Electrical behaviors for growth of LAST alloys using vapor phase deposition

The well-dispersed crystal structures of LAST (Lead Antimony Silver Tellurium) alloys grown by a vapor phase deposition method are demonstrated to have excellent electrical characteristics in this study. The atomic ratio of Pb to Te in the alloys are kept at 0.85-0.88. The distribution of component concentrations depends on the deposition temperature, and the Ag- and Sb-rich segments are fabricated at high deposition temperature. Experimental data suggest that the higher Sb content in the crystal increases carrier concentration up to ∼10¹⁹ (per cm). The electrical behavior of the crystal is n-type under Sb doping, and it was transferred into p-type once the samples are dominated by Ag doping, which also raises the mobility to a level as high as ∼10³ cm²/V. Test results of this study have indicated that both Ag and Sb elements contribute to the electrical conductivity enhancement, however, an excess amount of Ag may significantly deteriorate the electrical performance instead.