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Stress evolution in different growth mechanism of GaN grown by Na-flux method

The study found that homoepitaxial Na-flux GaN has a large stress at the interface, and the stress is released to a certain extent within 50 μm in the growth direction of the Na-flux GaN. After passing through the columnar growth region, the Na-flux GaN tends to a stress-free state finally. The columnar growth mode is produced by GaN island growth, the islands nucleate and coalescence to produce tensile stress. The Na-flux GaN undergoes a columnar growth to generate tensile stress, which offsets the residual compressive stress at the interface, which is conducive to stress release.