Nano Gate Dielectrics for Low Voltage Operation of Organic Thin Film Transistors

Abstract

Two types of nanometer thick gate dielectrics were employed in order to implement a low voltage operation for organic thin film transistors (OTFT). The first device used an organic monolayer that was formed through a self-assembly process of (benzyloxy)-alkyltrichlorosilane (BTS) on a SiO2 substrate. The BTS-OTFTs produced a threshold voltage of -0.50±0.11 V, a mobility of 0.12±0.05 cm2 V-1 s-1, and a on/off current ratio of (1.87±1.22)×102. The second type of gate dielectric used self-grown Al2O3, which was directly grown on a pre-existing Al gate electrode by oxygen plasma process. The self-grown Al2O3-OTFTs exhibited a mobility of 0.12±0.015 cm2 V-1 s1, a threshold voltage of -1.18±0.027 V, and an on/off current ratio of (8.76±5.3)×103. In particular, as the Al2O3 layer is directly grown on a pre-existing Al gate electrode, an additional patterning process for the gate dielectric is not necessary; thus, the fabrication process is simplified. Furthermore, the process is a low temperature, dry process, thereby allowing for low cost fabrications and flexible applications.