Occurrence of Natural <i>p</i> — <i>n</i> Junctions in Lead Selenide

Abstract

Single crystals of PbSe were grown from melts in sealed quartz tubes. Except for a very narrow range of initial melt compositions, stoichiometric excesses of Pb or Se in the melt resulted in crystals that were wholly n or p type, respectively. Initial composition within the critical range yielded crystals showing both p and n regions. The electrical resistivities were related to crystal compositions permitting the construction of the Pb-Se phase diagram in a narrow region about the compound PbSe. The invariant melting point for the system falls in the Se-rich region. This precludes the possibility of growing a crystal from a melt which is of stoichiometric composition throughout.