A method to form anodic aluminum oxide dielectrics on separate gate patterns for the fabrication of ultra-flexible, low-voltage organic circuits

Abstract

Anodization of gate metals isan effective way to grow thin and robust metal oxide dielectrics to realizelow-voltage organic field-effect transistors (FETs). However, this technique hasbeen rarely applied to organic circuits because it is difficult to anodize anumber of isolated gate islands. In this study, we propose a method to form anodicaluminum oxide (AAO) dielectric on gate pattern islands in a single step forthe fabrication of ultra-flexible, low-voltage organic circuits. For this, a 2μm-thick Parylene substrate was formed on an aluminum (Al)-coated glasscarrier, and Al gate patterns were thermally deposited.Then, the gate islands were connected to a bottom Allayer through via-holes. After the anodizing process of the interconnected islands,the Parylene film was stripped from the Al-coated glass carrier for the electricalisolation of the gates. Likewise, the AAO dielectrics formed on the gate patternislands exhibited good electrical insulating properties and high capacitance values (190 nF·cm-2) with gooduniformity. By using the proposed AAO-on-island process, we successfully fabricated-3 V-operating p-type organic polymer FETs which have carrier mobilities of 0.2 cm2·V-1·s-1 and threshold voltages of -0.15 V.