Patterned growth of CdS by combined Electrochemical Atomic Layer Epitaxy and Microcontact printing techniques

Ultrathin films of well-ordered CdS on Ag(1 1 1) can be attained by electrochemical atomic layer epitaxy (ECALE) technique, which is based on self-limiting reactions, such as underpotential deposition. The layer-by-layer electrodeposition on single crystal faces allows a precise control of film thickness and yields semiconducting nanostructures of high crystallinity. In this paper, the ECALE method has been used to deposit CdS on Ag(1 1 1) covered by patterns of hexadecanethiol, C16SH. The patterned Ag(1 1 1) was obtained by using the microcontact printing technique of a polydimethylsiloxane (PDMS) stamp previously immersed in C16SH. The stamp used in this work produced thiol strips 320 nm large, with an 850 nm pitch. The deposition of CdS takes only place on the uncovered silver substrate whereas it is prevented on the thiols monolayers, yielding CdS patterned according to the used stamp. The deposit has been characterized by electrochemical techniques and AFM measurements.