Stress and defect control in GaN using low temperature interlayers

In organometallic vapor phase epitaxial growth of GaN on sapphire, the role of the low-temperature-deposited interlayers inserted between high-tempera ture-grown GaN layers was investigated by in situ stress measurement, X-ray diffraction, and transmission electron microscopy. Insertion of a series o f low temperature GaN interlayers reduces the density of threading dislocat ions while simultaneously increasing the tensile stress during growth, ulti mately resulting in cracking of the GaN film. Low temperature AW interlayer s were found to be effective in suppressing cracking by reducing tensile st ress. Thr interlayer approach permits tailoring of the film stress to optim ize film structure and properties.