Electrical properties of lithium-implanted layers on synthetic diamond

Lithium implantation (40 and 50 keV; doses of 2 x 10(16) and 4 x 10(16) cm(-2)) has been performed in several synthetic and natural diamond crystals at room temperature (RT) and 850-900 degrees C (high temperature (HT) implantation). In contrast with the case of the RT implantation, the HT implantation did not result in radiation-induced surface graphitization. The samples implanted at RT and 850 degrees C were subsequently annealed at 900 degrees C. Comparison of the electrical properties of the doped crystals shows the dependence of the electrical activation on the annealing temperature. Thermal emf measurements have established that the conductivity is n-type.