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Title: Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition

Abstract

Layered self-standing diamond films, consisting of an upper layer, buffer layer, and a lower layer, were fabricated by fluctuating the ratio of methane to hydrogen in high power dc arc plasma jet chemical vapor deposition. There were micrometer-sized columnar diamond crystalline grains in both upper layer and lower layer. The size of the columnar diamond crystalline grains was bigger in the upper layer than that in the lower layer. The orientation of the upper layer was (110), while it was (111) for the lower layer. Raman results showed that no sp{sup 3} peak shift was found in the upper layer, but it was found and blueshifted in the lower layer. This indicated that the internal stress within the film body could be tailored by this layered structure. The buffer layer with nanometer-sized diamond grains formed by secondary nucleation was necessary in order to form the layered film. Growth rate was over 10 {mu}m/h in layered self-standing diamond film fabrication.

Authors:
; ; ; ; ; ;  [1]
  1. School of Material Science and Engineering, University Science and Technology, Beijing, Beijing 10083 (China)
Publication Date:
OSTI Identifier:
20853954
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 25; Journal Issue: 1; Other Information: DOI: 10.1116/1.2409940; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHEMICAL VAPOR DEPOSITION; DIAMONDS; EPITAXY; FABRICATION; FILMS; HYDROGEN; LAYERS; METHANE; NUCLEATION; PLASMA JETS; SEMICONDUCTOR MATERIALS; STRESSES

