Dual beam organic depth profiling using large argon cluster ion beams

Argon cluster sputtering of an organic multilayer reference material consisting of two organic components, 4,4′‐bis[N‐(1‐naphthyl‐1‐)‐N‐phenyl‐ amino]‐biphenyl (NPB) and aluminium tris‐(8‐hydroxyquinolate) (Alq 3 ), materials commonly used in organic light‐emitting diodes industry, was carried out using time‐of‐flight SIMS in dual beam mode. The sample used in this study consists of a ~400‐nm‐thick NPB matrix with 3‐nm marker layers of Alq 3 at depth of ~50, 100, 200 and 300 nm. Argon cluster sputtering provides a constant sputter yield throughout the depth profiles, and the sputter yield volumes and depth resolution are presented for Ar‐cluster sizes of 630, 820, 1000, 1250 and 1660 atoms at a kinetic energy of 2.5 keV. The effect of cluster size in this material and over this range is shown to be negligible.