Intentional anisotropic strain relaxation in (112¯2) oriented Al1−xInxN one-dimensionally lattice matched to GaN

We report on (112¯2) oriented Al1−xInxN grown by low pressure metal organic vapor phase epitaxy on (112¯2) GaN templates on patterned r-plane sapphire. The indium incorporation efficiency as well as the growth rate of (112¯2) oriented layers are similar to c-plane oriented Al1−xInxN layers. Deposition of thick Al1−xInxN layers does not lead to additional roughening like in case of c-plane oriented Al1−xInxN. Independent of the thickness, the degree of relaxation of layers lattice matched in m-direction is in the range of 33%–45% in [112¯3¯]-direction. Associated with the relaxation in [112¯3¯]-direction, there is a tilt of the Al1−xInxN layers around the [11¯00] axis due to slip of threading dislocations on the basal (0001)-plane. Relaxation in m-direction is not observable for layers lattice matched in [112¯3¯] direction. The possibility to adjust the lattice parameter of AlInN in [112¯3¯] direction without changing the lattice parameter in m-direction by anisotropic strain relaxation opens up opportunities for subsequent growth of optically active structures. One possibility is to form relaxed buffer layers for GaInN quantum well structures.