Opposing effects of stacking faults and antisite domain boundaries on the conduction band edge in kesterite quaternary semiconductors

TL;DR

This study uses hybrid density functional theory to analyze how stacking faults and antisite domain boundaries differently influence the conduction band edge in kesterite semiconductors, affecting their electronic properties.

Contribution

It reveals the opposing effects of stacking faults and antisite domain boundaries on the conduction band edge in CZTS and CZTSe, providing insights into defect-induced electronic behavior.

Findings

Stacking faults raise the conduction band edge, acting as electron barriers.

Antisite domain boundaries lower the conduction band edge, accumulating electrons.

The stability of stacking faults is higher in selenide compared to sulfide.

Abstract

We investigated stability and the electronic structure of extended defects including anti-site domain boundaries and stacking faults in the kesterite-structured semiconductors, Cu$_2$ZnSnS$_4$ (CZTS) and Cu$_2$ZnSnSe$_4$ (CZTSe). Our hybrid density functional theory calculations show that stacking faults in CZTS and CZTSe induce a higher conduction band edge than the bulk counterparts, and thus the stacking faults act as electron barriers. Antisite domain boundaries, however, accumulate electrons as the conduction band edge is reduced in energy, having an opposite role. An Ising model was constructed to account for the stability of stacking faults, which shows the nearest neighbour interaction is stronger in the case of the selenide.