We made nanometer-scale (gate length of 30 nm) organic thin-film transistors using a self-assembled monolayer (2 nm thick) as a gate insulator. The fabrication steps combine electron-beam lithography and lift-off techniques for the deposition of both metal electrodes and organic semiconductors with a chemical approach (self-assembly of organic molecules) to fabricate the gate insulator. Good performances of these transistors (with a record subthreshold slop of 350 mV/decade and a cutoff frequency of 20 kHz) and low-voltage operation (<2 V) are demonstrated down to a gate length of 200 nm. A gate voltage modulation of the source-to-drain tunnel current is demonstrated for the 30 nm gate length device.

It is demonstrated that monolayers of organic molecules (long chain hydrocarbons) as thin as 1.9 nm, deposited by the self-assembly technique on silicon, form high performance electrically insulating barriers. Their properties are compared with those of silicon dioxide. Leakage current densities through the organic monolayers of the order of 10−8–10−7A/cm2 have been obtained. These values are 4–5 decades lower than those for silicon dioxide of equivalent thickness. Larger tunneling barriers for organic monolayers than for silicon dioxide explain these results.

We demonstrate the realization and functioning of a hybrid (organic/silicon) nanometer-size field effect transistor (nano-FET) having a gate length of 25 nm. The gate insulator is an organic self-assembled monolayer (SAM) of alkyltrichlorosilanes (∼2 nm thick). We have used densely packed SAMs with functionalized end groups (–CH3, –CH=CH2, –COOH) that all exhibit reduced leakage current density (10−8–10−5 A/cm2). This nano-FET is free of punchthrough down to 50 nm, and shows a good field effect behavior at 25 nm. This demonstrates the compatibility of these SAMs with semiconductor device processes and their wide capability for applications in nanometer-scale electronics.