Dislocation reduction in sulfur- and germanium-doped indium phosphide single crystals grown by the vertical gradient freeze process: A transient finite-element study

摘要

During the growth of indium phosphide (InP) crystals, dislocations are mostly generated in a plastically deformed crystal due to crystallographic glide caused by excessive thermal stresses. High dislocation density presented in the InP crystal can reduce the performance, lifetime, and reliability of the InP-based microelectronic and optoelectronic devices/circuits. The generation of dislocations in InP single crystals grown from the melt can be predicted by using a transient finite-element model. This model couples microscopic dislocation motion and multiplication to macroscopic plastic deformation during the crystal growth process. The temperature fields in the crystal are determined by solving the partial differential equations of heat transfer for the vertical gradient freeze (VGF) process. These temperature fields are then employed to the transient finite-element model to study the effects of doping impurities and growth parameters (i.e., imposed temperature gradient, crystal radius, and growth rate) on dislocation reduction in InP crystals grown by different VGF processes.