Vertical Bridgman growth of sapphire crystals, with thin-neck formation process

Abstract

A new technique is proposed in the traditional vertical Bridgman growth of sapphire crystals, in which thin-neck formation follows the initial seeding. Low-angle grain boundaries generated at the periphery of the seeding interface were eliminated at the thin neck, and c-axis sapphire crystals with main bodies free from low-angle grain boundaries were grown.

Analysis of thermal stress through finite element analysis during vertical Bridgman crystal growth of 2 inch sapphire

“…VB 공정은 기존 HEM과 비교하여 hot zone 내 온도구배와 결정성장 속도의 제어가 용이하 며 [7][8][9], 성장시 hot zone 하단에 저온부가 형성되므로 CZ, KY 등의 공정과 비교하여 대류의 영향에서 자유로 운 장점이 있다. 또한 기판에 쓰이는 c-축 방향으로 직 접 성장이 가능하고 대구경화에 용이하여 향후 LED용 사파이어 기판 제조에 적극 활용될 것으로 기대된다 [10].…”

Vertical Bridgman growth of sapphire—Seed crystal shapes and seeding characteristics

“…It was well known that the difficulty of reproducible seeding for single-crystal growth can be strongly dependent on the shape and size of the seed crystal. For the traditional VB method, however, there are a few reports [14,15] on the shape and size of seed crystals, and on the details of the seeding process when they are used.…”