Advanced technique of vertical organic thin film transistor

The channel lengths of the top contact organic thin film transistors are usually defined during their fabrication by optical lithography or by shadow masking during the metal deposition process. Realizing short channel (sub-ten micron channel length) transistors by lithography will require costly lithography equipment. On the other hand, it is extremely challenging to achieve short channel transistors using the low cost shadow mask process. One low cost method of achieving short channel devices is to build vertical transistors with the transistor, where the channel gets defined in the vertical part of the device. This document shows that vertical channel top contact organic thin film transistor has been successfully realized on Si Substrate with SiO₂ as gate insulator and pentacene as the organic semiconductor. The active channel was defined on the vertical edge of a wide trench etched in the substrate. This helped in creating the device with channel lengths less than ten microns, much smaller than what could be typically achieved with the use of shadow masks. The sub-ten micron vertical organic thin film transistors were electrically characterized. The characteristics and transistor performance parameters estimated from these were compared with the transistor characteristics of the more standardized horizontal top contact organic thin film transistor of channel length (140μm).