HEAT-TREATMENT OF GALLIUM NITRIDE CRYSTAL

PURPOSE:To promote the activation of p-type impurity for getting a sufficient amount of p-type carriers at a log doping amount, to suppress the generation of crystal defect caused by a large amount of impurities and to obtain a blue- light emitting diode having improved luminance, CONSTITUTION:A GaN epitaxial wafer 1 having an AlxGa1-xN or InyGa1-yN layer is formed by an organometallic vapor-phase growing process using ammonia as the nitrogen raw material. A p-type impurity such as Mg and Zn is doped in the growing stage to form a p-type crystal epitaxial layer. The doped p-type impurity is activated by placing the GaN epitaxial wafer 1 on a jig 2 inserted into a reaction tube 3 having a resistance heater 5 wound on the tube and heat-treating the gallium nitride crystal in nitrogen atmosphere under irradiation with ultraviolet rays using a mercury lamp 4. The ultraviolet rays have wavelengths of 200-350nm to excite the electric charge of hydrogen atom taken into the crystal together with the p-type impurity to the valence band.