Sublimation growth crucibles

FIGURE 1 Sublimation growth crucibles (a) single-wall graphite type and (b) double-wall type. 

The modified Lely process. Despite the high crystalline quality that may be obtained with the Lely method, it has never been considered an important technique for future commercial exploitation on account of the low yield and irregular sizes. In the modified Lely process, which is a seeded sublimation growth process, these problems are overcome, though at the price of a considerably lower crystalline quality. In the modified Lely technique, SiC powder or lumps of SiC are placed inside a cylindrical graphite crucible. The crucible is closed with... 

One of the methods of growing bulk GaN is a sublimation method [1-3], In this method, the source GaN powder and a seed crystal or a substrate facing the source are loaded in a crucible. Upon heating the crucible, the source powder sublimates and recrystallises onto the seed crystal or on the substrate. When a system needs a reaction gas such as NH3 for growth, the system is not a sublimation but a VPE system. Now, a 4-inch SiC wafer grown by a sublimation method is commercially available [4],... 

Solution growth utilises the ability of a solvent, such as Fe or Ca3N2, to take a solute into solution at a reduced temperature and precipitate the solute at an even lower temperature. The solution is contained in a crucible, and like the sublimation technique, the crucible generally fails during the lengthy growth experiments required to obtain crystals of appreciable size. 

In 1978, Tairov and Tsvetkov [24] reported a sublimation technique to produce SiC boules for device application. They produced an 8 mm diameter by 8 mm long boule of SiC on a seed crystal placed within a graphite crucible. In a further study, growth of SiC boules up to 14 mm diameter and 18 mm in length were obtained [15]. 

Sublimation method with spontaneous nucleation (mass crystallization). Crystal growth is carried out in cylindrical graphite crucibles (Fig. 14). Powder silicon carbide is used as a source material. Crucibles are heated in cylindrical furnaces with resistive or inductive heating. Growth proceeds in an inert atmosphere (argon, helium) at a temperature of 2500-... 

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