Plasma interaction with Zn nano layer on organic materials for analysis of early stage of inorganic/organic hybrid multi-layer formation

Interactions between Ar-O₂ mixture plasmas and Zn thin film on Tris(8-hydroxyquinolinato) aluminium (Alq₃) were investigated on the basis of nondestructive depth analyses of chemical bonding states at the Zn/Alq₃ interface via hard x-ray photoelectron spectroscopy (HXPES). The HXPES Zn 2p_3/2 spectrum measured at take-off angle (TOA)=20° clearly shows significant increase of the Zn-O bond after Ar-O₂ mixture plasma exposure. This result indicated that the Ar-O₂ mixture plasma exposure has made it possible to form ZnO thin films on organic materials due to oxidation of Zn thin film. The HXPES C 1s spectra measurement at TOA=80° and 42° indicated that the Ar-O₂ mixture plasma exposure does not give significant damage to the chemical bonding states in regions up to about 20nm from the Zn/Alq₃ interface. Whereas, the results of HXPES measurement at a TOA=20° suggested that the oxygen radicals through the Zn thin film cause oxidation of Alq₃ at shallower region up to about a few nm from the interface.