The Organic Thin Film Transistor

An Organic Thin Film Transistor (OTFT) is a three-terminal device, in which a voltage applied to a gate electrode controls current flow between a source and drain electrode under an imposed bias. It is similar to the inorganic TFT (usually based on amorphous silicon substrate). The schematic is shown in Fig. 1.

Fig. 1

It is possible to realize Thin-Film Transistors using organic molecules (Organic-TFT, OTFT) with mobility exceeding 1 cm2/Vs (comparable to that of amorphous silicon transistors).

Our Research activity

Our research activity is focused on the characterization and modeling, the reliability study of OTFT, the influence of different technological parameters (active layer thickness, devices structure, processing conditions) on the performance and reliability of the devices. At this purpose we can perform accelerated electrical stress, illumination stress, UV exposure stress, thermal storage. We employ standard DC, AC, transient characterization (such as the Deep level transient spectroscopy, DLTS), and 2D simulation of devices characteristics to study the charge-trapping phenomena, the role of self-heating, the devices degradation.

Fig. 2 shows an example of the mobility degradation in a pentacene OTFT subjected to UV exposure. the OTFT transconductance is degraded under illumination: the higher the photon-energy, the faster is the degradation. Damage is stable even during vacuum storage

Fig. 2
SOURCE: N. Wrachien, et al., IEEE Transaction on Electron Devices, (59), p. 1501, 2012

MOST - Molecular and Organic Semiconductor Technology
Microelectronic Group - University of Padova