Channel Geometry Scaling Effect in Printed Inorganic Electrolyte-Gated Transistors

Unlike nanoscale silicon transistors, printed thin-film transistors usually rely on micrometer size channel lengths. The device dimensions, the morphology of the channel material, and the interface properties strongly influence important device parameters such as the threshold voltage ( V
_{\text th}
) and the transconductance parameter ( k). In this article, we analyze and model the dependence of critical electrical device properties of printed, electrolyte-gated transistors, based on crystalline indium oxide channel, for various device geometries. It is shown that the threshold voltage scales with the charge density at the electrolyte channel interface and is hence linearly dependent on the channel length ( L). Furthermore, nonlinear scaling effects in the transconductance parameter and in the ON-current are studied, which turn out to be dependent on both, channel width and length. Finally, we present a scaling model capturing the width/length dependencies of the studied transistor technology which enables the correct simulation of logic gates.