Large Optical Polarization Anisotropy Due To Anisotropic In-Plane Strain In M-Plane Gainn Quantum Well Structures Grown On M-Plane 6h-Sic

We investigated the optical polarization anisotropy of m-plane GaInN/GaN quantum well structures on m-plane SiC and bulk GaN substrates. On bulk GaN, the degree of polarization increases with increasing indium content according to the larger strain-induced separation of the topmost valence bands. On m-plane SiC, however, we observe constantly large polarization ratios of around 90% and more. From an x-ray strain state analysis and calculations of the valence band energies, we find that an anisotropic strain of the GaN buffer layer leads to a very strong separation of the topmost valence bands resulting in a large degree of polarization. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702786]