The production of vacancies in type Ib diamond

Optical absorption measurements on different growth sectors of a polished slice of electron-irradiated type Ib synthetic diamond show that the vacancy concentration is almost four times higher in the high-nitrogen {111} sectors than in the low-nitrogen {115} sectors. Evidence is presented to show that the self-interstitials are trapped by nitrogen, thereby reducing the amount of correlated recombination with vacancies which occurs in the absence of nitrogen.