Effect of Al content on the microstructure in GaN grown on Si by MOVPE

Abstract

PACS 68.37. Lp, 81.05.Ea, 81.15.Gh III-nitride films with different layer structures are grown on Si(111) substrate by metalorganic vapor phase epitaxy. Inserting an Al x Ga 1Àx N (x $ 0:08) layer in the structure can effectively reduce the dislocations in the GaN top film, which is assessed by transmission electron microscopy experiment. Secondary ion mass spectrometry and cathodoluminescence studies demonstrate that the variation of the dislocation density is directly related to the distributions of the Al concentration in the epilayer.