Effect of nonstoichiometry on conductivity type in Bridgman-grown CuInSe2

Ingots containing single crystals of CuInSe2, were grown by a vertical Bridgman method from nonstoichiometric proportions of the starting elements. In all cases, the first portion of the ingot was single-phase chalcopyrite with a uniform composition close to stoichiometry, as determined by EPMA. The conductivity type in this region, determined by hot probe, was uniformly n- or p-type and was found to correlate with the atomic proportion of indium [In], whereby p-type material occurred generally for [In] < 25 at% approx. and n-type for [In] > 25 at% approx. The last region to freeze of the ingots contained the multiphases Cu7In4, Cu9In4, Cu4In, Cu, Se, CuSe and InSe, along with undocumented apparent compounds of Cu5In3, Cu4In3 and In7Se5. (C) 1998 Elsevier Science B.V. All rights reserved.