Precipitation of single crystalline AlN from Cu-Al-Ti solution under nitrogen atmosphere

Precipitation and growth behavior of AlN from Cu-Al-Ti-N solution under the atmospheric pressure of nitrogen has been studied. The solubility of AlN in Cu flux ranges from 5 mol% to 20 mol% at the temperatures between 1700 °C and 2000 °C. The addition of the proper amount of Ti drastically enhances the solubility of AlN. Acicular crystallites and platelets of AlN precipitants, which were all water white colored, were obtained by super-cooling the Cu-Al-Ti-N solution. The largest pencil type AlN reached more than 3 mm in its length and 0.2 mm in its diameter. The axis of the pencil was c-axis of wurtzite AlN and it contained no dislocation, no diffractive defects. A platelet of AlN of which diameter exceeded 1.5 mm was also obtained by regrowth technique. Thermodynamic calculation reveals the validity of using Cu-Al-Ti-N solution for the growth of AlN.