PhD Wim Deferme

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PhD Wim Deferme

• 17-03-2005

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Contents

• Growth
• B-doping
• Single crystal
• Hydrogenation
• Contact-angle
• FTIR
• AFM
• Article
• Perspective
• Chlorination
• B-doping
• Influence of Oxygen

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Growth (B-doped)

• Growth of B-doped (100) diamond layers.

• Conditions 6000 W
• between 135 and 200 Torr
• 1000 gas flow in total
• between 0,5 and 4 of CH4
• between 100 and 1000 ppm TMB
• temperature between 750 and 1100C

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Growth (B-doped)

• The first step is to change the concentration
  of methane from 0,5 to 4. The best layers were
  grown at 0,5.
• The next step is to change the pressure so
  influence of temperature on the growth can be
  investigated. We changed the pressure from 135
  Torr up to 195 Torr in steps of 15 Torr.
• It can be seen in next SEM images that 195 Torr
  is the best pressure for growing flat layers.

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Growth (B-doped)
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Growth (B-doped)

• The last step is to change the amount of TMB
  during growth. We changed the amount of TMB from
  100 ppm up to 1000 ppm.
• PTIS-measurements show no B-peak because
  B-concentration is too high to be seen by PTIS.
  Resistance measurements give 20 kOhm for the
  1000ppm B-doped layer.
  To be sure about the amount of
  Boron Hall measurements.

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Growth (single)

• 700 Watt
• 500 sccm H2
• 1,5 sccm CH4
• between 120 and 170 Torr
• between 770 C and 830 C
• 5 hours

New holder to reduce edge effects.
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Growth (single)
Etching because atomic hydrogen is much more in
plasma than CH4 (0,3). Go to higher methane
concentrations.
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Hydrogenation

• First step of the surface termination cycle.
• Characterization
• Contact Angle
• FTIR
• AFM
• Conditions hydrogenation
• 500 Watt
• 500 sccm H2
• 700 C
• 60 Torr

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Hydrogenation

• contact angle measurements

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Hydrogenation

• PTIS-measurements

Also seen in substrate?? Maybe hydrogen on top
of window of detector??
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Chlorination

• Conditions 50 sccm HCl, 15 sccm Ar, 25 Watt,
  1,4 10-1 mbar, 5 minutes.
• This sample is in Eindhoven for XPS.

Contact angle 84 degrees. Surface is
hydrophobic.
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Article

• Role of hydrogen-oxygen treatment on the surface
  electronic structure of (100) CVD diamond.
• 2 regions flat and amorphous
• flat region metallic conduction (Bobrov)
• amorphous region is important

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Article
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Article
Bobrov et al. PRB 68 (2003)
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Article
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Article

• O-doped 2 regions
• 2x1 reconstructed region metallic conduction
  (0,45 eV)
• Amorphous region bandgap of 3,4 eV.
• not O-doped no conductivity after annealing
  because amorphous region is not conductive
  anymore.

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Perspective

• Growth of B-doped layers with less and more ppm
  in the gas phase. Check incorporation with Hall
  measurements.
• Chlorination of single crystal diamond with
  different conditions.
• XPS in Eindhoven
• AFM in Eindhoven
• Contact Angle KHLim
• Surface coverage _at_ synchrotron (X-ray Geert -gt
  to small)
• Article STM at LT to investigate the influence
  of oxygen.

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Hydrogenation

• AFM picture