Bridgman Solidification of Concentrated GaInSb Alloys with Variable Growth Rate

Abstract

Experimental works and numerical simulations on concentrated Ga1−xInxSb alloys directional solidification at high crucible pulling rates, show a damping solutal effect on the thermally driven convection which leads to a significant increase of the chemical heterogeneity of the sample and of the solid‐liquid interface curvature. Analytical calculations which give a quantitative description of the solutal effect, show that the melt convection damping can be avoided if low pulling rates of the crucible are used for the growth process. A Bridgman growth method, which uses a variable pulling rate in order to reduce the damping solutal effect and to improve the axial chemical homogeneity of the sample, is numerically investigated. The growth process can be started at high pulling rates which are reduced progressively during the solidification. From the numerical modeling, it is found that the axial and radial variations of solute concentration as well as the interface curvature are maintained at lower values when variables pulling rates are used for Bridgman solidification of high doped alloys.