Thermodynamic properties of SnO2/GaAs core/shell nanofiber

Abstract

We provide a comprehensive computational investigation concerning the effects of confinement and temperature on the thermodynamic properties of cylindrical core/shell quantum dots with a large band offset. This model can also be applied to hollow cylindrical quantum dots or nanofibers. Within the framework of the effective mass approximation, we solve the Schrödinger equation analytically in two bands model, determining the energies of all excited states. Following Boltzmann–Gibbs distribution and introducing the canonical partition function, energy states are used to evaluate the thermodynamic properties: the mean energy, heat capacity, entropy, and Helmholtz free energy. Our numerical calculation shows that all thermodynamic properties depend on the temperature, the size of the dot, and the shell thickness. According to our numerical results, it is found that in the narrow shell case, the heat capacity shows a Schottky-like anomaly at low temperatures, but this effect disappears for small values of core radius. Another important conclusion, is that the determination of the Helmholtz free energy makes it possible to predict the thermodynamic stability of quantum dots. We also show that the competition between the temperature, the core dimension, and the shell thickness influences the thermodynamic stability. Despite the simplicity of our approach, our study can be considered as a useful information source and as an excellent qualitative indicator for understanding the thermodynamic properties of quantum dots.