It was shown that new electrically active defects could develop in the homo-epitaxial layer grown on Ib diamond substrates, related to the increase of the dislocation density. Deep centers, which were able to compensate the B acceptors, specially when the growth process allows B incorporation below 1015/cm3 like achieved in the samples, were identified after heating in an inert gas ambient both from photo-induced current transient spectroscopy and changes in Schottky diode current-voltage characteristics. Cathodoluminescence spectra were used to monitor the bands and excitonic lines, some of them being specific of dislocations. A correlation was demonstrated between the onset of properties characteristic of a compensated semiconductor and the increase of signals associated to dislocations in cathodoluminescence spectra. These modifications were thermally driven only when the samples were laid on a heating holder immerged in an inert gas, suggesting that a temperature gradient induced an additional stress which finally led to plastic relaxation of the tensile strain in the homo-epitaxial layer by an increase of the dislocation density. New deep centers being simultaneously created in this degradation process, the problem of overcoming the onset of these defects for implementing high voltage devices was discussed.

Acceptor Compensation by Dislocations Related Defects in Boron Doped Homoepitaxial Diamond Films from Cathodoluminescence and Schottky Diodes Current Voltage Characteristics. P.Muret, M.Wade: Physica Status Solidi A, 2006, 203[12], 3142-6