Diffusion of alkali metals in SiC

Diffusion of lithium, sodium and potassium in SiC has been studied by secondary ion mass spectrometry. The alkali metal diffusion sources have been introduced by ion implantation. Subsequent anneals have been carried out in vacuum or in Ar atmosphere in the temperature range 700 degrees C - 1500 degrees C for 5 min to 16 h. The bombardment-induced defects in the vicinity of the ion implanted profile are readily decorated by the implanted. In the bulk, the diffusing alkali metals are most likely trapped and detrapped at boron and/or other defects during diffusion. The diffusivity of the studied alkali metals decreases as the mass increases, Li+<Na+<K+, but the sodium mobility in SiC is substantial already at 1100 degrees C.