Stress relaxation and critical thickness for misfit dislocation formation in (10(1)over-bar0) and (30(31)over-bar) InGaN/GaN heteroepitaxy

Cathodoluminescence imaging was used to study the onset of plastic relaxation and critical thickness for misfit dislocation (MD) formation by basal plane (BP) or nonbasal plane (NBP) slip in In0.09Ga0.91N/GaN heterostructures grown on nonpolar (10 (1) over bar0) and semipolar (30 (31) over bar) substrates. Layers grown on both orientations were shown to stress relax initially via generation of NBP MDs as a result of prismatic slip on inclined m-planes. Analysis of the resolved shear stress on the two slip planes (i.e., basal and an inclined m-plane) reveals a crossover at which the resolved shear stress on the m-planes becomes larger than that on the BP. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4707160]