Plastic relaxation of stressed semipolar AlN(10$\bar1$1) layer synthesized on a nanopatterned Si(100) substrate

Plastic relaxation of a stressed semipolar AlN(10$\bar1$1) layer synthesized on a nanopatterned Si(100) substrate has been investigated using scanning electron microscopy. It is shown that the application of a nanorelief consisting of triangular nanogrooves with inclined faces close to the Si(111) plane in a semipolar AlN layer can lead to the formation of cracks only in the direction perpendicular to a groove. Model concepts of plastic relaxation of the stressed semipolar layer are based on comparison of the threshold stress, above which cracks appear, with the thermomechanical stresses emerging because of the difference between the thermal expansion coefficients of the AlN/Si structure.