Codoping of sulfur and boron in CVDdiamond

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Co-doping of sulfur and boron in CVD-diamond
Rongbin Li, Xiaojun Hu, Hesheng Shen, Xianchang
He
Yang Hyun-Seok
Material science engineering
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Contents
1. Introduction
2. Experiment
3. Result and discussion
4. Conclusion
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Introduction
CVD Diamond films had been recognized as
promising materials for electronic device which
could operate at high temperatures or as
electrodes for harsh electrochemical application
P-type conductivity had been confirmed for
B-doped diamond by gas doping
N-type conductivity with high-quality electronic
device had not been obtained
Recently, sulfur had been reported to give n-type
conductivity, however, its electrical
conductivity is very low and is not suitable for
electrical devices
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Experiments
1. Diamond films were synthesized on a
single-crystal p-type Si substrate suing the
conventional microwave plasma-assisted chemical
vapor deposition (MPCVD) method

• 2. Analysis
• Auger election spectroscopy (AES)
• Particle-induced X-ray emission (PIXE)
• - Scanning electron microscopy (SEM)
• Fourier transform infrared spectrometer (FTIR)
• Two-point probe

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Result and discussion
2.31KeV
Fig. 1. (a) PIXE spectrum and (b) Auger electron
spectrum (AES main figure) of sulfur-doped
diamond
The absolute value for the sulfur content in
films was about 0.11 at. (S-doped) When
B/S-doped in the feed source gas, the sulfur
concentration increased to 0.15 at.
1. The addition of boron facilitated sulfur
incorporation into diamond
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Result and discussion
(a) undoped
(b) S-doped
(c) B/S-co-doped
Fig. 2. SEM images of diamond films

• well-faceted crystalline microstructures with
  random orientations
• cauliflower-like morphology
• Diamond grains changed into similar
  roundish-shaped ones, while the surface became
  relatively smoother.

2. Boron improved the crystalline quality of
diamond surface
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Result and discussion
Fig. 3. Resistivity curve of curve of diamond
films (a) B/S-co-doped and (b) S-doped, as a
function of inverse temperature
The linear relationship between log (R) and the
inverse temperature indicated that the
conductivity of the films was thermally
activated The activation energies of conductivity
were depending on the amount of sulfur in the
diamond
3. The conductivity of films was increased with
increasing S incorporation into diamond, and the
limited amounts of boron facilitated the
incorporation of sulfur atoms into diamond
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Conclusion
1. The addition of boron facilitated sulfur
incorporation into diamond
2. Boron improved the crystalline quality of
diamond surface
3. The conductivity activation energy of CVD
grown films decreased with increasing of S
incorporation into diamond
4. Substitutional BS in diamond might be
responsible for the donor source