Epitaxial relationship of semipolar s-plane (1(1)over-bar01) InN grown on r-plane sapphire

The heteroepitaxy of semipolar s-plane (1 (1) over bar 01) InN grown directly on r-plane sapphire by plasma-assisted molecular beam epitaxy is studied using transmission electron microscopy techniques. The epitaxial relationship is determined to be (1 (1) over bar 01)(InN) parallel to (1 (1) over bar 02)(Al2O3), [(1) over bar(1) over bar 20](InN) parallel to [20 (2) over bar(1) over bar](Al2O3), [1 (1) over bar0 (2) over bar](InN) similar to parallel to [02 (2) over bar1](Al2O3), which ensures a 0.7% misfit along [(1) over bar(1) over bar 20](InN). Two orientation variants are identified. Proposed geometrical factors contributing to the high density of basal stacking faults, partial dislocations, and sphalerite cubic pockets include the misfit accommodation and reduction, as well as the accommodation of lattice twist. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731788]