Czochralski technique

The Czochralski Technique. Pulling from the melt is known as the Czochralski technique. Purified material is held just above the melting point in a cmcible, usually of Pt or Ir, most often powered by radio-frequency induction heating coupled into the wall of the crucible. The temperature is controlled by a thermocouple or a radiation pyrometer. A rotating seed crystal is touched to the melt surface and is slowly withdrawn as the molten material solidifies onto the seed. Temperature control is used to widen the crystal to the desired diameter. A typical rotation rate is 30 rpm and a typical withdrawal rate, 1—3 cm/h. Very large, eg, kilogram-sized crystals can be grown. 

Overview of Unit Operations. To maximize the electron or hole (carrier) mobility and thus device speed, ICs are built in single-crystal substrates. Methods of bulk crystal growth are therefore needed. The most common of these methods are the Czochralski and float-zone techniques. The Czochralski technique is a crystal-pulling or melt-growth method, whereas the float-zone technique involves localized melting of a sintered bar of the material, followed by cooling and, thus, crystallization. 

For our investigations we use a single crystal of sbn doped with 0.66 mol% Cerium. It was grown by the Czochralski technique from the congruently melting composition by... 

The mineral spinel, MgA Of, was one of the first substrates tried for GaN epitaxy [8,25,35], and has been the most successful of all alternative substrates for GaN heteroepitaxy. Spinel single crystals can be grown by the Czochralski technique and substrates of modest size can be obtained commercially. The chief advantage of spinel over sapphire is that it cleaves more easily than sapphire. 

Monocrystal — A single crystal that is as perfect as possible. Monocrystals can be obtained under strictly controlled crystallization conditions, using, e.g., the Czochralski technique. In electrochemical investigation... 

The Czochralski technique shown in Figure 6 relies on the controlled withdrawal of a seed crystal from a liquid melt. As the seed is lowered into the melt, partial melting of the tip occurs, creating the liquid-solid interface required for crystal growth. As the seed is withdrawn, solidification occurs and the seed orientation is propagated into the grown material. The... 

Figure 6 Schematic diagram of the Czochralski technique as used for the growth of single-crystal GaAs...

A requirement for making YAG crystals is a homogeneous, high-purity starting material for use in the Czochralski technique. This means that the application of mechanical mixing and solid-state diffusion techniques are limited. Accordingly, a variety of synthesis techniques have been developed, most of which are sol-gel based. 

Metallic appearance. Small single crystals have been grown by a modification of the Czochralski technique Gremmelmaier, Z. Naturforsch. 11A, 463 (1956). mp 943°. Hardly attacked by mineral acids. Energy gap 0.35 ev. Electron mobility approx 33,000 cm1/volt-sec. Hole mobility 460 cm2/volt-sec. Dielectric constant 11.7. 

Single crystals of Ag8[W4016] have been obtained by the Czochralski technique. Starting material was prepared as described above. A 2.5-cm dia by... 

Oxide crystals are usually grown by the Czochralski technique, but alkali halide crystals can also be grown by this method. The perfection of these crystals is high, but the size is normally limited to 3-4 inches diameter. However, with a special... 

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