Fast growth of ultrananocrystalline diamond films by bias-enhanced nucleation and growth process in CH4/Ar plasma

Saravanan, Adhimoorthy; Huang, Bohr–Ran; Sankaran, Kamatchi Jothiramalingam; Dong, Chung‐Li; Tai, Nyan‐Hwa; Lin, I‐Nan

doi:10.1063/1.4875808

Cited by 13 publications

(10 citation statements)

References 25 publications

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“…There is no H (or H þ ) species present in CH 4 /Ar plasma. It should be noted that previous studies observed that for the UNCD films grown without bias voltage, an a-C phase was formed preferentially, 50,51 resulting in an amorphous carbon (a-C) layer that is schematically illustrated in Fig. 10(a).…”

Section: Discussionmentioning

confidence: 97%

Origin of graphitic filaments on improving the electron field emission properties of negative bias-enhanced grown ultrananocrystalline diamond films in CH4/Ar plasma

Sankaran

Huang

Saravanan

et al. 2014

Journal of Applied Physics

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Microstructural evolution of bias-enhanced grown (BEG) ultrananocrystalline diamond (UNCD) films has been investigated using microwave plasma enhanced chemical vapor deposition in gas mixtures of CH4 and Ar under different negative bias voltages ranging from −50 to −200 V. Scanning electron microscopy and Raman spectroscopy were used to characterize the morphology, growth rate, and chemical bonding of the synthesized films. Transmission electron microscopic investigation reveals that the application of bias voltage induced the formation of the nanographitic filaments in the grain boundaries of the films, in addition to the reduction of the size of diamond grains to ultra-nanosized granular structured grains. For BEG-UNCD films under −200 V, the electron field emission (EFE) process can be turned on at a field as small as 4.08 V/μm, attaining a EFE current density as large as 3.19 mA/cm2 at an applied field of 8.64 V/μm. But the films grown without bias (0 V) have mostly amorphous carbon phases in the grain boundaries, possessing poorer EFE than those of the films grown using bias. Consequently, the induction of nanographitic filaments in grain boundaries of UNCD films grown in CH4/Ar plasma due to large applied bias voltage of −200 V is the prime factor, which possibly forms interconnected paths for facilitating the transport of electrons that markedly enhance the EFE properties.

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Section: Discussionmentioning

confidence: 97%

Origin of graphitic filaments on improving the electron field emission properties of negative bias-enhanced grown ultrananocrystalline diamond films in CH4/Ar plasma

Sankaran

Huang

Saravanan

et al. 2014

Journal of Applied Physics

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“…Regarding the enhancing factor, recently, a theoretical study anticipated values of 3.7, 1.9 and 1.7 for the diamond (100)-2x1 surface, (111) and (110) surfaces (all terminated by hydrogen), respectively [14], supporting the experimentally observed values for single crystal diamond [10]. It is worth to point out that for NCD films, the enhancing factor of nitrogen addition on the growth rate can be considered only as an average effect from all {100}, {110} and {111} contributing surfaces in the film.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 62%

“…NCD films have been produced using Ar/CH 4 feeding gases [6] or through the introduction of nitrogen additive into CH 4 /H 2 gas mixtures [5,[7][8][9]. For example, it was recently reported that a high growth rate 2.4 µm/h was achieved for ultrananocrystalline diamond films grown by bias enhanced nucleation and growth process using CH 4 /Ar plasma [10]. It has been shown that the amount of nitrogen added into the gas phase has significant influence on the electrical properties of the produced nitrogen incorporated NCD films [11].…”

Section: Introductionmentioning

confidence: 99%

High rate growth of nanocrystalline diamond films using high microwave power and pure nitrogen/methane/hydrogen plasma

Tang

Fernandes

Granada

et al. 2015

Vacuum

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“…In contrast, the presence of sufficient amount of CH species in the plasma is necessary for retaining the small size of the diamond grains, 41 as the CH species can encapsulate the newly nucleated diamond clusters, thereby preventing them from growing bigger. Moreover, in previous studies for bias-enhanced growth of ultrananocrystalline diamond (UNCD) films, [42][43][44] it is observed that the larger C 2 abundance in the plasma leads to a higher growth rate, whereas the increase in CH concentration in the plasma induces the formation of a nanographitic phase in the films.…”

Section: Discussionmentioning

confidence: 94%

Structural modification of nanocrystalline diamond films via positive/negative bias enhanced nucleation and growth processes for improving their electron field emission properties

Saravanan

Huang

Sankaran

et al. 2015

Journal of Applied Physics

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Electron field emission (EFE) properties of nanocrystalline diamond (NCD) films synthesized by the bias-enhanced growth (beg) process under different bias voltages were investigated. The induction of the nanographitic phases is presumed to be the prime factor in enhancing the EFE properties of negative biased NCD films. Transmission electron microscopic investigations reveal that a negative bias voltage of −300 V increases the rate of growth for NCD films with the size of the grains changing from nano to ultranano size. This effect also is accompanied by the induction of nanographitic filaments in the grain boundaries of the films. The turn-on field (E0) for the EFE process then effectively gets reduced. The EFE process of the beg-NCD−300V films can be turned on at E0 = 3.86 V/μm, and the EFE current density achieved is 1.49 mA/cm2 at an applied field of 7.85 V/μm. On the other hand, though a positive-bias beg process (+200 V) results in the reduction of grain size, it does not induce sufficient nanographitic phases to lower the E0 value of the EFE process. Moreover, the optical emission spectroscopic investigation indicates that one of the primary causes that changes the granular structure of the NCD films is the increase in the proportion of C2 and CH species induced in the growing plasma. The polarity of the bias voltage is of less importance in the microstructural evolution of the films.

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Fast growth of ultrananocrystalline diamond films by bias-enhanced nucleation and growth process in CH4/Ar plasma

Cited by 13 publications

References 25 publications

Origin of graphitic filaments on improving the electron field emission properties of negative bias-enhanced grown ultrananocrystalline diamond films in CH4/Ar plasma

Origin of graphitic filaments on improving the electron field emission properties of negative bias-enhanced grown ultrananocrystalline diamond films in CH4/Ar plasma

High rate growth of nanocrystalline diamond films using high microwave power and pure nitrogen/methane/hydrogen plasma

Structural modification of nanocrystalline diamond films via positive/negative bias enhanced nucleation and growth processes for improving their electron field emission properties

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