VARIABLE PERIOD VARIABLE COMPOSITION SUPPERLATTICE AND DEVICES INCLUDING SAME

摘要

An optical semiconductor device such as a light emitting diode is formed on a transparent substrate having formed thereon a template layer, such as AlN, which is transparent to the wavelength of emission of the optical device. A variable period variable composition superlattice strain relief region is provided over the template layer such that the composition of the strain relief region approaches or matches the composition of the regions contiguous thereto. For example, the Al content of the strain relief region may be tailored to provide a stepped or gradual Aluminum content from template to active layer. Strain-induced cracking and defect density are reduced or eliminated.