Oxidative Chemical Vapor Deposition of Highly Conductive and Transparent Polymer Layers for Contact Fabrication in 2D-MoS₂-Based FET Structures

For 2D MoS₂ field-effect transistors (FETs), contact fabrication easily results in damaging the MoS₂ channel due to the fragility of the atomically thin structure, making it difficult to reliably achieve high-performance devices. To overcome this challenge, the deposition of highly conductive and transparent polymer layers from the gas phase (oxidative chemical vapor deposition (oCVD) [1]), is a promising approach that can lead to low-resistivity Ohmic contacts. In this work, we demonstrate a method for fabricating 2D MoS₂ bottom-gated FETs with poly (3, 4- ethylenedioxythiophene) (PEDOT) electrodes. PEDOT is a conductive polymer widely used as transparent electrode material. We used lithography to pattern oCVD-grown PEDOT layers and transferred them onto MoS₂ channels without aggressive chemical and physical treatments. This method allowed us to achieve a damage-free MoS₂ channel with a clean and smooth interface of the PEDOT electrodes, significantly decreasing the charged impurity and interface-roughness scattering processes. This universal approach could be applied to different 2D materials, thus enabling the fabrication low-resistivity Ohmic contacts in high-performance FETs without damaging the atomically thin crystals.<br/><br/>[1] Krieg, Meierhofer, Voss, et al., <i>Nature Communications</i> <b>11</b>, 5092 (2020).