50 ∼ 100 mm diameter iron-doped InP crystal was grown by in-situ phosphorous injection synthesis liquid encapsulated Czochraski (LEC) method. Samples were characterized by high speed photoluminescence (PI) mapping and Etch pit density (EPD) mapping method. The perfection of these samples were studied and compared. 100 mm diameter InP single crystals were successfully developed by rapid P-injection in-situ synthesis LEC method. The EPD across the ingot was less than 5 × 104 cm−2, which was almost equal to the crystals of diameter 50 and 76 mm. By adjusting the thermal field and ensuring the chemical stoichiometry, InP crystals of larger diameters and good performance could be developed.