CONTROL OF PEELING DURING CHEMICAL DEPOSITION OF THIN FILMS OF Bi2S3BY SURFACE PRETREATMENT WITH FUNCTIONALIZED SILANES

Clean glass surfaces have been treated with a series of compounds having the general formula, (CH3O)3Si(CH2)3X, where X is a selected functional group. Thin films of Bi2S3 were then deposited on the treated surfaces. The tendencies of the films to peel were observed as X was varied. The greatest resistance to peeling occurred when X was SH or (CH2)14CH3. Scanning electron microscopy showed that Bi2S3 films deposited on the surfaces having terminal SH groups had smaller particle size, were more homogeneous in appearance and possessed smaller intercrystalline voids than those deposited on untreated surfaces. The improvement of resistance to peeling after treatment with (CH3O)3Si(CH2)3SH is explained in terms of the formation of an initial glass-O-Si bond and the subsequent formation of a covalent Bi-S bond to the silane layer bound to the glass. Although the films prepared with X as (CH2)14CH3 did not peel readily, they were easily separated from the glass surface by mechanical means.