The invention discloses a method for synthesizing a
gallium phosphide polycrystal, which comprises the following steps of: charging
nitrogen into a chamber of a synthetic furnace, heating, and maintaining a
nitrogen pressure in the furnace to between 20 and 30 bar; raising the temperature of a
phosphorus furnace to between 480 and 520 DEG C, raising the temperature of the furnace to between 700 and 800 DEG C, increasing the current in an
induction coil to between 40 and 150 A, modulating the frequency to between 10 and 20 KHz and raising the temperature of an induction area; and moving a
quartz tube reactor in the
induction coil at a speed of 6.5cm / h, simultaneously raising the temperature of the
phosphorus furnace at a speed of 10 to 35 DEG C / h and performing a
gallium phosphide synthesizing process. After the
gallium phosphide synthesizing process is completed, the frequency of the
induction coil is slowly reduced to zero from the highest value and then the pressure of the syntheticfurnace is released. By adopting a medium high-frequency heating way to synthesize the
gallium phosphide, the method for synthesizing the
gallium phosphide polycrystal greatly decreases tube explodingtimes in the
gallium phosphide polycrystal synthesizing process, improves the yield and quality of the gallium phosphide polycrystal and does not easily generate an
electrode spark phenomenon and strong
electromagnetic radiation, thereby avoiding affecting the health of human bodies.