TEMPLATE-ASSISTED ELECTROCHEMICAL DEPOSITION OF ULTRATHIN FILMS OF CADMIUM-SULFIDE

Uniform thin films of cadmium sulfide were prepared by template-assist ed electrochemical deposition on gold electrodes covered with Langmuir -Blodgett (LB) films. An electrolytic cell was used for the production of low concentrations of S- to effect heterogeneous crystallization o n LB films, while preventing homogeneous precipitation, 3-, 4- and 5-l ayer LB films of cadmium arachidate were investigated. Characterizatio n of deposited films by optical microscopy, atomic force microscopy an d energy dispersive X-ray analysis of film composition indicated that a variety of different types of CdS films can be produced depending on the type of LB film used, the electrode at which template-assisted de position is carried out, the magnitude and frequency of alternating po tentials used, and the deposition time used. In general, hydrophilic o rganic films that present cadmium carboxylate groups to the deposition surface (i.e. 3- and 5-layer LB films) supported crystallization of C dS, while those that present hydrophobic, methyl groups (i.e. 4-layer LB films and self-assembled monolayers of alkanethiolates on gold) did not. The best methods for the rapid deposition of conformal, ultrathi n films (< 100 nm) of CdS used highly-ordered 5-layer LB films at grou nded electrodes. The data presented suggest that templating with LB fi lms, when used together with electrochemical deposition, has potential for the convenient production of oriented crystalline thin films of c admium sulfide and similar materials. (C) 1997 Elsevier Science S.A.