Effect of the beryllium acceptor impurity upon the optical properties of single-crystal AlN

The effect of high-temperature ($T$ = 1880$^{\circ}$C) diffusion of beryllium ions on the properties of single-crystal aluminum nitride is investigated. It was shown that postgrowth doping of AlN with beryllium compensates the small silicon donor centers entering the AlN lattice in an uncontrolled manner during growth. It was established that the introduction of Be into the AlN lattice leads to a decrease in the optical absorption of the latter in the visible and ultraviolet ranges. The totality of the results is explained by a shift in the position of the Fermi level, caused by the introduction of the acceptor impurity of beryllium, towards the ceiling of the AlN valence band.