Evaluation of the interface of thin GaN layers on c - and m -plane ZnO substrates by Rutherford backscattering

Lattice distortion at the interfaces between thin GaN layers with ∼400 nm in thickness and ZnO substrates with non-polar m -plane (10-10) and polar c -plane (0001) is studied using Rutherford backscattering/ion channeling techniques. The interface between GaN/ m -plane ZnO is aligned clearly to m -axis, indicating no lattice distortion, while between GaN/ c -plane ZnO causes the lattice distortion in the GaN layer due to the piezoelectric field. The range of distortion exceeds ∼90 nm from the interface of GaN/ c -plane ZnO. These results are confirmed by x-ray diffraction and reflection high energy electron diffraction studies.