Aug 13, 2017

Modeling of dislocation dynamics in germanium Czochralski growth

Highlights

Comprehensive computer simulation of 4-in. Czochralski germanium growth was done.
Alexander-Haasen model of dislocation density showed reasonable predictions.
Factors of dislocation density multiplication rate were considered.
Two approaches of dislocation transfer at the melt/crystal interface were employed.

Abstract

Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal.
In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

Keywords

A1. Dislocation density
A1. Computer modeling
A2. Czochralski crystal growth
B1. Germanium
Source:ScienceDirect
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