High-temperature diffusion of the acceptor impurity Be in AlN

The high-temperature diffusion of an acceptor impurity of beryllium (Be) into bulk single-crystal aluminum nitride (AlN) has been studied. It is shown that the introduction of Be leads to the appearance of green luminescence of AlN, which is stable at room temperature and is observed over the entire thickness of the sample. It was shown by the method of luminescence analysis that the Be diffusion process is most efficiently realized in the temperature range from 1800 to 2100$^\circ$C and is characterized by extremely high diffusion coefficients $D$ = 10$^{-7}$ cm$^2$/s and 10$^{-6}$ cm$^2$/s, respectively. It is shown that a prolonged diffusion process ($t\ge$ 1 hour) at a temperature of 2100$^\circ$C leads to concentration quenching of the luminescence of near-surface AlN layers with a thickness of $\approx$ 80 $\mu$m, which makes it possible to estimate the concentration of beryllium impurities in the near-surface layer on the order of $\sim$ 10$_{19}$ cm$^{-3}$.