Anisotropic Microsegregation in the Growth of Doped III‐V‐Semiconductors from Solution

Abstract

In this paper, a consistent formulation of macro‐ and microsegregation is presented to describe dopant inhomogeneities and concentration variations in binary and multinary III‐V‐semiconductor crystals grown from metallic solution. The effective distribution and diffusion coefficients respectively are calculated by applying the classical segregation models for zone melting and are based on experimental data. From the macroscopic effective distribution coefficient keff the microscopic kinetic distribution coefficient kkin is derived, which varies along a curved growth face, in particular along a macrostep. As a consequence of this surface anisotropy, the fluxes of the dissolved species through the interface vary as well and cause local changes in the liquidus distribution of species. The liquidus concentration is calculated by means of 2‐dimesional numerical simulations. The extracted liquidus concentration along the interface combined with the locally changing kinetic distribution coefficient allows the calculation of the solidus concentration along the macrostep. The result is the consistent description of microsegregation as a result of an anisotropic interface on a µm‐scale and the macro‐segregation on a mm‐ or cm‐scale. This could be tested experimentally in a diffusion dominated growth regime under microgravity.