The composition modulation effect during spinodal decomposition of Zn_xCd_1-xTe solid solutions under conditions of energy resonance

Abstract

The Cahn-Hillard equation, previously obtained to describe the decomposition of metal solid solutions, is adapted to analyze the spinodal decomposition of A2B6 semiconductor solid solutions. The obtained differential equation is used to describe the spinodal decomposition of the ZnxCd1-xTe solid solution, which is synthesized under conditions close to the boundaries of absolutely unstable regions on the state diagram of the system. A quantitative description of the composition modulation effect that appears in the material when its growth under the indicated conditions is given. Computer simulations of the spinodal decomposition of the ZnxCd1-xTe solid solution showed that micro oscillations of the material composition are connected by the resonance phenomenon between the excess mixing energy and the energy of elastic strains arising in the inclusions of the new phase coherently conjugated with the lattice of the initial crystal. It is shown that such resonance phenomena are most intense when the conditions for the material synthesis are chosen in the immediate vicinity of the spinodal curves in the phase state diagram of the system.

Resonance of mixing energy and energy of elastic deformations during spinodal decomposition and the composition modulation effect in ZnхCd1-ХTe solid solutions

“…In this article, it is presented in full the thermodynamic and mathematical model for the spinodal decomposition of A 2 B 6 ternary semiconductor solid solutions when the deposition occurs without the stabilizing effect of a massive substrate. The findings obtained refine and supplement the results presented in the paper [12].…”

“…As a rule, the indicated parameter and its temperature dependence are found by processing the data on phase equilibria in the systems in accordance with the model of simple solutions in different approximations. Despite the limited experimental information on the state diagrams of Zn-Cd-Te systems, especially at the low-temperature interval, the solid-state interaction parameters reported in the literature do not contradict their physical meaning and correlate well with each other for A 2 B 6 systems [4,12]. Such a situation justifies the possibility of using the data from works [4,12] for modeling the process of spinodal decomposition of the solid solutions to be considered.…”

“…Despite the limited experimental information on the state diagrams of Zn-Cd-Te systems, especially at the low-temperature interval, the solid-state interaction parameters reported in the literature do not contradict their physical meaning and correlate well with each other for A 2 B 6 systems [4,12]. Such a situation justifies the possibility of using the data from works [4,12] for modeling the process of spinodal decomposition of the solid solutions to be considered. The above considerations allow us to take the following value of the parameter in the calculations ( )…”

"The resonance between the mixing energy and the elastic strain energy as the reason for the composition modulation effect appearance during the spinodal decomposition of GaInPAs solid solutions "

“…The possibility of realizing such a situation in ternary and quaternary A 3 B 5 systems was analyzed in several theoretical works [3,[5][6][7][8][9]. The results of these theoretical studies were confirmed in the description of experimental data on composition modulation effect in A 3 B 5 ternary and quaternary solid solutions.…”

“…The use of the analytical method to describe this effect in ternary solutions made it possible to explain the appearance of micro-oscillations in the composition of the layers [3,5,6]. A direct numerical solution of the Cahn-Hilliard spinodal decomposition equation made it possible to show that the phenomenon of resonance between the mixing energy of the components and the energy of elastically deformed inclusions of a new solid phase into which the material decomposes is responsible [7][8][9]. This effect is responsible for a significant increase in the amplitude of oscillations in the composition of the material to a value that can be experimentally detected.…”