科研之友
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摘要
Cu2ZnGeS4 is a promising semiconductor that has potentially wide applications. Intrinsic stability and electronic properties of the Cu2ZnGeS4 surface are investigated in this work. The surfaces are stabilized by defects that are found to show diverse physics from that of the bulk. Under Cu-rich conditions, the acceptor-like Cu-enriched and Zn-deficient defects dominate both in the bulk and on the surface. However, under Cu-poor conditions, acceptor-like Cu-deficient defects dominate in the bulk, whereas donor-like Cu-deficient and Zn-enriched defects dominate on the surface. Therefore, an n-p type inversion occurs at the area between the bulk and surface. Moreover, among the possible surface configurations, only the 2Zn(Cu) ((112) over bar) surface does not generate surface states in the band gap. Hence, the Cu-poor condition is proposed if Cu2ZnGeS4 acts as a solar cell material. The results can also be generalized to other quaternary chalcogenides.
