How much gallium do we need for a p-type Cu(In,Ga)Se2?
Doping in the chalcopyrite Cu(In,Ga)Se2 is determined by intrinsic point defects. In the ternary CuInSe2, both N-type conductivity and P-type conductivity can be obtained depending on the growth conditions and stoichiometry: N-type is obtained when grown Cu-poor, Se-poor, and alkali-free. CuGaSe2, o...
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Veröffentlicht in: | APL materials 2022-06, Vol.10 (6), p.061108-061108-7 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Doping in the chalcopyrite Cu(In,Ga)Se2 is determined by intrinsic point defects. In the ternary CuInSe2, both N-type conductivity and P-type conductivity can be obtained depending on the growth conditions and stoichiometry: N-type is obtained when grown Cu-poor, Se-poor, and alkali-free. CuGaSe2, on the other hand, is found to be always a P-type semiconductor that seems to resist all kinds of N-type doping, no matter whether it comes from native defects or extrinsic impurities. In this work, we study the N-to-P transition in Cu-poor Cu(In,Ga)Se2 single crystals in dependence of the gallium content. Our results show that Cu(In,Ga)Se2 can still be grown as an N-type semiconductor until the gallium content reaches the critical concentration of 15%–19%, where the N-to-P transition occurs. Furthermore, trends in the Seebeck coefficient and activation energies extracted from temperature-dependent conductivity measurements demonstrate that the carrier concentration drops by around two orders of magnitude near the transition concentration. Our proposed model explains the N-to-P transition based on the differences in formation energies of donor and acceptor defects caused by the addition of gallium. |
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ISSN: | 2166-532X 2166-532X |
DOI: | 10.1063/5.0091676 |