Diffusion of light elements in 4H-and 6H-SiC

Deuterium and lithium were introduced in p-type SiC by implantation of 20 k eV H-2(+) or 30 keV Li-7(+) ions in order to form a diffusion source. The s amples were subsequently annealed in vacuum in the temperature range 400-70 0 degrees C for 0.25 to 16 h. Secondary ion mass spectrometry (SIMS) was us ed to measure the deuterium and the lithium distribution after heat treatme nts. Both deuterium and lithium readily decorate the bombardment-induced de fects in the vicinity of the ion implantation profile and they are also tra pped, most likely by residual boron impurities, during diffusion into the b ulk. An effective diffusion coefficient, reflecting the dissociation of tra pped lithium, with an activation energy of 2.1 eV is extracted for lithium diffusion in p-type 6H SIG. Furthermore, a capture radius for trapping (mos t likely by boron) of deuterium is estimated as 10 Angstrom. (C) 1999 Elsev ier Science S.A. All rights reserved.