Self-organizing structures in immiscible crystals

TL;DR

This paper investigates the self-organizing structures formed during spinodal decomposition in immiscible PbTe/CdTe systems, using a kinetic Monte Carlo model to replicate experimental morphologies and understand the roles of different diffusion mechanisms.

Contribution

It introduces a comprehensive kinetic Monte Carlo model that combines bulk and surface diffusion with anisotropic mobility to explain diverse self-organizing structures in immiscible crystal systems.

Findings

Model reproduces experimentally observed structures.

Different diffusion mechanisms dominate in various multilayer configurations.

The shape and type of structures depend on diffusion processes and layer thickness.

Abstract

Spinodal decomposition process in the system of immiscible PbTe/CdTe compounds is analyzed as an example of a self-organizing structure. The immiscibility of the constituents leads to the observed morphological transformations like anisotropy driven formation of quantum dots and nanowires, and to the phase separation at the highest temperatures. Proposed model accomplishes bulk and surface diffusion together with the anisotropic mobility of material components. We analyze its properties by kinetic Monte Carlo simulations and show that it is able to reproduce all of the structures observed experimentally in the process of PbTe/CdTe growth. We show that studied mechanisms of dynamic processes play different role in the creation of zero--, one--, two-- and finally three-dimensional structures. The shape of grown structures is different for relatively thick multilayers when bulk diffusion cooperates with the anisotropic mobility, in annealed structure when isotropic bulk diffusion only decides about the process and finally for thin multilayers when surface diffusion is the most decisive factor. We compare our results with experimentally grown systems and show that proposed model explains the diversity of observed structures.