Asymmetry of the defect structure of semipolar GaN grown on Si(001)

The defect structure of a thick ($\sim$15 $\mu$m) semipolar gallium nitride (GaN) layer grown by hydride–chloride vapor phase epitaxy on a Si(001) substrate with buffer layers has been studied by transmission electron microscopy. The asymmetry of the defect structure of GaN epilayer has been revealed and analyzed. The influence of this asymmetry on the rate of decrease in the density of threading dislocations in the growing epitaxial layer is discussed.