Role of different kinds of superlattices on the strain engineering of GaN films grown on Si (111)

The role of the Al0.2Ga0.8N/Al0.4Ga0.6N superlattice (SL) and AlN/GaN SL on the strain engineering of GaN films on Si (111) is investigated. From Raman scattering measurements, a satellite E2 peak of GaN is observed in the sample with AlN/GaN SL. It is also found the AlN/GaN SL buffer have a better effect at the blocking of threading dislocations (TDs) while lots of dislocations annihilate at the interface of Al0.2Ga0.8N/Al0.4Ga0.6N SL and GaN. In the GaN films, TDs bend and interact with each other, leading to the relaxation of compressive stress in GaN films. The relaxation rate of compressive stress in GaN films with different SL structures is studied.