The Variation of Optical Energy Gaps with Composition in Pb1xHgxS Alloy Films

Abstract

Studies of optical properties of flash evaporated Pb1−xHgxS films, in the composition range 0.07 ≦ x ≦ 0.93, show that the alloy films are formed by alloying of PbS with α‐HgS. The lead rich films show an indirect gap and a direct optical gap whereas the mercury rich alloy films show only the direct optical gap. The optical gap increases linearly in polycrstalline films with increasing Hg concentration. The single crystal films, grown at 100 °C (0.07 ≦ x ≦ 0.50) have indirect and direct optical band gaps; the optical gap although increasing linearly with x has values smaller than the films grown at 25 °C.