Ionic Electrodeposition of II–VI and III–V Compounds: I . Development of a Simple, Butler‐Volmer Equation‐Based Kinetic Model for Electrodeposition

Abstract

A simple kinetic model has been developed for the electrodeposition of and other 12–16 (II–VI) or 13–15 (III–V) compounds from solutions containing reducible ions of both constituents and is based upon a generalized Butler‐Volmer equation that considers ion transport limitations near the cathode. Although the deposition itself is a non‐equilibrium process, the reaction between the plated cadmium and tellurium is assumed sufficiently rapid that any infinitesimally small volume in the deposit remains in quasi‐chemical equilibrium, as defined by the equilibrium constant‐mass action expression involving the activities of the solid constituents and conservation of mass, as invoked by a unity mole fraction sum. Exponential activity coefficients are postulated consistent with “regular” solution models. Although neglecting second‐order effects such as hydrogen generation, IR and space‐charge voltage drops within the deposit, and possible phase segregation, the model yields a convenient algorithm to numerically simulate voltammetric (j‐E) curves and calculate the mole fractions and activities of cadmium, tellurium, and cadmium telluride existing at the deposit surface for any deposition potential.