Stress relaxation in the GaN/AlN multilayers grown on a mesh-patterned Si(111) substrate

300 x 300 mu m(2) crack-free GaN/AlN multilayers of 2 mu m in thickness have been successfully grown on the Si(111) substrate patterned with the SixNy mesh by metal-organic chemical-vapor deposition. The in-plane stress exhibits a U-shape distribution across the "window" region, supported by the Raman shift of the GaN E-2(TO) mode. This indicates a stress relaxation abruptly occurring near the edge of the window region due to the freestanding surface (1101) or (1122). The in-plane stress is almost relaxed at the corner of the window region due to three freestanding surfaces (1101), (1122), and (1011). The maximum in-plane stress is located near the surface of the multilayers at the center of the window region, supported by the Raman measurements and the failure observations. The role of the SixNy mesh in the stress relaxation is discussed. (c) 2005 American Institute of Physics.