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Changing the World through Creative Research

Selective area growth of GaN using polycrystalline r-alumina as a mask for discrete micro-GaN array

Journal
Crystal Growth & Design
Date
2022.03.02
Abstract

For commercialization of micro-LED, which has been considered as a next-generation display technology, a novel growth template named sapphire nanomembrane was introduced by our research group, previously. However, not only growth condition, but also transfer of discrete micro-LED onto other substrate was limited due to undesired growth at the bottom substrate region between the membranes. Here, we introduce a new selective area growth technology using amorphous alumina as a growth mask material. Since amorphous alumina consists of the same material with the sapphire substrate, it would not cause contamination or unintentional doping issue, which occasionally caused by Si based mask materials. During growth of GaN in MOCVD, surface region of amorphous alumina layer which used as a growth mask, was crystallized into polycrystalline g-alumina through 'random nucleation and growth’ process while the other region crystallized into single crystalline a-alumina through 'solid phase epitaxy’ process. Thereafter, GaN hardly grew on polycrystalline g-alumina owing to the large difference in growth rates between GaN islands which grew on different grains of polycrystalline g-alumina. Due to suppressed growth of GaN on polycrystalline g-alumina, highly enhanced selective growth of micro-GaN array on sapphire nanomembranes could be achieved.

Reference
Crystal growth design 22, 1770-1777 (2022)
DOI
http://dx.doi.org/10.1021/acs.cgd.1c01363