The Growth of Non-polar GaN Substrate by HVPE
In this research, we obtained the non-polar GaN substrate with a thickness of 225um successfully by hydride vapor phase epitaxy(HVPE) using a three-step method which included growing a GaN thick film on the template grown by metalorganic chemical vapor deposition(MOCVD), obtaining the GaN freestanding after laser lift-off, regrowing the GaN thick film on the GaN freestanding. Low temperature photoluminescence of the thick films suggested that the strong near-band-edge(NBE) emission was increasing and the emission of basal stacking faults(BSF) was decreasing as the thickness of the grown films was increased. It was found that the intensity of the near-band-edge emission was stronger than the emission of basal stacking faults when the non-polar GaN substrate was with a thickness of 225um. Particularly, the growth machine of the non-polar GaN substrate was similar to an epitaxially laterally overgrown GaN(ELOG), however, there were not any photolithography processes during the growth process of the GaN substrate. It was easy to form voids which were useful to release stresses. Presently, we can achieve the non-polar GaN substrate with a thickness of 225um. We make sure that the maximum thickness of the non-polar GaN substrate will increase and the quality of the non-polar GaN substrate will be better in the future.
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