Impact of gold deposition parameters on the drain-source leakage current in top-contact pentacene-based thin-film transistors

Abstract

In this work the influence of gold deposition parameters such as substrate temperature and nominal contact thickness on the drain-source leakage current in top-contact pentacene-based thin-film transistors (TFTs) is investigated. The results reveal that the drain-source leakage current can be suppressed by increasing the substrate temperature and by decreasing the gold contact thickness. It is shown that the observed behavior cannot be fully explained by the standard leakage current model, which attributes the decrease of the leakage current to an increase of the contact resistance. Therefore an extended leakage current model is introduced which takes into account the so-called halo-effect, i.e. the formation of a layer of gold clusters during the gold diffusion process, yielding a parallel resistance between drain and source. It is shown that this model is able to describe both, the dependency of the leakage current on the substrate temperature as well as on the contact thickness.