Photolysis and conductivity measurements at PbI2 surfaces

A. Friedenberg*, Y. Shapira

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Lead iodide is known to dissociate under band gap illumination. We investigated the decomposition products from sintered samples by quadrupole mass spectrometry and found that neutral atomic and molecular iodine species desorb from the illuminated surface. The desorption rate was measured as a function of light intensity and surface temperature. Atomic iodine desorption seems to be thermally activated throughout the temperature range (300-500 K), while molecular iodine has that feature only up to 400 K. We performed measurements of the dark and photoconductivity of PbI2 as functions of temperature and light intensity. Correlations of those results with the photolysis mass-spectrometric data indicate a possible model for the dissociation process. It suggests a diffusion-controlled mechanism of iodine desorption as well as of the dark conductivity, which seems to be ionic in that temperature range. The molecular iodine is apparently formed in surface sites, such as grain boundaries, which have a longer life-time for adsorbed iodine atoms as well as a dominant role in surface electronic conduction.

Original languageEnglish
Pages (from-to)606-622
Number of pages17
JournalSurface Science
Volume115
Issue number3
DOIs
StatePublished - 2 Mar 1982

Funding

FundersFunder number
Israel Academy of Science, Commission for Basic Research

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