Growth of AiN single crystals

摘要

Aluminum nitride is a wurtzite structure III-V compound, although epitaxial layers of zincblende structure AlN have been made. AlN melts congruently at 2750 deg with dissociation pressure of 9 atmospheres. Boules of AlN have been successfully grown by a sublimation-recondensation technique at 2300 deg employing tungsten crucibles. Growth rates of 0.3 mm per hour were attained at 1 bar pressure of N_2, and crystals up to 22 mm long have been grown. An analysis of the growth process shows that the 9.75eV dissociation energy of N_2 is the limiting factor in the growth rate. The growth rate is predicted to depend on the N_2 pressure, but no experiments in this area have yet been concluded. The most satisfactory crucible material found so far for growing AlN is single crystal tungsten.