Defect energy formalism for CALPHAD thermodynamics of dilute point defects: Theory

Defects in semiconducting compounds regulate charge carrier density and, consequently, the electrical properties, directly impacting the performance of electronic devices such as thermoelectrics, transistors, and solar cells. While traditionally, the Gibbs energy for defective compounds has been developed empirically, this study introduces a theoretical framework that directly connects defect energetics at electronic and atomic levels to a universally parameterized Gibbs energy function in the dilute range. This universal parameterization enables a consistent description of Gibbs energy across varying coexistence conditions, accommodating different chemical potentials and Fermi levels. This formalism for defect energy represents a significant advancement in the first-principles parameterization of the thermodynamics of defective compounds.