With the recent strides in technology for flexible electronics, multi-nanolayer coatings are sputtered onto soft, plastic substrates resulting in optically transparent, conductive, flexible thin films. One limitation of expanding this technology resides in the fact that the attractive optical and electronic qualities are reduced as the number of layers or thickness of the layers are increased. The work presented here investigates the impact of increasingly thick films on flexible (PET) and rigid (silicon) substrates by utilizing complimentary characterization methods of x-ray and neutron reflectivity and grazing incidence x-ray scattering to study the depth profiles and structure of interfaces between consecutive layers. More specifically, the sputtering of layers of both tin doped indium oxide (ITO) and tungsten (W) with varying thickness are investigated. These results show that various compositional and/or density fluctuations exist that are dependent on sputtered material, layer thickness, and substrate flexibility. As an example, a sputtered W layer onto ITO on a silicon substrate increases the density of the supporting ITO layer at the substrate interface as the applied W or ITO layer increases thickness, while the same layer deposition on a PET substrate does not alter the density of the ITO supporting layer. However, ITO exhibits a decrease in oxygen content at the air interface. These density and compositional fluctuations, as well as the overall interfacial structure, throughout the depth profile of the thin film may have repercussions on the performance of the device.

Importance of substrate rigidity on the depth profile and interfacial structure of sputtered dielectric films

2019 Spring National Meeting

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