• Poeira, Ricardo Gonçalinho
• Weiss, Thomas Paul
• Redinger, Alex
• Martin Lanzoni, Evandro
• Leturcq, Renaud
• Ramírez, Omar
• Siebentritt, Susanne

Abstract

<jats:p> Doping in the chalcopyrite Cu(In,Ga)Se<jats:sub>2</jats:sub> is determined by intrinsic point defects. In the ternary CuInSe<jats:sub>2</jats:sub>, 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. CuGaSe<jats:sub>2</jats:sub>, 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)Se<jats:sub>2</jats:sub> single crystals in dependence of the gallium content. Our results show that Cu(In,Ga)Se<jats:sub>2</jats:sub> 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. </jats:p>

Topics

• impedance spectroscopy
• single crystal
• activation
• Gallium
• point defect
• p-type semiconductor
• n-type semiconductor