Liquid-phase electroepitaxy: Dopant segregation

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Abstract
A theoretical model is presented which accounts for the dopant segregation in liquid‐phase electroepitaxy in terms of dopant transport in the liquid phase (by electromigration and diffusion), the growth velocity, and the Peltier effect at the substrate‐solution interface. The contribution of dopant electromigration to the magnitude of the effective segregation coefficient is dominant in the absence of convection; the contribution of the Peltier effect becomes significant only in the presence of pronounced convection. Quantitative expressions which relate the segregation coefficient to the growth parameters also permit the determination of the diffusion constant and electromigration mobility of the dopant in the liquid phase. The model was found to be in good agreement with the measured segregation characteristics of Sn in the electroepitaxial growth of GaAs from Ga‐As solutions. For Sn in Ga‐As solution at 900 °C the diffusion constant was found to be 4×10−5 cm2/s and the electromigration velocity (toward the substrate with a positive polarity) 2×10−5 cm/s at a current density of 10 A/cm2.