The pseudobinary alloy ${\mathrm{Pb}}_{1-x}{\mathrm{Sr}}_x\mathrm{S}$ exists as a single phase at all compositions. With change in composition the optical absorption edge at 300 K changes continuously from 0.4 eV for PbS to 4.6 eV for SrS. For compositions with $x\le 0.2$, $p$-type and $n$-type thin films have been prepared by doping with Tl or Ag and with Bi, respectively. Similar single-phase behavior and composition dependence of the energy gap are found with ${\mathrm{Pb}}_{1-x}{\mathrm{Ca}}_x\mathrm{S}$.

• Received 12 July 1982

DOI:https://doi.org/10.1103/PhysRevB.26.5617