Ion exchange in ultrathin films of cu₂s and zns under atomic layer deposition conditions

Diethyl zinc (DEZ), the standard metalorganic Zn²⁺ precursor used to synthesize ZnO by Atomic layer deposition (ALD), was shown to be used to convert an ultrathin Cu₂S film into ZnS and copper metal at low temperatures on a time scale of minutes. Cu₂S and ZnS films were synthesized by atomic layer deposition using standard A-B cycles at temperatures ranging from 135 to 150°C. The quartz crystal microbalance (QCM) measurements revealed large mass increases upon exposure of Cu₂S to DEZ and ZnS to Cu₂DBA. After exposure to DEZ, the Cu₂S absorbance spectrum lost the band-edge absorption at 1000 nm as well as the strong transition at approximately 600 nm. the conversion of ZnS to Cu ₂S via Cu₂DBA exposure demonstrated herein produces films with less islanding and requires less time than the traditional ALD route to Cu₂S.