Stability and electronic properties of planar defects in quaternary I2-II-IV-VI4 semiconductors

TL;DR

This study explores how chemical substitutions affect the stability and electronic properties of planar defects in quaternary I2-II-IV-VI4 semiconductors, aiming to prevent defect formation and improve electronic performance.

Contribution

It provides insights into how specific chemical substitutions influence the stability of stacking faults and their electronic effects in quaternary semiconductors.

Findings

Ag substitution reduces stacking fault stability.

Cd and Ge substitutions promote stacking fault formation.

Cd reduces electron barrier energy, Ag increases electron capture.

Abstract

Extended defects such as stacking faults and anti-site domain boundaries can perturb the band edges in Cu$_2$ZnSnS$_4$ and Cu$_2$ZnSnSe$_4$, acting as a weak electron barrier or a source for electron capture, respectively. In order to find ways to prohibit the formation of planar defects, we investigated the effect of chemical substitution on the stability of the intrinsic stacking fault and metastable polytypes and analyze their electrical properties. Substitution of Ag for Cu makes stacking faults less stable, whereas the other substitutions (Cd and Ge) promote their formation. Ge substitution has no effect on the electron barrier of the intrinsic stacking fault, but Cd substitution reduces the barrier energy and Ag substitution makes the stacking fault electron capture. While Cd substitution stabilizes the stannite structure, chemical substitutions make the primitive-mixed CuAu (PMCA) structure less stable with respect to the ground-state kesterite structure.