Diamond-based semiconductor devices offer the promise of operation at high
temperatures and under extreme radiation conditions. An essential step in
the drive towards operational diamond-based electronic devices is the
ability to controllably and reproducibly dope the diamond. Ion implantation
is the method of choice for such doping because it offers precise control of
the dopant concentration and spatially selective doping is achievable using
standard masking techniques. However, compared to silicon, the doping of
diamond is complicated by the tendency of the diamond to relax to graphite
upon thermal annealing. Furthermore, even if graphitization can be avoided,
the compensation of dopants by residual defects has proved in the past to be
a limiting factor in obtaining very high mobility material. In this paper,
we present a scheme for the effective doping of diamond using MeV
ion-implantation. For MeV ion- implantation the doped layer is deeply buried
under a cap of undamaged diamond, and so the scheme includes a method using
pulsed laser irradiation for making electrical contact to the buried layer.
We show that a boron doped layer fabricated by the MeV implantation scheme
has, after suitable annealing and removal of these compensating/trapping
defects, very high mobility and low compensation ratio. In fact, its
electrical properties are quite similar to those of natural boron-doped type
IIb diamond.