This work is an experimental study of intrinsic point defects in off-stoichiometric kesterite type CZTSe by means of neutron powder diffraction. We revealed the existence of copper vacancies (VCu), various cation anti site defects (CuZn, ZnCu, ZnSn, SnZn, and CuZn), as well as interstitials (Cui, Zni) in a wide range of off-stoichiometric polycrystalline powder samples synthesized by the solid state reaction. The results show that the point defects present in off-stoichiometric CZTSe agree with the off-stoichiometry type model, assuming certain cation substitutions accounting for charge balance. In addition to the known off-stoichiometry types A–H, new types (I–L) have been introduced. For the very first time, a correlation between the chemical composition of the CZTSe kesterite type phase and the occurring intrinsic point defects is presented. In addition to the off-stoichiometry type specific defects, the Cu/Zn disorder is always present in the CZTSe phase. In Cu-poor/Zn-rich CZTSe, a composition considered as the one that delivers the best photovoltaic performance, mainly copper vacancies, ZnCu and ZnSn anti sites are present. Also, this compositional region shows the lowest degree of Cu/Zn disorder.
Intrinsic point defects in off-stoichiometric Cu2ZnSnSe4: A neutron diffraction study
Galina Gurieva, Laura Elisa Valle Rios, Alexandra Franz, Pamela Whitfield, Susan Schorr; Intrinsic point defects in off-stoichiometric Cu2ZnSnSe4: A neutron diffraction study. J. Appl. Phys. 28 April 2018; 123 (16): 161519. https://doi.org/10.1063/1.4997402
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