Morphology dependent optical properties of inorganic–organic hybrid ZnO thin films

Interaction of the first few deposited atomic layers with the substrate plays an important role in the growth and morphology of very thin films of metals and semiconductors. Self-assembled monolayers (SAMs) of organic molecules have a wide range of applications, from molecular electronics to immobilization of biomolecules. SAMs of organic molecules can be used to control the morphology, electrical, magnetic, and optical properties of overgrown metals and semiconductors. Here we report the thickness-dependent variation in the morphology and the optical properties of ZnO deposited by RF sputtering on the SAM of 1-octadecanethiol (ODT) and 16-mercaptohexadecanoic acid (MHA) grown on Au/Si. Morphology of ZnO thin films deposited on the SAM strongly depended on the organic functional group of the SAM. Uniformly distributed clusters, like the formation of ZnO, were observed when deposited on ODT, whereas a uniform thin film of ZnO was grown when deposited on MHA SAM. Band gap of deposited thin films depends on the thickness and morphology of the deposited ZnO.