Theoretical study of defects Cu sub(3)SbSe sub(4): Search for optimum dopants for enhancing thermoelectric properties

• Published in: Journal of alloys and compounds Vol. 625; pp. 346 - 354
• Main Authors: Do, Dat T, Mahanti, S D
• Format: Journal Article
• Language: English
• Published: 15-03-2015
• Subjects: Antimony; Copper; Crystal defects; Dopants; Doping; Mathematical analysis; Semiconductors; Vacancies; Zinc
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2014.11.031

Cu sub(3)SbSe sub(4) is a promising thermoelectric material due to high thermopower (> 400 mu V/K) at 300 K and higher. Although it has a simple crystal structure derived from zinc blende structure, previous work has shown that the physics of band gap formation is quite subtle due to the importance of active Ione pair (5s super(2)) of Sb and the non-local exchange interaction between these and Se 5p electrons. Since for any application of semiconductors understanding the properties of defects is essential, we discuss the results of a systematic study of several point defects in Cu sub(3)SbSe sub(4) including vacancies and substitutions for each of the components. First principles calculations using density functional theory show that among variety of possible dopants, p-type doping can be done by substituting Sb with group IV elements including Sn, Ge, Pb and Ti and n-type doping can be done by replacing Cu by Mg, Zn. Doping at the Se site appears to be rather difficult. Electronic structure calculations also suggest that the p-type behavior seen in nominally pure Cu sub(3)SbSe sub(4) is most likely due to Cu vacancy rather than Se vacancy.