Study of defects in LED epitaxial layers grown on the optimized hemispherical patterned sapphire substrates

In this work, we focus on the study of defects in GaN grown on an optimized hemispherical patterned sapphire substrate (PSS). It is demonstrated that the proposed patterns can on the one hand induce the formation of stacking faults, and on the other hand, reduce the strain caused by thermal misfit and lattice misfit. Consequently, the optimized hemispherical patterns work successfully for both the reduction in the number of dislocations spreading to multiple quantum wells and the improvement in surface morphology. The dominant mechanism of defect multiplication and the effects of optimized hemispherical patterns in terms of materials science and device technology are elucidated.