Origin of the modified electronic properties of Au formed on pentacene

A Au film formed on a pentacene layer, as a model system of a metal contact on a pentacene-based field-effect transistor, has been investigated. Unexpected pentacene derivatives and coarse morphology depending on the Au thickness are suggested as origins of the abnormal electronic structure of the Au film and the poor reproducibility of organic-based devices. The morphology of the Au film shows a strong dependency on the Au coverage. At 600 Å of Au, a lift of the pentacene layer is shown as a result of deformation of the cracked Au film induced by a relaxation of the intergranular stresses accumulated during the growth process.