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Title: Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition

Abstract

The influence of N{sub 2} concentration (1%–8%) in CH{sub 4}/H{sub 2}/N{sub 2} plasma on structure and optical properties of nitrogen doped diamond (NDD) films was investigated. Thickness, roughness, and optical properties of the NDD films in the VIS–NIR range were investigated on the silicon substrates using spectroscopic ellipsometry. The samples exhibited relatively high refractive index (2.6 ± 0.25 at 550 nm) and extinction coefficient (0.05 ± 0.02 at 550 nm) with a transmittance of 60%. The optical investigation was supported by the molecular and atomic data delivered by Raman studies, bright field transmission electron microscopy imaging, and X-ray photoelectron spectroscopy diagnostics. Those results revealed that while the films grown in CH{sub 4}/H{sub 2} plasma contained micron-sized diamond grains, the films grown using CH{sub 4}/H{sub 2}/(4%)N{sub 2} plasma exhibited ultranano-sized diamond grains along with n-diamond and i-carbon clusters, which were surrounded by amorphous carbon grain boundaries.

Authors:
 [1];  [2]; ;  [3];  [4]; ;  [5];  [1];  [6];  [7]
  1. Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdansk (Poland)
  2. (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium)
  3. Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium)
  4. (Belgium)
  5. Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland)
  6. (United States)
  7. Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)
Publication Date:
OSTI Identifier:
22590781
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 24; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CHEMICAL VAPOR DEPOSITION; DIAMONDS; DOPED MATERIALS; ELLIPSOMETRY; GRAIN BOUNDARIES; METHANE; MICROWAVE RADIATION; NITROGEN; PLASMA; REFRACTIVE INDEX; ROUGHNESS; THICKNESS; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Ficek, Mateusz, E-mail: rbogdan@eti.pg.gda.pl, Institute for Materials Research, Sankaran, Kamatchi J., Haenen, Ken, IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek, Ryl, Jacek, Darowicki, Kazimierz, Bogdanowicz, Robert, Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, and Lin, I-Nan. Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition. United States: N. p., 2016. Web. doi:10.1063/1.4953779.
Ficek, Mateusz, E-mail: rbogdan@eti.pg.gda.pl, Institute for Materials Research, Sankaran, Kamatchi J., Haenen, Ken, IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek, Ryl, Jacek, Darowicki, Kazimierz, Bogdanowicz, Robert, Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, & Lin, I-Nan. Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition. United States. doi:10.1063/1.4953779.
Ficek, Mateusz, E-mail: rbogdan@eti.pg.gda.pl, Institute for Materials Research, Sankaran, Kamatchi J., Haenen, Ken, IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek, Ryl, Jacek, Darowicki, Kazimierz, Bogdanowicz, Robert, Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, and Lin, I-Nan. Mon . "Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition". United States. doi:10.1063/1.4953779.
@article{osti_22590781,
title = {Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition},
author = {Ficek, Mateusz, E-mail: rbogdan@eti.pg.gda.pl and Institute for Materials Research and Sankaran, Kamatchi J. and Haenen, Ken and IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek and Ryl, Jacek and Darowicki, Kazimierz and Bogdanowicz, Robert and Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 and Lin, I-Nan},
abstractNote = {The influence of N{sub 2} concentration (1%–8%) in CH{sub 4}/H{sub 2}/N{sub 2} plasma on structure and optical properties of nitrogen doped diamond (NDD) films was investigated. Thickness, roughness, and optical properties of the NDD films in the VIS–NIR range were investigated on the silicon substrates using spectroscopic ellipsometry. The samples exhibited relatively high refractive index (2.6 ± 0.25 at 550 nm) and extinction coefficient (0.05 ± 0.02 at 550 nm) with a transmittance of 60%. The optical investigation was supported by the molecular and atomic data delivered by Raman studies, bright field transmission electron microscopy imaging, and X-ray photoelectron spectroscopy diagnostics. Those results revealed that while the films grown in CH{sub 4}/H{sub 2} plasma contained micron-sized diamond grains, the films grown using CH{sub 4}/H{sub 2}/(4%)N{sub 2} plasma exhibited ultranano-sized diamond grains along with n-diamond and i-carbon clusters, which were surrounded by amorphous carbon grain boundaries.},
doi = {10.1063/1.4953779},
journal = {Applied Physics Letters},
number = 24,
volume = 108,
place = {United States},
year = {Mon Jun 13 00:00:00 EDT 2016},
month = {Mon Jun 13 00:00:00 EDT 2016}
}
  • Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar{endash}1%CH{sub 4} or Ar{endash}1%CH{sub 4}{endash}5%H{sub 2}, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2{endash}10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H{sub 2}. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2{endash}0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on themore » Si substrate when H{sub 2} is present in the plasma. For the case of UNCD growth from a plasma without addition of H{sub 2}, the initial nucleation occurs on an amorphous carbon layer about 10{endash}15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial. {copyright} 2001 American Institute of Physics.« less
  • Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar--1%CH{sub 4} or Ar--1%CH{sub 4}--5%H{sub 2}, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2--10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H{sub 2}. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2--0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on themore » Si substrate when H{sub 2} is present in the plasma. For the case of UNCD growth from a plasma without addition of H{sub 2}, the initial nucleation occurs on an amorphous carbon layer about 10--15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial.« less
  • CH{sub 4} and C{sub 2}H{sub 2} molecules (and their interconversion) in hydrocarbon/rare gas/H{sub 2} gas mixtures in a microwave reactor used for plasma enhanced diamond chemical vapor deposition (CVD) have been investigated by line-of-sight infrared absorption spectroscopy in the wavenumber range of 1276.5-1273.1 cm{sup -1} using a quantum cascade laser spectrometer. Parameters explored include process conditions [pressure, input power, source hydrocarbon, rare gas (Ar or Ne), input gas mixing ratio], height (z) above the substrate, and time (t) after addition of hydrocarbon to a pre-existing Ar/H{sub 2} plasma. The line integrated absorptions so obtained have been converted to species numbermore » densities by reference to the companion two-dimensional (r,z) modeling of the CVD reactor described in Mankelevich et al. [J. Appl. Phys. 104, 113304 (2008)]. The gas temperature distribution within the reactor ensures that the measured absorptions are dominated by CH{sub 4} and C{sub 2}H{sub 2} molecules in the cool periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning, and confirming the model predictions. Under standard process conditions, the study confirms that all hydrocarbon source gases investigated (methane, acetylene, ethane, propyne, propane, and butane) are converted into a mixture dominated by CH{sub 4} and C{sub 2}H{sub 2}. The interconversion between these two species is highly dependent on the local gas temperature and the H atom number density, and thus on position within the reactor. CH{sub 4}->C{sub 2}H{sub 2} conversion occurs most efficiently in an annular shell around the central plasma (characterized by 1400<T{sub gas}<2200 K), while the reverse transformation C{sub 2}H{sub 2}->CH{sub 4} is favored in the more distant regions where T{sub gas}<1400 K. Analysis of the multistep interconversion mechanism reveals substantial net consumption of H atoms accompanying the CH{sub 4}->C{sub 2}H{sub 2} conversion, whereas the reverse C{sub 2}H{sub 2}->CH{sub 4} process only requires H atoms to drive the reactions; H atoms are not consumed by the overall conversion.« less
  • Fluorinated silicon-nitride films have been prepared at low temperature (250 deg. C) by remote plasma enhanced chemical vapor deposition using mixtures of SiF{sub 4}, N{sub 2}, Ar, and various H{sub 2} flow rates. The deposited films were characterized by means of single wavelength ellipsometry, infrared transmission, resonant nuclear reactions, Rutherford backscattering analysis, and current-voltage measurements. It was found that films deposited without hydrogen grow with the highest deposition rate, however, they result with the highest fluorine content ({approx}27 at. %) and excess of silicon (Si/N ratio{approx_equal}1.75). These films also have the lowest refractive index and the highest etch rate, andmore » exhibit very poor dielectric properties. As a consequence of the high fluorine content, these films hydrolize rapidly upon exposure to the ambient moisture, forming Si-H and N-H bonds, however, they do not oxidize completely. The addition of hydrogen to the deposition process reduces the deposition rate but improves systematically the stability and insulating properties of the films by reducing the amount of both silicon and fluorine incorporated during growth. All the fluorinated silicon-nitride films deposited at hydrogen flow rates higher than 3.5 sccm resulted free of Si-H bonds. In spite of the fact that films obtained at the highest hydrogen flow rate used in this work are still silicon rich (Si/N ratio{approx_equal}1.0) and contain a considerable amount of fluorine ({approx}16 at. %), they are chemically stable and show acceptable dielectric properties.« less
  • Nanocrystalline diamond films have been synthesized by microwave plasma enhanced chemical vapor deposition using N{sub 2}/CH{sub 4} as the reactant gas without additional H{sub 2}. The nanocrystalline diamond phase has been identified by x-ray diffraction and transmission electron microscopy analyses. High resolution secondary ion mass spectroscopy has been employed to measure incorporated nitrogen concentrations up to 8{times}10{sup 20}atoms/cm{sup 3}. Electron field emission measurements give an onset field as low as 3.2V/{mu}m. The effect of the incorporated nitrogen on the field emission characteristics of the nanocrystalline films is discussed. {copyright} {ital 1997 American Institute of Physics.}