Citation Formats

Chen, G. C., Dai, F. W., Li, B., Lan, H., Askari, J., Tang, W. Z., and Lu, F. X.. Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition. United States: N. p., 2007. Web. doi:10.1116/1.2409940.
Chen, G. C., Dai, F. W., Li, B., Lan, H., Askari, J., Tang, W. Z., & Lu, F. X.. Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition. United States. doi:10.1116/1.2409940.
Chen, G. C., Dai, F. W., Li, B., Lan, H., Askari, J., Tang, W. Z., and Lu, F. X.. Mon . "Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition". United States. doi:10.1116/1.2409940.
@article{osti_20853954,
title = {Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition},
author = {Chen, G. C. and Dai, F. W. and Li, B. and Lan, H. and Askari, J. and Tang, W. Z. and Lu, F. X.},
abstractNote = {Layered self-standing diamond films, consisting of an upper layer, buffer layer, and a lower layer, were fabricated by fluctuating the ratio of methane to hydrogen in high power dc arc plasma jet chemical vapor deposition. There were micrometer-sized columnar diamond crystalline grains in both upper layer and lower layer. The size of the columnar diamond crystalline grains was bigger in the upper layer than that in the lower layer. The orientation of the upper layer was (110), while it was (111) for the lower layer. Raman results showed that no sp{sup 3} peak shift was found in the upper layer, but it was found and blueshifted in the lower layer. This indicated that the internal stress within the film body could be tailored by this layered structure. The buffer layer with nanometer-sized diamond grains formed by secondary nucleation was necessary in order to form the layered film. Growth rate was over 10 {mu}m/h in layered self-standing diamond film fabrication.},
doi = {10.1116/1.2409940},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 1,
volume = 25,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • Detailed methodology and results are presented for a two-dimensional (r,z) computer model applicable to dc arc jet reactors operating on argon/hydrogen/hydrocarbon gas mixtures and used for chemical vapor deposition of micro- and nanocrystalline diamond and diamondlike carbon films. The model incorporates gas activation, expansion into the low pressure reactor chamber, and the chemistry of the neutral and charged species. It predicts the spatial variation of temperature, flow velocities and number densities of 25 neutral and 14 charged species, and the dependence of these parameters on the operating conditions of the reactor such as flows of H{sub 2} and CH{sub 4}more » and input power. Selected outcomes of the model are compared with experimental data in the accompanying paper [C. J. Rennick et al., J. Appl. Phys. 102, 063309 (2007)]. Two-dimensional spatial maps of the number densities of key radical and molecular species in the reactor, derived from the model, provide a summary of the complicated chemical processing that occurs. In the vortex region beyond the plume, the key transformations are CH{sub 4}{yields}CH{sub 3}{r_reversible}C{sub 2}H{sub 2}{r_reversible}large hydrocarbons; in the plume or the transition zone to the cooler regions, the chemical processing involves C{sub 2}H{sub x}{r_reversible}(CH{sub y} and CH{sub z}), C{sub 3}H{sub x}{r_reversible}(CH{sub y} and C{sub 2}H{sub z}), (C{sub 2}H{sub y} and C{sub 2}H{sub z}){r_reversible}C{sub 4}H{sub x}{r_reversible}(CH{sub y} and C{sub 3}H{sub z}). Depending on the local gas temperature T{sub g} and the H/H{sub 2} ratio, the equilibria of H-shifting reactions favor C, CH, and C{sub 2} species (in the hot, H-rich axial region of the plume) or CH{sub 2}, C{sub 2}H, and C{sub 2}H{sub 2} species (at the outer boundary of the transition zone). Deductions are drawn about the most abundant C-containing radical species incident on the growing diamond surface (C atoms and CH radicals) within this reactor, and the importance of chemistry involving charged species is discussed. Modifications to the boundary conditions and model reactor geometry allow its application to a lower power arc jet reactor operated and extensively studied by Jeffries and co-workers at SRI International, and comparisons are drawn with the reported laser induced fluorescence data from these studies.« less
  • Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {l_brace}100{r_brace} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was {approx}530 deg. C during diamond deposition. The depositedmore » films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/{mu}m) and high current-density (1.6 mA/cm{sup 2}) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.« less
  • Heat conduction in a free-standing chemical vapor-deposited polycrystalline diamond film has been investigated by means of combined front and rear photoacoustic signal detection techniques and also by means of a mirage' photothermal beam deflection technique. The results obtained with the different techniques are consistent with a value of [alpha] = (5.5 [+-] 0.4) [times] 10[sup [minus]4]m[sup 2][center dot]s[sup [minus]1] for thermal diffusivity, resulting in a value of k -(9.8 [+-] 0.7) [times] 10[sup 2]W m[sup [minus]1]. K[sup [minus]1] for thermal conductivity when literature values for the density and heat capacity for natural diamond are used. 25 refs., 7 figs.
  • The efficacy of various non-diamond carbon films as precursors for diamond nucleation on unscratched silicon substrates was investigated with a conventional microwave plasma-enhanced chemical vapor deposition system. Silicon substrates were partially coated with various carbonaceous substances such as clusters consisting of a mixture of C[sub 60] and C[sub 70], evaporated films of carbon and pure C[sub 70], and hard carbon produced by a vacuum arc deposition technique. For comparison, diamond nucleation on silicon substrates coated with submicrometer-sized diamond particles and uncoated smooth silicon surfaces was also examined under similar conditions. Except for evaporated carbon films, significantly higher diamond nucleation densitiesmore » were obtained by subjecting the carbon-coated substrates to a low-temperature high-methane concentration hydrogen plasma treatment prior to diamond nucleation. The highest nucleation density ([similar to]3[times]10[sup 8] cm[sup [minus]2]) was obtained with hard carbon films. Scanning electron microscopy and Raman spectroscopy demonstrated that the diamond nucleation density increased with the film thickness and etching resistance. The higher diamond nucleation density obtained with the vacuum arc-deposited carbon films may be attributed to the inherent high etching resistance, presumably resulting from the high content of [ital sp][sup 3] atomic bonds. Microscopy observations suggested that diamond nucleation in the presence of non-diamond carbon deposits resulted from carbon layers generated under the pretreatment conditions.« less
  • Selected area deposition of diamond films on silicon substrates was successfully achieved using the patterned Pt layer as a nucleation inhibitor in the chemical vapor deposition process. The planar diamond film array thus made possesses good electron field emission properties, that is, emission current density of (J{sub e}){sub Si}=150{mu}A/cm{sup 2} (under 23.6 V/{mu}m) and turn on field of (E{sub o}){sub Si}=10V/{mu}m. Precoating a thin Au layer (20 nm) on a Si surface further increased the emission current density to (J{sub e}){sub Au/Si}=960{mu}A/cm{sup 2} (under 23.6 V/{mu}m) with (E{sub o}){sub Au/Si}=10V/{mu}m. The effective work functions ({phi}) estimated by Fowler{endash}Nordheim plots ofmore » the I{endash}V characteristics are ({phi}){sub Si}=0.059eV and ({phi}){sub Au/Si}=0.085eV. The emission properties of both planar diamond film arrays satisfy the requirement for applying as the electron emitters in the flat panel displays. {copyright} {ital 1997 American Institute of Physics.}« less