Ge-Epitaxial-PbS Heterojunctions

Abstract

Films of lead sulfide have been grown on single‐crystal germanium substrates from a water solution of reacting chemicals. The details of the preparation method are described. Lauè back reflection and diffractometer measurements indicate that the films are single crystal with the same orientation as the substrate. Measurements were made of the photovoltage generated between the germanium and the lead sulfide as a function of wavelength between 1 and 4 μ at room temperature and at 77°K. At 77°K all samples showed a peak in photovoltage at 1.5 μ. In addition, samples grown on n‐type germanium show a response out to 3.3 μ. Finally, the time constant of the photovoltage was measured. At room temperature it was less than 10 μsec for all samples while at 77°K it was 25 μsec for the samples grown on n‐type germanium and less than 10 μsec for the remaining samples.