Organic multi-layer transistor constructed by molecular self-assembly of pyryl phosphonic acid

We present a simple method to construct a multi-layer transistor by exploiting self-assembly of pyryl phosphonic acid (PYPA) molecules between a set of interdigitated metal electrodes on a silicon dioxide surface. The self-assembly method used for the construction of the device makes it compatible for integration with Complementary Metal Oxide Semiconductor (CMOS) circuits. Using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), we have established that PYPA molecules form either a dense 0.9 nm thin monolayer or a polycrystalline multilayer on SiO₂ surface with the specific step height of 2.5 nm. By studying the gating effect of the transistors, we measured the carrier mobility in PYPA as a function of the applied electric field. Using these results, we have proposed a conduction model in the PYPA self-assembled device.