Bridgman-type crystal growth

Yield Improvement and Defect Control in Bridgman-Type Crystal Growth with the Aid of Thermal Modeling... 

Nowadays, Bridgman-type crystal-growth configurations are mainly applied for the industrial production of compound semiconductors like high-quality GaAs [7,... 

Virtual crystal growth, i.e. numerical simulation of the heat- and mass-transport processes has become a standard tool for the development and optimization of academic and industrial crystal-growth processes [5,18,19]. This holds especially for the optimization of Bridgman-type crystal-growth configurations. A typical crystal growth setup implies a vast variety of coupled and interacting physicochemical processes, which have all to be taken into account as accurately as possible to... 

Now, the influence of convective gas flow on the heat transfer can be estimated for Bridgman-type crystal-growth processes carried out under high gas pressure conditions such as the growth of GaAs (3-7 bar) InP (30-40 bar) and GaP ( 80 bar). Assuming a temperature difference AT between the water-cooled vessel and the outer thermal insulation of the heaters of 100 K and a distance I of more than 5 cm one obtains for a gas pressure p > 1 bar from Eq. (5.3) a Grashof number Gr > 1000 and a Nusselt number Nu 1. 

In the following, typical tasks in the field of optimi2ation of Bridgman-type crystal-growth processes are presented where both, thermal modeling and experimental analysis, contribute. 

The control of the shape of the solid/liquid interface during the whole growth process is, in general, and not only for Bridgman-type crystal-growth processes, of great importance for several reasons ... 

The optimization of the thermal conditions in Bridgman-type crystal growth of GaAs and InP with respect to low thermal stress conditions by using numerical simulation results mainly in a reduction of the dominant type of dislocations, the so-called 60°-dislocations with curved line vectors [49]. In Table 5.4 typical dislocation densities reported for different crystals grown by Bridgman-type growth techniques are summarized. 

In Bridgman-type crystal-growth configurations one possibility to control convection and therefore the shape of the solid/liquid interface, as well as the dopant distribution, is the so-called accelerated cmcible rotation technique (ACRT). This technique was developed by Scheel [56] and has been applied especially to the Bridgman growth of CdHgTe and CdZnTe crystals, e.g. [57, 58). 

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