The structure of vapour-deposited arsenic sulphides

Abstract High resolution X-ray and neutron correlation functions have been obtained for arsenic sulphide bulk glass and vapour-deposited films by making measurements to high momentum transfers. These data are compared with a vatiety of models and it is concluded that the structure of the films is dominated by the presence of As 4 S 4 molecules in the vapour phase, which results in more As-As bonds than the minimum required by stoichoimetry. The extent to which these As 4 S 4 molecules polymerise in the as-deposited film is unclear, but depends strongly on preparation conditions.