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

We report on (112̅2) oriented Al1−xInxN grown by low pressure metal organic vapor phase epitaxy on (112̅2) GaN templates on patterned r-plane sapphire. The indium incorporation efficiency as well as the growth rate of (112̅2) 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 [112̅3̅]-direction. Associated with the relaxation in [112̅3̅]-direction, there is a tilt of the Al1−xInxN layers around the [11̅00] axis due to slip of threading dislocations on the basal (0001)-plane. Relaxation in m-direction is not observable for layers lattice matched in [112̅3̅] direction. The possibility to adjust the lattice parameter of AlInN in [112̅3̅] 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. [ABSTRACT FROM AUTHOR]