A NUMERICAL-ANALYSIS FOR THE CONVERSION PHENOMENON OF GAAS TO GAASP ON A GAP SUBSTRATE IN AN LPE SYSTEM

A computational model for the mass transport occurring during the conv ersion of GaAs to GaAsP on a GaP substrate is presented. The mass tran sport equations in the liquid and solid phases, and the equations desc ribing phase diagram constitute the governing equations. These equatio ns together with appropriate interface and boundary conditions were so lved numerically by the finite element method. Numerical solutions agr ee with experimental results and explain well the conversion phenomeno n. The conversion process is initiated by the non-equilibrium conditio n between the Ga-As-P solution and the GaAs layer and promoted by the rapid diffusion of V elements into the GaAs (GaAsP conversion) layer.