Elimination of V-shaped pits in InGaN/GaN/AlN/GaN heterostructure by metal modulation growth technique

In this paper, we have demonstrated the growth process of higher Indium content indium gallium nitride (InGaN) epitaxial layer of InGaN/GaN/AlN/GaN heterostructure without any V-shaped pits formation on the growth surface. The epitaxial InGaN with In fraction of 16%, 22% and 26% has been grown by using metal modulation growth scheme. The direct growth of relaxed InGaN structures with In content of 16% and 22% on GaN/AlN/GaN periodic layer shows higher density of V-shaped pits on the surface, as the InGaN epilayer is experienced to higher lattice relaxation and threading dislocation density. But for the 26% In mole heterostructure, the V pits are mitigated by varying the Indium fraction from 16% to 26% via 22% in bottom to top direction of the structure. The FESEM images have also confirmed the absence of any pits formation in 26% In content InGaN heterostructure, which is due to the lesser lattice relaxation and threading dislocation density. The different contents of Indium are confirmed by room temperature photoluminescence and XRD measurements. (paper)