Organic Depth Profiling by Cluster Ion Sputter

Depth profiling of model organic thin films composed of Alq3 and α-NPD on ITO-covered glass has been performed by Ar+ or C60++ ion sputter. In the case of conventional 2keV-Ar+ ion sputter, as a result of the severe damage there are no peaks characteristic of their molecular structure, and a specific elemental ion of Al+ is the only sign of Alq3. Al+ profiles of Alq3 with different thickness show a constant sputtering yield. On the other hand, we can observe the survival of C18H12N2O2Al+ (Alq2+) by use of 20 keV-C60++ cluster ion sputter. However, Alq3 films show the quite dose-dependent sputtering yields. The dose dependency is caused by the accumulation of the sample damage, which is represented by the increase of C+ and C2+. The intensities of low mass fragment ions can be available as an index of the accumulating sample damage.