PSI - Group
The thin diamond in program

Accelerator Ion Beam Modification of diamond
Thin diamond single crystals

Staff : SH Connell, CM Levitte, M Rebak, E Sideras-Haddad, IZ Machi,
DB Rebuli.
Students :  A. Naran, L Mkhonza
Collaborators : P Aggerholm (Aarhus), J.E. Butler (NRL-Washington)

We have a thin single crystal diamond program.
Various methods are used.
  1. Implant with MeV C ions, anneal, etch out the buried damaged layer. We can make
    from 1 - 10 um foils, On channeling, they have minimum yields of about 20%,
    so there is some residual damage.
  2. Laser ablation. This method allows a "frame" to remain, for support of the thin region.
    5mm diameter is easily achieved, and about 30 um thickness is possible.
  3. Thermal chemisorption. Mn or Stainless steel pellets are placed in contact with the diamond
    under slight pressure and high at temperature. This method achieves an excellent surface finish,
    and can also leave a frame for support. We get similar thicknesses as the previous method.
  4. Mechanical polishing - Important intial preparation. Recod is a 5um diamond. Suffers from plastic
    deformation at the edges. Polishing also leaves subsurface damage
  5. Combinations of the methods can be used.
  6. The 1st method can be deployed in its complimentary mode to remove material.
    A rather good surface finish is also achieved in this case.
The physics of these processes are is studied, as well as being applied to the development of targets
for the next generation of Ion Beam Analysis studies on diamond.

These special thin single crystals are also supplied to collaborators and colleagues overseas for joint experiments.

Example of First technique and an Experiment
The diamond is implanted to a dose that cause the damage to exceed threshold
for non-recovery in the Bragg peak area. Then its annealed to recover the
overlayer and drive the buried damage layer to amorphous carbon.

This electrically conductive layer is then etched electrolytically,
allowing the damaged layer to be removed.

The following is an experiment of the ttype "transmission channeling forward recoil
elastic scattering" to detect bonded oxygen alignment with atomic rows on the rear surface

The kinematic location of the forward scattered oxygen is shown by the inset.

Finally, the rocking curve for forward scattering of oxygen confirms the model of oxygen
surface bonding.