Growth of dislocation free grade Fe doped InP crystals

3-inch Fe doped dislocation-free (DF) grade (dislocation density < 500 cm/sup -2/) InP crystals were grown by the phosphorus vapor controlled liquid-encapsulated Czochralski (PC-LEC) method. By controlling the solid/liquid (S/L) interface shape and reducing the axial temperature gradient, the dislocation density of 3-inch Fe doped InP crystals below 500 cm/sup -2/ was achieved for the whole ingot. The average dislocation density per a wafer was 100 cm/sup -2/ at lowest. The dislocation density of 4-inch Fe doped InP crystals was also reduced to less than 5 /spl times/ 10/sup 3/ cm/sup -2/ by this method.