Radiation-activated development of defective structure in type Ia diamond

A type Ia diamond crystal having nitrogen impurity in the form A, B1 and B2 centers was irradiated with 3.5 MeV electrons at successively increasing d oses of 5 x 10(16), 2 x 10(17), 4 x 10(17) and 2 x 10(18) e cm(-2) and exam ined before and after each dose using a series of methods, including positr on annihilation, EPR and optical spectroscopy in IR and visible regions. Af ter irradiation with the highest dose, a development of the visible structu re of the crystal was revealed. A detailed description of the phenomenon as well as EPR and optic studies for different irradiation doses are given. T he first results of CL studies of the as-developed structure are presented. These results include CL-topograms for different regions of the crystal as well as their appropriate CL-spectra. Possible known models of defects res ponsible for main lines in CL-spectra are considered. (C) 1999 Elsevier Sci ence S.A. All rights reserved.