ToF-SIMS depth profiling of organic solar cell layers using an Ar cluster ion source

Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) is a very powerful technique for analyzing the outermost layers of organic and biological materials. The ion fluence in static SIMS is usually kept low enough to prevent decomposition of the organic/molecular species and as a result ToF-SIMS is able to detect and image high mass molecular species, such as polymer additives. Depth profiling, in contrast, uses a high ion fluence in order to remove material between each analysis cycle. Unfortunately, the high ion fluence results in not only erosion but also decomposition of the organic species. Recently, high mass Ar cluster ion sources have become available and are enabling depth profiling through organic layers. In this paper, the authors demonstrate that they can obtain and maintain molecular information throughout an organic solar cell test layer when erosion is performed using an Ar1500 + cluster ion source for material removal. Contrary they show that they cannot maintain molecular information when low energy monoatomic ion beams are used for material removal.