PhD Wim Deferme

1
PhDWim Deferme

• 09-05-2007

2
Contents

• H2/O2-termination
• TOF measurements
• Hall measurements
• KFM Berlin
• HCL/NH3
• Plan of experiments
• XPS
• Ellipsometry
• Attachment of DNA (Sylvia)

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Time Of Flight

• Time Of Flight

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Time Of Flight

• Time-of-Flight technique gives information
• Charge transport, characterized by mobility
  and saturation velocity
• Sample quality, doping
• Trapping kinetics related to defects and
  impurities.
• Influence of oxygen during hydrogenation on
  charge transport, defects/impurities, .

5
Time Of Flight

• 0V, 180 mJ, filter (50nm Al on quartz ? to reduce
  power)

• Positive peak ? hole depletion layer

6
Time Of Flight

• Hydrogenation ??Oxidation
• Negative Voltage (-1 to -5V), 180 mJ

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Time Of Flight

• A comparison is made between oxidised and
  hydrogenated diamond layers. (CU 0,5pF x
  2,5V/um 1,2510-12)
• Qoxi 0,510-12 ltlt CU ? small signal TOF
• Qhydr 1.210-11 gtgt CU ? SCLC mode (space
  charge limited current)

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Time Of Flight

• Hydrogenation ??Oxidation
• Positive Voltage (-1 to -5V), 180 mJ

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Conclusion TOF

• 1) Oxidised sample
• ? Surface states at surface bandgap (1.4 eV
  above VBM)
• ? Trapping
• 2) Hydrogenated sample
• ? No surface states due to dangling bonds at
  surface
• ? Less Trapping
• ? SCLC-mode

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Electroluminescence

• http//lumumba.uhasselt.be/wimdef/PhD/TOF/E6-A/fo
  tokes/geoxideerd/
• http//lumumba.uhasselt.be/wimdef/PhD/TOF/E6-A/fo
  tokes/gehydrogeneerd/

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Hall Measurements
Vacuum 2x10-5 Torr

• Temp 300C (3,3 1/C)
• ? 170C (5,9 1/C)
• ? 400C (2,5 1/C)
• ? 150C (6,7 1/C)
• ? 300C (3,3 1/C)

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Hall Measurements
Sheet Resisitivity

• cooling from 300K higher sheet resistivity
• heating from 300K higher sheet resistivity
  (adsorbates desorbe)
• cooling from 400K or heating from 170K big jump
  _at_ 300K ???
• no big difference between 0 and 1

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Hall Measurements
Carrier density

• cooling from 300K stable carrier density
  (little increase??)
• heating from 300K big jump _at_ 300K for 0 and
  4, not for 1

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Hall Measurements
Hall Mobility

• cooling from 300K decrease of Hall Mobility
  (ionized impurity scattering)
• heating from 300K decrease of Hall Mobility
  (phonon scattering)
• 0 and 4 sample go to nearly 0 cm²/Vs _at_ 170K
• 1 sample is 15 cm²/Vs _at_ 170K

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Discussion Model
H2/O2 sample C(001)-2x1H
KFM (Berlin)
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Contents

• H2/O2-termination
• TOF measurements
• Hall measurements
• KFM Berlin
• HCL/NH3
• Plan of experiments
• XPS
• Ellipsometry
• Attachment of DNA (Sylvia)

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Overview PhD

• Topic Growth and surface termination of single
  crystal (100) CVD diamond layers for use in
  (bio)-electronic applications.
• Purpose plasma technique to create linker
  between diamond substrate and DNA/molecules

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Overview PhD

• Growth thin (µm), atomically flat single
  crystal layers ? AFM/STM
• ?
• Hydrogenation H2/O2-treatment (0-1)
• 1) STS-XPS-SIMS-UPS-Hall
• 2) TOF KFM
• 3) Overview article ???

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Overview PhD

• Chlorination XPS and ellipsometry proof that
  some chlorine WAS on the surface. But very
  instable.
• ?
• Amine-treatment XPS and ellipsometry

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Chlorination
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Plan of Experiments

• 11 SC (100) samples (6 old / 5 Anna)
• Hydrogenation (fixed conditions ASTeX3)
• Chlorine / Amino termination
• 400 sccm Ar
• 20 sccm H2
• 120 sccm HCl (/- 20) for 5 minutes
• 60 Watt
• 120 mbar
• Switch of HCl and add NH3 (different
  concentrations/times/.)

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Plan of Experiments

• 6 samples for XPS (Milos-Parijs)
• 5 samples for DNA attachment (Sylvia/Veronique)
• If good conditions are found
• Ellipsometry Berlin
• Hall Measurements
• TOF