Development of Dislocation Density Analysis Code for Annealing Process of Single Crystal Ingot.

Abstract

Ingot annealing is indispensable process for GaAs single crystal to improve its electric characteristics. One of the technical problems of GaAs ingot annealing is the increase of dislocation density during its annealing process which affects the performance of electronic devices. A computer code was developed for dislocation density evaluation of a single crystal ingot during annealing process. In this computer code, the temperatures in a single crystal ingot are used as input data, which were obtained from transient heat conduction analysis of an ingot. A dislocation kinetics model called Haasen-Sumino model was used as the consitutive equation. In this model, creep strain rate is related to the dislocation density, and this model extended to the multiaxial stress state was incorporated into a finite element elastic creep analysis cede for axisymmetric bodies. Dislocation density analyses were performed using this computer code for GaAs ingots of 4- or 6-inches diameter, and time variations of dislocation density and equivalent shear stress and residual stress after the ingot annealing were obtained by this computer code.