The Verneuil method lies in the shorter wavelength region of the spectrum and the crystals are violet. Experiments show that the color crystals acquire as a result of ennoblement is resistant to any action of light, temperature, and radiation that occurs in nature.
Combination of different methods implies the change of the valence of chromo-phores or their positioning in the structure of corundum, as well as dissolution of foreign phases followed by diffusion distribution of their components.
For instance, the conditions of a positive action of different factors on sapphire (0.01–0.15% Ti and 0.03–0.6% Fe) have been reported: heating in vacuum furnace up to 1,770–1,870 К, isothermal annealing during 24–30 h, and fast cooling  . Off-grade samples acquired transparency and blue color. Gamma-irradiation with a dose of 2 ⋅ 10 6 rad during 2 h stimulated either the gain of dark-amber color for some sam-ples or weakening of the intensity of dark-blue color in other cases.
Although there are lots substrates which are regarded as potential materials to replace sapphire substrate, it is still dominated in the substrates (for GaN LED growth) market, because of its reasonable price and relatively low mismatch. Zhongju is capable of processing substrates according to customer needs. Currently, our sapphire substrate productions ranges from 2 to 12 inches with high quality and accurate orientation.
ShanXiZhongJuJingKe Semiconductor Co., Ltd
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