasma assisted CVD processes, dilution gases play a critical role in the growth of CNTs and the structure of CNTs can be tailored by judicious control over gas composition [17]. In our earlier report, we investigated the effect of different dilution gases such as H 2 , NH 3 and N 2 and their different composition on the growth and microstructure of CNTs by microwave plasma enhanced CVD (MPECVD) process on Fe coated Si substrates using C 2 H 2 as feed gas [17]. Plasma pretreatment of catalyst film can also affect the growth and structure of CNTs significantly especially in a high frequency plasma process such as MPECVD. To the best of our knowledge, effect of H 2 plasma pretreatment of iron oxide films on the growth and structure of CNTs by MPECVD process have not been reported. Therefore, the motivation for the present

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“…Except the different nanostructures mentioned above, day by day new structures are being invented. For example, Srivastava et al reported a petal like carbon structure and also showed that this structure can serve as an efficient field emitter [8]. Liu et al varied the morphology of carbon fibers by varying the chemical vapor deposition (CVD) conditions [9].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of crystalline carbon nanofern-like structure by dc-PECVD and study of its electrical and field emission properties

Banerjee

Chattopadhyay

2012

Materials Research Bulletin

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Growth, structure and field emission characteristics of petal like carbon nano-structured thin films

Cited by 116 publications

References 28 publications

Microwave plasma CVD-grown graphene–CNT hybrids for enhanced electron field emission applications

Microwave plasma CVD-grown graphene–CNT hybrids for enhanced electron field emission applications

Effect of hydrogen plasma treatment on the growth and microstructures of multiwalled carbon nanotubes

Synthesis of crystalline carbon nanofern-like structure by dc-PECVD and study of its electrical and field emission properties

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