The invention relates to a method for growing
gallium phosphide single crystals. The method comprises the following steps of: preparing materials, charging, vacuumizing, filling gas, heating for dissolving,
welding seed crystals, seeding, shouldering, removing a floating needle for the first time, removing the floating needle for the second time, performing equal-
diameter control, and ending, wherein
gallium phosphide polycrystals, a floating boat, a
doping agent and
boron oxide are put into a
crucible in the material preparation process, the floating boat is made of
silicon nitride and has the internal
diameter of phi20 to 80mm, and pressure is controlled to be 1.0 to 5.0MPa (absolute pressure) after a
hearth is filled with
nitrogen. The method has the advantages that: the
diameter of the crystals is controlled by the floating boat, the density of the floating boat is between the density of the
boron oxide and the density of
gallium phosphide, the floating boat can float on a melting surface of the
gallium phosphide, and the diameter is slightly influenced by the ascending or descending of a
solid liquid interface in the floating boat due to temperature change, so the diameter of the crystals can be well controlled by controlling the rotating speed of the floating boat, the
gallium phosphide single crystals with the size of 1 to 3 inches are grown, the yield of the single crystals is improved, the
crystallization quality of the single crystals is high, and a mobility index in electrical parameters can stably reach 130-140cm<2> / v.s.