Misfit strain relaxation via misfit dislocation generation was observed in hetero-epitaxially grown (Al,In)GaN layers on free-standing semi-polar (11•2) GaN substrates. Cross-section transmission electron microscope images revealed misfit dislocation arrays at alloy hetero-interfaces, with the misfit dislocation line direction and Burgers vector parallel to [1¯1•0] and [11•0], respectively. The misfit dislocation structure was consistent with plastic relaxation by dislocation glide on the (00•1) plane. Since (00•1) was the only slip plane, the plastic relaxation was associated with tilt of the epitaxial (Al,In)GaN layers. The tilt, measured via high-resolution X-ray diffraction, could be used to quantify the relaxation.

Partial Strain Relaxation via Misfit Dislocation Generation at Heterointerfaces in (Al,In)GaN Epitaxial Layers Grown on Semipolar (11¯12) GaN Free Standing Substrates. A.Tyagi, F.Wu, E.C.Young, A.Chakraborty, H.Ohta, R.Bhat, K.Fujito, S.P.DenBaars, S.Nakamura, J.S.Speck: Applied Physics Letters, 2009, 95[25], 251905