High-temperature diffusion of beryllium in AlN as an area to solve problem of $p$-type doping and reduce intensity of optical absorption

Single-crystal aluminum nitride (AlN) is a promising material for development of ultraviolet optoelectronic and power instruments due to a wide band gap ($E_g\approx$ 6.1 eV). The design of the instrument fleet on its basis is restricted by difficulties in implementation of $p$-type doping, to a large extent due to poor knowledge of acceptor impurity properties. Traditionally used magnesium (Mg) impurity in AlN is characterized by high energy of activation and low solubility. The review considers the studies on AlN doping with beryllium (Be) – impurity with low energy of activation ($\sim$37 meV), high solubility and atomic radius close to Al. Special attention is paid to method of high-temperature diffusion of Be into single-crystal AlN, which demonstrated efficiency of Be as an acceptor. It was also shown that Be decreases the coefficient of optical absorption of AlN in a wide spectrum. The obtained data opens the path to development of $p$–$n$-structures based on AlN and design of optical instruments of ultraviolet range.