Dislocation patterning during crystal growth of semiconductor compounds (GaAs)

The phenomenon of dislocation patterning during melt growth of semiconductor compound crystals is discussed. The paper is focused on the formation of cellular structures in GaAs driven by thermomechanical stresses during the growth process. Undoped GaAs crystals show dislocation cell patterns with cell dimensions in the range 0.1 - 2 mm, orders of magnitude larger than in deformed metals. However, the correlation between cell diameter and dislocation density follows the same relation. Experimental results on the dislocation structure in GaAs were correlated with simulations of the resolved shear stress distribution based on a global temperature field simulation and scaled with the Taylor relation d=K rho(-1/2) and the similitude principle d=alpha KGb tau(-1) (d is cell diameter, rho is dislocation density, G is shear modulus, b is Burgers vector, tau is resolved shear stress, and alpha and K are proportionality factors). GaAs samples grown from a Ga rich melt with in situ control of stoichiometry show almost no dislocation patterning.