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

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 SiO(2) substrate. The BTS-OTFTs produced a threshold voltage of -0.50 +/- 0.11 V, a mobility of 0.12 +/- 0.05 cm(2) V(-1) s(-1), and a on/off current ratio of (1.87 +/- 1.22) x 10(2). The second type of gate dielectric used self-grown Al(2)O(3), which was directly grown on a pre-existing Al gate electrode by oxygen plasma process. The self-grown Al(2)O(3)-OTFTs exhibited a mobility of 0.12 +/- 0.015 cm(2) V(-1) s(1), a threshold voltage of -1.18 +/- 0.027 V, and an on/off current ratio of (8.76 +/- 5.3) x 10(3). In particular, as the Al(2)O(3) 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.