Abstract: Growth conditions for self-nucleation and subsequent growth of AIN crystals by PVT are presented.The crucible module with a graphite ring is introduced to avoid adhesion of the tungsten crucible and its lid at high temperatures.With in- creasing growth temperature，the natural habit of AIN crystals changes from needle-like to prismatic. When growth tempera· ture is above 1950"C，bulk AlN crystals can be grown.Measurement of supersaturation is found to impact the crystals’size and quality.Now high quality and hexagonal prism AIN single crystals with the diameter of lmm are grown，and the largest single crystal size is 2mm in diameter.

Key words: hysical vapor transport, aluminum nitride crystal, growth temperature