Abstract
Single crystalline GaN was grown on c-plane free-standing GaN seeds via fluid transport by the ammonothermal method. Ammonothermal growth was carried out in an ammonobasic solution with a metallic Ga nutrient placed in a lower-temperature zone. The thickest film obtained so far is ∼45 µm, which was grown on the N-face of the seed. The growth interface contained numerous voids and defects, whereas the microstructure close to the surface was greatly improved. The major defects close to the surface were mixed-character threading dislocations. The estimated threading dislocation density was low-109 cm-2 level at the free surface of the N-face.